Ni^(2+)and Cd^(2+)in wastewater accumulated through the ecological chain and could jeopardize human health.Adsorption of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite was an important way to solve the prob...Ni^(2+)and Cd^(2+)in wastewater accumulated through the ecological chain and could jeopardize human health.Adsorption of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite was an important way to solve the problem of resource utilization of solid waste from agar production.Our previous study confirmed that recovered perlite from agar extraction residue had better pore size and specific surface area than commercial perlite.However,the adsorption efficiency and adsorption mechanism of recovered perlite were the main factors limiting its adsorption application.The adsorption process of Ni^(2+)and Cd^(2+)by recovered perlite in aqueous solution was described by the pseudo-second-order kinetic equation,and the relevant adsorption mechanism was mainly chemisorption.Compared with commercial perlite,the adsorption removal rate of Ni^(2+)and Cd^(2+)by enzymatic recovered perlite could reach 92.9%and 89.2%,respectively,and were improved by 12.63%and 13.03%.Langmuir isothermal adsorption model could better describe the isothermal adsorption process of recovered perlite on heavy metal Ni^(2+)and Cd^(2+),and the relevant adsorption mechanism was mainly monolayer adsorption.The X-ray photoelectron spectroscopy(XPS)results indicated that the decrease of Si—O Si^(2+)hydroxyl coordination bond and the increase of C—Si bond might make the binding effect of recovered perlite with heavy metals stronger.The competitive adsorption of Ni^(2+)and Cd^(2+)by recovered perlite was still dominated by chemisorption and monolayer adsorption.This study was expected to provide a theoretical basis and technical support for the removal of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite from seaweed residue.展开更多
The purpose of this study was to identify and compare the degradation efficiencies of free and entrapped bacterial consortia(Staphylococcus capitis CP053957.1 and Achromobacter marplatensis MT078618.1)to different pol...The purpose of this study was to identify and compare the degradation efficiencies of free and entrapped bacterial consortia(Staphylococcus capitis CP053957.1 and Achromobacter marplatensis MT078618.1)to different polymers such as Sodium Alginate(SA),Sodium Alginate/Poly(Vinyl Alcohol)(SA/PVA),and Bushnell Haas Agar(BHA).In addition to SA and SA/PVA,which are cost-effective,non-toxic and have different functional groups,BHA,which is frequently encountered in laboratory-scale studies but has not been used as an entrapment material until now.Based on these,the polymers with different surface morphologies and chemical compositions were analyzed by SEM and FT-IR.While the petroleum removal efficiency was higher with the entrapped bacterial consortia than with the free one,BHA-entrapped bacterial consortium enhanced the petroleum removal more than SA and SA/PVA.Accordingly,the degradation rate of bacterial consortia entrapped with BHA was 2.039 day^(-1),SA/PVA was 1.560,SA was 0.993,the half-life period of BHA-entrapped bacterial consortia is quite low(t_(1/2)=0.339)compared with SA(t_(1/2)=0.444)and SA/PVA(t_(1/2)=0.697).The effects of the four main factors such as:amount of BHA(0.5,1,1.5,2,2.5,3 g),disc size(4,5,6,7,8 mm),inoculum concentration(1,2.5,5,7.5,10 mL),and incubation period on petroleum removal were also investigated.The maximum petroleum removal(94.5%)was obtained at≥2.5 mL of bacterial consortium entrapped in 2 g BHA with a 7 mm disc size at 168 h and the results were also confirmed by statistical analysis.Although a decrease was observed during the reuse of bacterial consortium entrapped in BHA,the petroleum removal was still above 50%at 10th cycle.Based on GC-MS analysis,the removal capacity of BHA-entrapped consortium was over 90%for short-chain n-alkanes and 80%for medium-chain n-alkanes.Overall,the obtained data are expected to provide a potential guideline in cleaning up the large-scale oil pollution in the future.Since there has been no similar study investigating petroleum removal with the bacterial consortia entrapped with BHA,this novel entrapment material can potentially be used in the treatment of petroleum pollution in advanced remediation studies.展开更多
Three materials(agar,konjac glucomannan(KGM)andκ-carrageenan)were used to prepare ternary systems,i.e.,sol-gels and their dried composites conditioned at varied relative humidity(RH)(33%,54%and 75%).Combined methods,...Three materials(agar,konjac glucomannan(KGM)andκ-carrageenan)were used to prepare ternary systems,i.e.,sol-gels and their dried composites conditioned at varied relative humidity(RH)(33%,54%and 75%).Combined methods,e.g.,scanning electron microscopy,small-angle X-ray scattering,infrared spectroscopy(IR)and X-ray diffraction(XRD),were used to disclose howκ-carrageenan addition tailors the features of agar/KGM/κ-carrageenan ternary system.As affirmed by IR and XRD,the ternary systems withκ-carrageenan below 25%(agar/KGM/carrageenan,50:25:25,m/m)displayed proper component interactions,which increased the sol-gel transition temperature and the hardness of obtained gels.For instance,the ternary composites could show hardness about 3 to 4 times higher than that for binary counterpart.These gels were dehydrated to acquire ternary composites.Compared to agar/KGM composite,the ternary composites showed fewer crystallites and nanoscale orders,and newly-formed nanoscale structures from chain assembly.Such multi-scale structures,for composites withκ-carrageenan below 25%,showed weaker changes with RH,as revealed by especially morphologic and crystalline features.Consequently,the ternary composites with lessκ-carrageenan(below 25%)exhibited stabilized elongation at break and hydrophilicity at different RHs.This hints to us that agar/KGM/κ-carrageenan composite systems can display series applications with improved features,e.g.,increased sol-gel transition point.展开更多
The sulfate groups in agar structure played a good role in the formation of fiber.However,commercially available agar is usually extracted from red algae by alkali treatment to decrease the content of sulfate group fo...The sulfate groups in agar structure played a good role in the formation of fiber.However,commercially available agar is usually extracted from red algae by alkali treatment to decrease the content of sulfate group for the purpose of high gel strength.In this paper,an alkali-free method of agar extraction from Gracilaria lemaneiformis was proposed for the wet-spinning purpose.This method is environmentally friendly,reduces the extraction steps,saves energy,and reduces the production cost of agar fiber.The improved agar preparation process not only has higher agar yield,but also has higher molecular weight and sulfate group content,which is beneficial to the preparation and forming of fiber and makes the fiber have higher mechanical strength and elongation.Therefore,this extraction technology has broad application prospect in the textile field.展开更多
Background: Colonization with methicillin-resistant Staphylococcus aureus(MRSA) poses a hygiene risk that does not spare field hospitals or military medical field camps during military deployments. Diagnostic options ...Background: Colonization with methicillin-resistant Staphylococcus aureus(MRSA) poses a hygiene risk that does not spare field hospitals or military medical field camps during military deployments. Diagnostic options for unambiguously identifying MRSA isolates are usually scarce in military environments. In this study, we assessed the stepwise application of two different selective agars for the specific identification of MRSA in screening analyses.Methods: Nasal swabs from 1,541 volunteers were subjected to thioglycollate broth enrichment and subsequently screened on CHROMagar MRSA selective agar for the identification of MRSA. The MRSA identity of suspiciouslooking colonies was confirmed afterwards or excluded by another selective agar, chrom ID MRSA. All isolates from the selective agars with MRSA-specific colony morphology were identified by biochemical methods and mass spectrometry.Results: The initial CHROMagar MRSA screening identified suspicious colonies in 36 out of 1541 samples. A total of 25 of these 36 isolates showed MRSA-like growth on chrom ID agar. Out of these 25 isolates, 24 were confirmed as MRSA, while one isolate was identified as Staphylococcus kloosii. From the 11 strains that did not show suspicious growth on chrom ID agar, 3 were methicillin-sensitive Staphylococcus aureus(MSSA, with one instance of cocolonization with Corynebacterium spp.), 2 were confirmed as MRSA(with 1 instance of co-colonization with MSSA), 2 were lost during passaging and could not be re-cultured, one could not be identified by the applied approaches, and the remaining 3 strains were identified as Staphylococcus saprophyticus, Staphylococcus hominis(co-colonized with Macrococcus caseolyticus) and Staphylococcus cohnii, respectively.Conclusion: The application of the selective agar CHROMagar MRSA alone proved to be too non-specific to allow for a reliable diagnosis of the presence of MRSA. The combined use of two selective agars in a stepwise approach reduced this non-specificity with an acceptably low loss of sensitivity. Accordingly, such a stepwise screening approach might be an option for resource-restricted military medical field camps.展开更多
Agar,agarose,and agaropectin were extracted from the red alga Ahnfeltia plicata,and their properties and structures were characterized.Agar was extracted by a comparatively low alkaline consumption of 1.2%.It exhibite...Agar,agarose,and agaropectin were extracted from the red alga Ahnfeltia plicata,and their properties and structures were characterized.Agar was extracted by a comparatively low alkaline consumption of 1.2%.It exhibited a gel strength of 1 152.50±74.25 g/cm^2 and a sulfate content of 0.55%±0.08%.The yield of agar from A.plicata was 24.53%,which is higher than those of other agarophytes commonly used in China.Three kinds of the method were compared for the purification of agarose,and the physicochemical properties of agarose that was prepared under the optimal condition were identical to those of commercially available agarose.Furthermore,agaropectin was purified from A.plicata and characterized by GC,HPLC,UV-spectrum,and FI-IR to understand its composition and structure.It was the first time to comprehensively study the agar and its fractions from the red alga of A.plicata.This research provided an eco-friendly agar extraction method from A.plicata and revealed its potential application for the production of agar,agarose,and agaropectin.展开更多
Depolymerization of agar was performed using agarase, which was extracted from the cell-free medium of a culture of marine bacterial Alterornonas sp. nov. SY 37-12. After ethanol fractionation and lyophilization, the ...Depolymerization of agar was performed using agarase, which was extracted from the cell-free medium of a culture of marine bacterial Alterornonas sp. nov. SY 37-12. After ethanol fractionation and lyophilization, the water-soluble agar polysaccharide (WSAP3) was collected. The anti-tumor activity of the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 reached 48.7% at a dose of 64mg kg^-1 after 15 days treatment. WSAP3 enhanced the aetivities of superoxide dismutase and catalase, which suggests that WSAP3 was effective in promoting the antioxidation ability and eliminating danger from free radicals. The result of flow cytometry showed that the WSAP3 had no activities of cell cycle inhibition or apoptosis-inducing activities. The anti-oxidation of WSAP3 was further confirmed by test in vitro, which might play an important role in anti-tumor activity. The immunological regulation of WSAP3, especially its effect on the phagocytosis ratio and phagocytosis index of rophage was also assayed in test in vivo.展开更多
Gelidium amansii agar was fractionated on DEAE-cellulose and four fractions were obtained sequentially. The yields of 1.0 mol/L NaCl fraction and 2.5 mol/L NaCl fraction were 2.80% and 2.03%. They are highly sulfated ...Gelidium amansii agar was fractionated on DEAE-cellulose and four fractions were obtained sequentially. The yields of 1.0 mol/L NaCl fraction and 2.5 mol/L NaCl fraction were 2.80% and 2.03%. They are highly sulfated agar, and named as agaropectin with sulfate content being 22.8% and 32.5%, respectively. The anticoagulant experiment results show that agaropectin could effectively prolong the coagulation time in a dose-dependent manner in vitro. Agaropection could be absorbed and effectively prolong the plasma coagulation time in vivo. After intragastric administration at the doses of 100, 200, and 400 mg/kg·d in rats for 15 days, TT (thrombin time), CT (coagulation time), PT (prothrombin time), and APTT (activated partial thromboplastin time) could be effectively prolonged and the plasma Fib level could be significantly lowered.展开更多
[Objective] This study aimed to compare the detection results of antibodies against infectious bursal disease virus with test strips and agar gel immunodiffusion method. [Method] Antibodies against infectious bursal d...[Objective] This study aimed to compare the detection results of antibodies against infectious bursal disease virus with test strips and agar gel immunodiffusion method. [Method] Antibodies against infectious bursal disease virus in chicken serum were detected using test strips developed in our laboratory, and the results were comparad^with that using traditional agar diffusion method. [Result] The comparative study of the two methods showed that the sensitivity of test strips was eight times over agar gel immunodiffusion; test strips showed higher detection rate in the deter- mination test of 216 clinical samples, with high specificity, easy preservation, and simple and rapid operation, thereby being more suitable for the monitoring of clinical antibodies. [Conclusion] Test strips could replace the existing serological methods, having great promotion and application value in antibody monitoring.展开更多
Gracilaria tenuistipitata varliui Zhang el Xia is cultivated at two different salinities (21, 33) in the laboratory for 4 weeks. The daily growth rate is determined. The total agar yield and fractional agar compositio...Gracilaria tenuistipitata varliui Zhang el Xia is cultivated at two different salinities (21, 33) in the laboratory for 4 weeks. The daily growth rate is determined. The total agar yield and fractional agar composition are analyzed. Results show that algae grow faster in low salinity. The total agar yield is higher under high salinity conditions than under low salinity conditions. Among the eight fractions extracted, the yields of cold water extract and 40% ethanol extract are about the highest In low salinities the yields of autoclaved extract and 60% ethanol extract are higher, while the yield of cold water extract is lower relative to high salinities.展开更多
The red seaweed Melanothamnus somalensis was investigated as potential economic source of agar. The effect of different conditions of alkali pre-treatment on chemical properties of agar was evaluated. Agar was extract...The red seaweed Melanothamnus somalensis was investigated as potential economic source of agar. The effect of different conditions of alkali pre-treatment on chemical properties of agar was evaluated. Agar was extracted by various concentrations of NaOH (4%, 6% and 8%) and heated at different temperatures (70 ℃, 75 ℃ and 80 ℃) for different durations (2 h, 2.75 h and 3.5 h). The yields-molecular weight (Mw) and sulfate contents of extracted agar were analysed and characterized by FTIR spectroscopy. The yield was significantly increased at these treatments from 23.29% to 30.86%. Mw studied by HPLC ranged from (.12.45 ± 0.21) × 10^5 to (8.60 ± 2.40) × 10^5 Da. FTIR bands show sulfate groups in C4 and C6 ofgalactose and no sulfate group were found on both C2 of galactose and C2 of 3,6-anhydrogalactose. All treatments showed a high sulfate content that ranged from 5.4% to 10.1%. These properties were found to be significantly affected by the alkali pre-treatment concentration (p 〈 0.05). In conclusion, agar extracted in this study was considered acceptable for industrial application and the optimal conditions for extraction were found to be at 6% NaOH at 70 ℃ for 2 hours.展开更多
Establishment of an in vitro system that allows the development of testicular germ cells to sperm will be valuable for studies of spermatogenesis and future treatments for male infertility. In the present study, we de...Establishment of an in vitro system that allows the development of testicular germ cells to sperm will be valuable for studies of spermatogenesis and future treatments for male infertility. In the present study, we developed in vitro culture conditions using three-dimensional agar culture system (SACS), which has the capacity to induce testicular germ cells to reach the final stages of spermatogenesis, including spermatozoa generation. Seminiferous tubules from testes of 7-day-old mice were enzymatically dissociated, and intratubular cells were cultured in the upper layer of the SACS in RPMI medium supplemented with fetal calf serum (FCS). The lower layer of the SACS contained only RPMI medium supplemented with FCS. Colonies in the upper layer were isolated after 14 and 28 days of culture and were classified according to their size. Immunofluorescence and real-time PCR were used to analyse specific markers expressed in undifferentiated and differentiated spermatogonia (Vasa, Dazl, OCT-4, C-Kit, GFR- a-l, CD9 and a-6-integrin), meiotic cells (LDH, Crem-1 and Boule) and post-meiotic cells (Protamine-1, Acrosin and SP-IO). Our results reveal that it is possible to induce mouse testicular pre-meiotic germ cell expansion and induce their differentiation to spermatozoa in SACS. The spermatozoa showed normal morphology and contained acrosomes. Thus, our results demonstrate that SACS could be used as a novel in vitro system for the maturation of pre-meiotic mouse germ cells to post-meiotic stages and morphologically-normal spermatozoa.展开更多
Objective:To investigate and optimize microbial media that substitute peptone agar using brebra seed defatted flour.Methods:Defatted process.inoculums preparation,evaluation of bacterial growth,preparation of cooked a...Objective:To investigate and optimize microbial media that substitute peptone agar using brebra seed defatted flour.Methods:Defatted process.inoculums preparation,evaluation of bacterial growth,preparation of cooked and hydrolyzed media and growth turbidity of tested bacteria were determined.Results:Two percent defatted flour was found to be suitable concentration for the growth of pathogenic bacteria:Escherichia coli(ATCC 25922)(E,coli),Pseudomonas aeruginosa(ATCC27853),Salmonella(NCTC 8385)and Shigella flexneri(ATCC 12022)(S.flexneri),while 3%defatted flour was suitable for Staphylococcus aureus(ATCC 25923)(S.aureus).E.coli(93±1)and S.flexneri(524±1)colony count were significantly(P≤0.05)greater in defatted flour without supplement than in supplemented medium.E.coli[(3.72×10~9±2)CFU/mL],S.aureus[(7.4×10~9±2)CFU/mL],S.flexneri[(4.03×10~9±2)CFU/mL]and Salmonella[(2.37×10~9±1)CFU/mL]in non-hydrolyzed sample were statistically(P≤0.05)greater than hydrolyzed one and commercial peptone agar.Colony count of Salmonella[(4.55≤10~9±3)CFU/mL],S.flexneri[(5.40≤10~9±3)CFU/mL]and Lyesria moncytogenes(ATCC 19116)[(5.4×10~9±3)CFU/mL]on raw defatted flour agar was significantly(P≤0.05)greater than cooked defatted flour and commercial peptone agar.Biomass of E.coli,S.aureus.Salmonella and Enterococcus faecalis in non-hydrolyzed defatted flour is highly increased over hydrolyzed defatted flour and commercial peptone broth.Conclusions:The defatted flour agar was found to be better microbial media or comparable with peptone agar.The substances in it can serve as sources of carbon,nitrogen,vitamins and minerals that are essential to support the growth of microorganisms without any supplements.Currently,all supplements of peptone agar are very expensive in the market.展开更多
Gracilaria tenuistipitata var Liui were mono cultivated and co cultivated with Pinctada martensii under high (33) and low (21) salinity conditions in laboratory. The daily growth rate of the alga was determined. Tissu...Gracilaria tenuistipitata var Liui were mono cultivated and co cultivated with Pinctada martensii under high (33) and low (21) salinity conditions in laboratory. The daily growth rate of the alga was determined. Tissue carbon and nitrogen contents, the yield and fractional composition of agar were analyzed. Results showed that: 1. Gracilaria grew better under low salinity conditions, the daily growth rate was twice that under high salinity conditions. Co cultivated algae grew faster than mono cultivated algae under low salinity conditions, the daily growth rate was about 37.6% higher. 2. Compared with mono cultivated algae, tissue nitrogen contents of co cultivated algae were higher, while the C:N ratios were much lower. 3. The agar yields of co cultivated algae were much lower than those of mono cultivated algae. Agar yield was found to be negatively correlated to the tissue nitrogen contents, and positively correlated to the C:N ratios. 4. The highest fractional yields obtained from co cultivated algae were extracted with 40% ethanol, while from mono cultivated algae, the highest fractional yields obtained were extracted with distilled water at room temperature.展开更多
Growth of?Paecilomyces hepiali?in various agar media and yield of fruit bodies in rice based media were?studied. The best growth in agar media was obtained at 25℃?(61.86 mm colony diameter in 14 days). The initial ag...Growth of?Paecilomyces hepiali?in various agar media and yield of fruit bodies in rice based media were?studied. The best growth in agar media was obtained at 25℃?(61.86 mm colony diameter in 14 days). The initial agar media pH range?from?6 to 8 was found to be?the?most favourable for mycelial growth. This study found that agars made with powders of cereal grains alone do not support good mycelial growth of?P. hepiali. Addition of peptone improved mycelial growth significantly. The most favourable carbon sources were Mannose, Fructose and Glucose. Organic nitrogen sources were found to be?the?most preferred. The results demonstrated that brown rice is better than polished rice in yield of fruit bodies. Addition of peptone was found to be quite significant in enhancing yield of fruit bodies. Peptone, as a supplement, gave a better yield than addition of egg yolk, albumen and a mixture of the two. The medium with?40 g brown rice, 0.325 g glucose, 0.65 g sucrose, 2 g peptone and 65 ml corn steep liquor was found to be?the?most favourable and it yielded 19.3 g of fresh fruit bodies.展开更多
The phosphate mineral struvite is basically formed in urinary tracks and kidney. One of the analogous compounds of struvite is potassium magnesium phosphate hexahydrate (KMgPO4·6H2O), known as struvite-k crys...The phosphate mineral struvite is basically formed in urinary tracks and kidney. One of the analogous compounds of struvite is potassium magnesium phosphate hexahydrate (KMgPO4·6H2O), known as struvite-k crystal and found in animal urinary calculi. In the present investigation, struvite-k crystals were grown by single diffusion and double diffusion techniques in agar gelmedium. The grown crystals were analyzed by optical microscopy, scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDXA) and thermogravimetric analysis (TGA). Optical microscopy and SEM exhibited the different morphologies. The FTIR spectra revealed the presence of water molecules, stretching and bending vibrations of phosphate (PO4) ions. However the powder XRD results from the crystalline nature. Elemental composition in the crystal was obtained by EDXA, while 36.89% weight loss of water molecules is observed in TGA study.展开更多
Salmonellosis is the most prevalent bacterial foodborne disease in many countries worldwide. Utilization of probiotics is one of the most accepted ways to reduce<span style="font-family:;" "="&q...Salmonellosis is the most prevalent bacterial foodborne disease in many countries worldwide. Utilization of probiotics is one of the most accepted ways to reduce<span style="font-family:;" "=""> </span><i><span style="font-family:Verdana;">Salmonella</span></i><span style="font-family:Verdana;">, especially lactic acid bacteria, as it has proven to reduce the enteric</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">pathogens in monogastric and ruminant livestock animals through different mechanisms such as antimicrobials production, competitive adhesion to the gastrointestinal tract, and immune stimulation. Prebiotics could be utilized solely for health benefits as an alternative to probiotics or in addition to probiotics for a synergistic effect known as synbiotics. The aim of this study was to compare effects of different probiotic strains (</span><i><span style="font-family:Verdana;">Lactobacillus acidophilus </span></i><span style="font-family:Verdana;">(La-14)</span><span><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Lactobacillus paracasei </span></i></span><span style="font-family:Verdana;">(Lpc-37)</span><span><span style="font-family:Verdana;">,</span><i> <span style="font-family:Verdana;">Streptococcus thermophiles </span></i></span><span></span><span style="font-family:Verdana;">(St-21)</span><span><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Bifidobacterium bifidum </span></i></span><span style="font-family:Verdana;">(Bb-06), and </span><i><span style="font-family:Verdana;">Aspergillus niger </span></i><span style="font-family:Verdana;">(ATCC<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">®</span>16888</span></span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;">)</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> and without prebiotics (Mannose;Xylose;Galactooligosaccharides GOS;Inulin;and Dandelion extract) on lowering </span><i><span style="font-family:Verdana;">Salmonella heidelberg</span></i><span style="font-family:Verdana;"> CFU </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;">. Different inhibition levels probiotic strains were assessed and compared in the presence and absence of 2.5% prebiotic compounds using cross-streaking and agar well diffusion assays. Recommendations for the growth of selected microorganisms such as temperature and oxygen conditions were taken into consideration. All the analysis was conducted in triplicates.</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">The results showed that all the probiotics strains except</span><span style="font-family:;" "=""> </span><i><span style="font-family:Verdana;">S. thermophiles </span></i><span style="font-family:;" "=""><span style="font-family:Verdana;">were able to significantly (</span><i><span style="font-family:Verdana;">P </span></i><span style="font-family:Verdana;">< 0.05) inhibit the growth of </span><i><span style="font-family:Verdana;">S. heidelberg </span></i><span style="font-family:Verdana;">in at least one of the assays. The difference in</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">inhibition percentage confirms that probiotic strains have multiple inhibition mechanisms, such as production of antimicrobials, lower pH by producing organic acids (acetic acid, lactic acid, etc.), and inhibition of pathogen</span><span style="font-family:Verdana;">’</span><span style="font-family:Verdana;">s virulence factor expression, and production of lipopolysaccharide solubilizing compounds.</span>展开更多
One in 58 strains of bacteria isolated from the compost showed clear colonies after a few days of growth on the plates containing medium made of only agar and water.Water suspension contained only agar (2 and 8g·...One in 58 strains of bacteria isolated from the compost showed clear colonies after a few days of growth on the plates containing medium made of only agar and water.Water suspension contained only agar (2 and 8g·L -1 ) with two controls (normal saline,LB medium) was inoculated with the bacterium BR5-1 to see whether there was an increasement of the alive bacteria concentration after 48 h of the growth.The results showed that there was a significant rising of the alive bacteria concentration in the agar susp...展开更多
Members of the Pseudomonas family are commonly found in nature, some species are pathogenic for humans, as well as being resistant to multiple disinfectants. Various studies have revealed that benzalkonium chloride (B...Members of the Pseudomonas family are commonly found in nature, some species are pathogenic for humans, as well as being resistant to multiple disinfectants. Various studies have revealed that benzalkonium chloride (BKC) has an inhibitory effect on many bacteria but it has no significant effect on Pseudomonas aeruginosa. Cetrimide agar medium is recommended for the isolation and enumeration of Ps. aeruginosa in food and environmental samples. However, there are claims that for some food factories and in particular the bottled water industry, the selectivity of this medium is not sufficient. The aim of the current research is the creation of a more selective medium for Ps. aeruginosa with BKC. A total of 28 isolates were isolated with Cetrimide agar from raw water samples and identified using biochemical tests and commercial identification kits. All the bacteria were inoculated in Cetrimide agar plates containing 0 - 625 μg/mL BKC. The Petri dishes were incubated at 37°C and 42°C for 24 h. The results showed that 375 μg/mL BKC was sufficient to suppress Burk. pseudomallei at both incubation temperatures. Ps. fluorescens-35 could not grow at 42°C at any concentration, including the control, and was suppressed at 500 μg/mL BKC. All the Ps. aeruginosa isolates and control strain were grown at both incubation temperatures at 375 μg/mL BKC concentration. In conclusion, the analysis of Ps. aeruginosa showed that the growth of accompanying flora may be suppressed by adding 375-μg/mL BKC into Cetrimide agar and incubating at an elevated temperature of 42°C.展开更多
基金financially supported by National Natural Science Foundation of China(22038012,32172339,and 22178142)National Key Research and Development Program(2023YF D2100603)。
文摘Ni^(2+)and Cd^(2+)in wastewater accumulated through the ecological chain and could jeopardize human health.Adsorption of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite was an important way to solve the problem of resource utilization of solid waste from agar production.Our previous study confirmed that recovered perlite from agar extraction residue had better pore size and specific surface area than commercial perlite.However,the adsorption efficiency and adsorption mechanism of recovered perlite were the main factors limiting its adsorption application.The adsorption process of Ni^(2+)and Cd^(2+)by recovered perlite in aqueous solution was described by the pseudo-second-order kinetic equation,and the relevant adsorption mechanism was mainly chemisorption.Compared with commercial perlite,the adsorption removal rate of Ni^(2+)and Cd^(2+)by enzymatic recovered perlite could reach 92.9%and 89.2%,respectively,and were improved by 12.63%and 13.03%.Langmuir isothermal adsorption model could better describe the isothermal adsorption process of recovered perlite on heavy metal Ni^(2+)and Cd^(2+),and the relevant adsorption mechanism was mainly monolayer adsorption.The X-ray photoelectron spectroscopy(XPS)results indicated that the decrease of Si—O Si^(2+)hydroxyl coordination bond and the increase of C—Si bond might make the binding effect of recovered perlite with heavy metals stronger.The competitive adsorption of Ni^(2+)and Cd^(2+)by recovered perlite was still dominated by chemisorption and monolayer adsorption.This study was expected to provide a theoretical basis and technical support for the removal of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite from seaweed residue.
文摘The purpose of this study was to identify and compare the degradation efficiencies of free and entrapped bacterial consortia(Staphylococcus capitis CP053957.1 and Achromobacter marplatensis MT078618.1)to different polymers such as Sodium Alginate(SA),Sodium Alginate/Poly(Vinyl Alcohol)(SA/PVA),and Bushnell Haas Agar(BHA).In addition to SA and SA/PVA,which are cost-effective,non-toxic and have different functional groups,BHA,which is frequently encountered in laboratory-scale studies but has not been used as an entrapment material until now.Based on these,the polymers with different surface morphologies and chemical compositions were analyzed by SEM and FT-IR.While the petroleum removal efficiency was higher with the entrapped bacterial consortia than with the free one,BHA-entrapped bacterial consortium enhanced the petroleum removal more than SA and SA/PVA.Accordingly,the degradation rate of bacterial consortia entrapped with BHA was 2.039 day^(-1),SA/PVA was 1.560,SA was 0.993,the half-life period of BHA-entrapped bacterial consortia is quite low(t_(1/2)=0.339)compared with SA(t_(1/2)=0.444)and SA/PVA(t_(1/2)=0.697).The effects of the four main factors such as:amount of BHA(0.5,1,1.5,2,2.5,3 g),disc size(4,5,6,7,8 mm),inoculum concentration(1,2.5,5,7.5,10 mL),and incubation period on petroleum removal were also investigated.The maximum petroleum removal(94.5%)was obtained at≥2.5 mL of bacterial consortium entrapped in 2 g BHA with a 7 mm disc size at 168 h and the results were also confirmed by statistical analysis.Although a decrease was observed during the reuse of bacterial consortium entrapped in BHA,the petroleum removal was still above 50%at 10th cycle.Based on GC-MS analysis,the removal capacity of BHA-entrapped consortium was over 90%for short-chain n-alkanes and 80%for medium-chain n-alkanes.Overall,the obtained data are expected to provide a potential guideline in cleaning up the large-scale oil pollution in the future.Since there has been no similar study investigating petroleum removal with the bacterial consortia entrapped with BHA,this novel entrapment material can potentially be used in the treatment of petroleum pollution in advanced remediation studies.
基金the National Natural Science Foundation of China(32172240)BL19U2 beamline of National Facility for Protein Science in Shanghai(NFPS)at Shanghai Synchrotron Radiation Facility,for their assistance during data collection。
文摘Three materials(agar,konjac glucomannan(KGM)andκ-carrageenan)were used to prepare ternary systems,i.e.,sol-gels and their dried composites conditioned at varied relative humidity(RH)(33%,54%and 75%).Combined methods,e.g.,scanning electron microscopy,small-angle X-ray scattering,infrared spectroscopy(IR)and X-ray diffraction(XRD),were used to disclose howκ-carrageenan addition tailors the features of agar/KGM/κ-carrageenan ternary system.As affirmed by IR and XRD,the ternary systems withκ-carrageenan below 25%(agar/KGM/carrageenan,50:25:25,m/m)displayed proper component interactions,which increased the sol-gel transition temperature and the hardness of obtained gels.For instance,the ternary composites could show hardness about 3 to 4 times higher than that for binary counterpart.These gels were dehydrated to acquire ternary composites.Compared to agar/KGM composite,the ternary composites showed fewer crystallites and nanoscale orders,and newly-formed nanoscale structures from chain assembly.Such multi-scale structures,for composites withκ-carrageenan below 25%,showed weaker changes with RH,as revealed by especially morphologic and crystalline features.Consequently,the ternary composites with lessκ-carrageenan(below 25%)exhibited stabilized elongation at break and hydrophilicity at different RHs.This hints to us that agar/KGM/κ-carrageenan composite systems can display series applications with improved features,e.g.,increased sol-gel transition point.
基金supported by the Program of National Natural Science Foundation of China(52173037)Natural Science Foundation of Shandong Province(ZR2020ME061)+2 种基金Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(IRT14R30)State Key Laboratory of Bio-Fibers and Eco-Textiles of Qingdao University(ZFT201810,ZKT17)Yunnan Expert Workstation Project(202105AF150061).
文摘The sulfate groups in agar structure played a good role in the formation of fiber.However,commercially available agar is usually extracted from red algae by alkali treatment to decrease the content of sulfate group for the purpose of high gel strength.In this paper,an alkali-free method of agar extraction from Gracilaria lemaneiformis was proposed for the wet-spinning purpose.This method is environmentally friendly,reduces the extraction steps,saves energy,and reduces the production cost of agar fiber.The improved agar preparation process not only has higher agar yield,but also has higher molecular weight and sulfate group content,which is beneficial to the preparation and forming of fiber and makes the fiber have higher mechanical strength and elongation.Therefore,this extraction technology has broad application prospect in the textile field.
文摘Background: Colonization with methicillin-resistant Staphylococcus aureus(MRSA) poses a hygiene risk that does not spare field hospitals or military medical field camps during military deployments. Diagnostic options for unambiguously identifying MRSA isolates are usually scarce in military environments. In this study, we assessed the stepwise application of two different selective agars for the specific identification of MRSA in screening analyses.Methods: Nasal swabs from 1,541 volunteers were subjected to thioglycollate broth enrichment and subsequently screened on CHROMagar MRSA selective agar for the identification of MRSA. The MRSA identity of suspiciouslooking colonies was confirmed afterwards or excluded by another selective agar, chrom ID MRSA. All isolates from the selective agars with MRSA-specific colony morphology were identified by biochemical methods and mass spectrometry.Results: The initial CHROMagar MRSA screening identified suspicious colonies in 36 out of 1541 samples. A total of 25 of these 36 isolates showed MRSA-like growth on chrom ID agar. Out of these 25 isolates, 24 were confirmed as MRSA, while one isolate was identified as Staphylococcus kloosii. From the 11 strains that did not show suspicious growth on chrom ID agar, 3 were methicillin-sensitive Staphylococcus aureus(MSSA, with one instance of cocolonization with Corynebacterium spp.), 2 were confirmed as MRSA(with 1 instance of co-colonization with MSSA), 2 were lost during passaging and could not be re-cultured, one could not be identified by the applied approaches, and the remaining 3 strains were identified as Staphylococcus saprophyticus, Staphylococcus hominis(co-colonized with Macrococcus caseolyticus) and Staphylococcus cohnii, respectively.Conclusion: The application of the selective agar CHROMagar MRSA alone proved to be too non-specific to allow for a reliable diagnosis of the presence of MRSA. The combined use of two selective agars in a stepwise approach reduced this non-specificity with an acceptably low loss of sensitivity. Accordingly, such a stepwise screening approach might be an option for resource-restricted military medical field camps.
基金Supported by the Public Science and Technology Research Funds Projects of Ocean(No.201405040)the Key Research and Development Program in Shandong Province(No.2016GSF121034)the Jiangsu Provincial Key R&D Project(No.BE2015335)
文摘Agar,agarose,and agaropectin were extracted from the red alga Ahnfeltia plicata,and their properties and structures were characterized.Agar was extracted by a comparatively low alkaline consumption of 1.2%.It exhibited a gel strength of 1 152.50±74.25 g/cm^2 and a sulfate content of 0.55%±0.08%.The yield of agar from A.plicata was 24.53%,which is higher than those of other agarophytes commonly used in China.Three kinds of the method were compared for the purification of agarose,and the physicochemical properties of agarose that was prepared under the optimal condition were identical to those of commercially available agarose.Furthermore,agaropectin was purified from A.plicata and characterized by GC,HPLC,UV-spectrum,and FI-IR to understand its composition and structure.It was the first time to comprehensively study the agar and its fractions from the red alga of A.plicata.This research provided an eco-friendly agar extraction method from A.plicata and revealed its potential application for the production of agar,agarose,and agaropectin.
文摘Depolymerization of agar was performed using agarase, which was extracted from the cell-free medium of a culture of marine bacterial Alterornonas sp. nov. SY 37-12. After ethanol fractionation and lyophilization, the water-soluble agar polysaccharide (WSAP3) was collected. The anti-tumor activity of the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 reached 48.7% at a dose of 64mg kg^-1 after 15 days treatment. WSAP3 enhanced the aetivities of superoxide dismutase and catalase, which suggests that WSAP3 was effective in promoting the antioxidation ability and eliminating danger from free radicals. The result of flow cytometry showed that the WSAP3 had no activities of cell cycle inhibition or apoptosis-inducing activities. The anti-oxidation of WSAP3 was further confirmed by test in vitro, which might play an important role in anti-tumor activity. The immunological regulation of WSAP3, especially its effect on the phagocytosis ratio and phagocytosis index of rophage was also assayed in test in vivo.
基金the Innovative Key Project of Chinese Academy of Sciences (KZCX2-YW-209)the Department of Science and Technology of Shandong Province (2007BS07004)
文摘Gelidium amansii agar was fractionated on DEAE-cellulose and four fractions were obtained sequentially. The yields of 1.0 mol/L NaCl fraction and 2.5 mol/L NaCl fraction were 2.80% and 2.03%. They are highly sulfated agar, and named as agaropectin with sulfate content being 22.8% and 32.5%, respectively. The anticoagulant experiment results show that agaropectin could effectively prolong the coagulation time in a dose-dependent manner in vitro. Agaropection could be absorbed and effectively prolong the plasma coagulation time in vivo. After intragastric administration at the doses of 100, 200, and 400 mg/kg·d in rats for 15 days, TT (thrombin time), CT (coagulation time), PT (prothrombin time), and APTT (activated partial thromboplastin time) could be effectively prolonged and the plasma Fib level could be significantly lowered.
文摘[Objective] This study aimed to compare the detection results of antibodies against infectious bursal disease virus with test strips and agar gel immunodiffusion method. [Method] Antibodies against infectious bursal disease virus in chicken serum were detected using test strips developed in our laboratory, and the results were comparad^with that using traditional agar diffusion method. [Result] The comparative study of the two methods showed that the sensitivity of test strips was eight times over agar gel immunodiffusion; test strips showed higher detection rate in the deter- mination test of 216 clinical samples, with high specificity, easy preservation, and simple and rapid operation, thereby being more suitable for the monitoring of clinical antibodies. [Conclusion] Test strips could replace the existing serological methods, having great promotion and application value in antibody monitoring.
文摘Gracilaria tenuistipitata varliui Zhang el Xia is cultivated at two different salinities (21, 33) in the laboratory for 4 weeks. The daily growth rate is determined. The total agar yield and fractional agar composition are analyzed. Results show that algae grow faster in low salinity. The total agar yield is higher under high salinity conditions than under low salinity conditions. Among the eight fractions extracted, the yields of cold water extract and 40% ethanol extract are about the highest In low salinities the yields of autoclaved extract and 60% ethanol extract are higher, while the yield of cold water extract is lower relative to high salinities.
文摘The red seaweed Melanothamnus somalensis was investigated as potential economic source of agar. The effect of different conditions of alkali pre-treatment on chemical properties of agar was evaluated. Agar was extracted by various concentrations of NaOH (4%, 6% and 8%) and heated at different temperatures (70 ℃, 75 ℃ and 80 ℃) for different durations (2 h, 2.75 h and 3.5 h). The yields-molecular weight (Mw) and sulfate contents of extracted agar were analysed and characterized by FTIR spectroscopy. The yield was significantly increased at these treatments from 23.29% to 30.86%. Mw studied by HPLC ranged from (.12.45 ± 0.21) × 10^5 to (8.60 ± 2.40) × 10^5 Da. FTIR bands show sulfate groups in C4 and C6 ofgalactose and no sulfate group were found on both C2 of galactose and C2 of 3,6-anhydrogalactose. All treatments showed a high sulfate content that ranged from 5.4% to 10.1%. These properties were found to be significantly affected by the alkali pre-treatment concentration (p 〈 0.05). In conclusion, agar extracted in this study was considered acceptable for industrial application and the optimal conditions for extraction were found to be at 6% NaOH at 70 ℃ for 2 hours.
文摘Establishment of an in vitro system that allows the development of testicular germ cells to sperm will be valuable for studies of spermatogenesis and future treatments for male infertility. In the present study, we developed in vitro culture conditions using three-dimensional agar culture system (SACS), which has the capacity to induce testicular germ cells to reach the final stages of spermatogenesis, including spermatozoa generation. Seminiferous tubules from testes of 7-day-old mice were enzymatically dissociated, and intratubular cells were cultured in the upper layer of the SACS in RPMI medium supplemented with fetal calf serum (FCS). The lower layer of the SACS contained only RPMI medium supplemented with FCS. Colonies in the upper layer were isolated after 14 and 28 days of culture and were classified according to their size. Immunofluorescence and real-time PCR were used to analyse specific markers expressed in undifferentiated and differentiated spermatogonia (Vasa, Dazl, OCT-4, C-Kit, GFR- a-l, CD9 and a-6-integrin), meiotic cells (LDH, Crem-1 and Boule) and post-meiotic cells (Protamine-1, Acrosin and SP-IO). Our results reveal that it is possible to induce mouse testicular pre-meiotic germ cell expansion and induce their differentiation to spermatozoa in SACS. The spermatozoa showed normal morphology and contained acrosomes. Thus, our results demonstrate that SACS could be used as a novel in vitro system for the maturation of pre-meiotic mouse germ cells to post-meiotic stages and morphologically-normal spermatozoa.
基金supported by the University of Gondar:General Director.Research & Community Service Core Process,Grant NO:UOG/Budget/no.6215
文摘Objective:To investigate and optimize microbial media that substitute peptone agar using brebra seed defatted flour.Methods:Defatted process.inoculums preparation,evaluation of bacterial growth,preparation of cooked and hydrolyzed media and growth turbidity of tested bacteria were determined.Results:Two percent defatted flour was found to be suitable concentration for the growth of pathogenic bacteria:Escherichia coli(ATCC 25922)(E,coli),Pseudomonas aeruginosa(ATCC27853),Salmonella(NCTC 8385)and Shigella flexneri(ATCC 12022)(S.flexneri),while 3%defatted flour was suitable for Staphylococcus aureus(ATCC 25923)(S.aureus).E.coli(93±1)and S.flexneri(524±1)colony count were significantly(P≤0.05)greater in defatted flour without supplement than in supplemented medium.E.coli[(3.72×10~9±2)CFU/mL],S.aureus[(7.4×10~9±2)CFU/mL],S.flexneri[(4.03×10~9±2)CFU/mL]and Salmonella[(2.37×10~9±1)CFU/mL]in non-hydrolyzed sample were statistically(P≤0.05)greater than hydrolyzed one and commercial peptone agar.Colony count of Salmonella[(4.55≤10~9±3)CFU/mL],S.flexneri[(5.40≤10~9±3)CFU/mL]and Lyesria moncytogenes(ATCC 19116)[(5.4×10~9±3)CFU/mL]on raw defatted flour agar was significantly(P≤0.05)greater than cooked defatted flour and commercial peptone agar.Biomass of E.coli,S.aureus.Salmonella and Enterococcus faecalis in non-hydrolyzed defatted flour is highly increased over hydrolyzed defatted flour and commercial peptone broth.Conclusions:The defatted flour agar was found to be better microbial media or comparable with peptone agar.The substances in it can serve as sources of carbon,nitrogen,vitamins and minerals that are essential to support the growth of microorganisms without any supplements.Currently,all supplements of peptone agar are very expensive in the market.
文摘Gracilaria tenuistipitata var Liui were mono cultivated and co cultivated with Pinctada martensii under high (33) and low (21) salinity conditions in laboratory. The daily growth rate of the alga was determined. Tissue carbon and nitrogen contents, the yield and fractional composition of agar were analyzed. Results showed that: 1. Gracilaria grew better under low salinity conditions, the daily growth rate was twice that under high salinity conditions. Co cultivated algae grew faster than mono cultivated algae under low salinity conditions, the daily growth rate was about 37.6% higher. 2. Compared with mono cultivated algae, tissue nitrogen contents of co cultivated algae were higher, while the C:N ratios were much lower. 3. The agar yields of co cultivated algae were much lower than those of mono cultivated algae. Agar yield was found to be negatively correlated to the tissue nitrogen contents, and positively correlated to the C:N ratios. 4. The highest fractional yields obtained from co cultivated algae were extracted with 40% ethanol, while from mono cultivated algae, the highest fractional yields obtained were extracted with distilled water at room temperature.
文摘Growth of?Paecilomyces hepiali?in various agar media and yield of fruit bodies in rice based media were?studied. The best growth in agar media was obtained at 25℃?(61.86 mm colony diameter in 14 days). The initial agar media pH range?from?6 to 8 was found to be?the?most favourable for mycelial growth. This study found that agars made with powders of cereal grains alone do not support good mycelial growth of?P. hepiali. Addition of peptone improved mycelial growth significantly. The most favourable carbon sources were Mannose, Fructose and Glucose. Organic nitrogen sources were found to be?the?most preferred. The results demonstrated that brown rice is better than polished rice in yield of fruit bodies. Addition of peptone was found to be quite significant in enhancing yield of fruit bodies. Peptone, as a supplement, gave a better yield than addition of egg yolk, albumen and a mixture of the two. The medium with?40 g brown rice, 0.325 g glucose, 0.65 g sucrose, 2 g peptone and 65 ml corn steep liquor was found to be?the?most favourable and it yielded 19.3 g of fresh fruit bodies.
文摘The phosphate mineral struvite is basically formed in urinary tracks and kidney. One of the analogous compounds of struvite is potassium magnesium phosphate hexahydrate (KMgPO4·6H2O), known as struvite-k crystal and found in animal urinary calculi. In the present investigation, struvite-k crystals were grown by single diffusion and double diffusion techniques in agar gelmedium. The grown crystals were analyzed by optical microscopy, scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDXA) and thermogravimetric analysis (TGA). Optical microscopy and SEM exhibited the different morphologies. The FTIR spectra revealed the presence of water molecules, stretching and bending vibrations of phosphate (PO4) ions. However the powder XRD results from the crystalline nature. Elemental composition in the crystal was obtained by EDXA, while 36.89% weight loss of water molecules is observed in TGA study.
文摘Salmonellosis is the most prevalent bacterial foodborne disease in many countries worldwide. Utilization of probiotics is one of the most accepted ways to reduce<span style="font-family:;" "=""> </span><i><span style="font-family:Verdana;">Salmonella</span></i><span style="font-family:Verdana;">, especially lactic acid bacteria, as it has proven to reduce the enteric</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">pathogens in monogastric and ruminant livestock animals through different mechanisms such as antimicrobials production, competitive adhesion to the gastrointestinal tract, and immune stimulation. Prebiotics could be utilized solely for health benefits as an alternative to probiotics or in addition to probiotics for a synergistic effect known as synbiotics. The aim of this study was to compare effects of different probiotic strains (</span><i><span style="font-family:Verdana;">Lactobacillus acidophilus </span></i><span style="font-family:Verdana;">(La-14)</span><span><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Lactobacillus paracasei </span></i></span><span style="font-family:Verdana;">(Lpc-37)</span><span><span style="font-family:Verdana;">,</span><i> <span style="font-family:Verdana;">Streptococcus thermophiles </span></i></span><span></span><span style="font-family:Verdana;">(St-21)</span><span><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Bifidobacterium bifidum </span></i></span><span style="font-family:Verdana;">(Bb-06), and </span><i><span style="font-family:Verdana;">Aspergillus niger </span></i><span style="font-family:Verdana;">(ATCC<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">®</span>16888</span></span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;">)</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> and without prebiotics (Mannose;Xylose;Galactooligosaccharides GOS;Inulin;and Dandelion extract) on lowering </span><i><span style="font-family:Verdana;">Salmonella heidelberg</span></i><span style="font-family:Verdana;"> CFU </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;">. Different inhibition levels probiotic strains were assessed and compared in the presence and absence of 2.5% prebiotic compounds using cross-streaking and agar well diffusion assays. Recommendations for the growth of selected microorganisms such as temperature and oxygen conditions were taken into consideration. All the analysis was conducted in triplicates.</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">The results showed that all the probiotics strains except</span><span style="font-family:;" "=""> </span><i><span style="font-family:Verdana;">S. thermophiles </span></i><span style="font-family:;" "=""><span style="font-family:Verdana;">were able to significantly (</span><i><span style="font-family:Verdana;">P </span></i><span style="font-family:Verdana;">< 0.05) inhibit the growth of </span><i><span style="font-family:Verdana;">S. heidelberg </span></i><span style="font-family:Verdana;">in at least one of the assays. The difference in</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">inhibition percentage confirms that probiotic strains have multiple inhibition mechanisms, such as production of antimicrobials, lower pH by producing organic acids (acetic acid, lactic acid, etc.), and inhibition of pathogen</span><span style="font-family:Verdana;">’</span><span style="font-family:Verdana;">s virulence factor expression, and production of lipopolysaccharide solubilizing compounds.</span>
基金Supported by National High-tech Research and Development Program of China (863 Program) (20060110Z4023)
文摘One in 58 strains of bacteria isolated from the compost showed clear colonies after a few days of growth on the plates containing medium made of only agar and water.Water suspension contained only agar (2 and 8g·L -1 ) with two controls (normal saline,LB medium) was inoculated with the bacterium BR5-1 to see whether there was an increasement of the alive bacteria concentration after 48 h of the growth.The results showed that there was a significant rising of the alive bacteria concentration in the agar susp...
文摘Members of the Pseudomonas family are commonly found in nature, some species are pathogenic for humans, as well as being resistant to multiple disinfectants. Various studies have revealed that benzalkonium chloride (BKC) has an inhibitory effect on many bacteria but it has no significant effect on Pseudomonas aeruginosa. Cetrimide agar medium is recommended for the isolation and enumeration of Ps. aeruginosa in food and environmental samples. However, there are claims that for some food factories and in particular the bottled water industry, the selectivity of this medium is not sufficient. The aim of the current research is the creation of a more selective medium for Ps. aeruginosa with BKC. A total of 28 isolates were isolated with Cetrimide agar from raw water samples and identified using biochemical tests and commercial identification kits. All the bacteria were inoculated in Cetrimide agar plates containing 0 - 625 μg/mL BKC. The Petri dishes were incubated at 37°C and 42°C for 24 h. The results showed that 375 μg/mL BKC was sufficient to suppress Burk. pseudomallei at both incubation temperatures. Ps. fluorescens-35 could not grow at 42°C at any concentration, including the control, and was suppressed at 500 μg/mL BKC. All the Ps. aeruginosa isolates and control strain were grown at both incubation temperatures at 375 μg/mL BKC concentration. In conclusion, the analysis of Ps. aeruginosa showed that the growth of accompanying flora may be suppressed by adding 375-μg/mL BKC into Cetrimide agar and incubating at an elevated temperature of 42°C.