Insight into the spoilage heterogeneity of meat-borne bacteria isolates with high-producing collagenase

Chilled chicken is inevitably contaminated by microorganisms during slaughtering and processing,resulting in spoilage.Cutting parts of chilled chicken,especially wings,feet,and other skin-on products,are abundant in collagen,which may be the primary target for degradation by spoilage microorganisms.In this work,a total of 17 isolates of spoilage bacteria that could secrete both collagenase and lipase were determined by raw-chicken juice agar(RJA)method,and the results showed that 7 strains of Serratia,Aeromonas,and Pseudomonas could significantly decompose the collagen ingredients.The gelatin zymography showed that Serratia liquefaciens(F5)and(G7)had apparent degradation bands around 50 kDa,and Aeromonas veronii(G8)and Aeromonas salmonicida(H8)had a band around.65 and 95 kDa,respectively.The lipase and collagenase activities were detected isolate-by-isolate,with F5 showing the highest collagenase activity.For spoilage ability on meat in situ,F5 performed strongest in spoilage ability,indicated by the total viable counts,total volatile basic nitrogen content,sensory scores,lipase,and collagenase activity.This study provides a theoretical basis for spoilage heterogeneity of strains with high-producing collagenase in meat.

Modern approaches for detection of volatile organic compounds in metabolic studies focusing on pathogenic bacteria:Current state of the art

Pathogenic microorganisms produce numerous metabolites,including volatile organic compounds(VOCs).Monitoring these metabolites in biological matrices(e.g.,urine,blood,or breath)can reveal the presence of specific microorganisms,enabling the early diagnosis of infections and the timely implementation of tar-geted therapy.However,complex matrices only contain trace levels of VOCs,and their constituent com-ponents can hinder determination of these compounds.Therefore,modern analytical techniques enabling the non-invasive identification and precise quantification of microbial VOCs are needed.In this paper,we discuss bacterial VOC analysis under in vitro conditions,in animal models and disease diagnosis in humans,including techniques for offline and online analysis in clinical settings.We also consider the advantages and limitations of novel microextraction techniques used to prepare biological samples for VOC analysis,in addition to reviewing current clinical studies on bacterial volatilomes that address inter-species in-teractions,the kinetics of VOC metabolism,and species-and drug-resistance specificity.

Antiseptic Efficacy of A Soap Made from Biosurfactants Isolated from Bacillus and Lactobacillus against Pathogenic Bacteria

The aim of our study was to use a biosurfactant produced by Bacillus and Lactobacillus isolates as an antiseptic in the formulation of local soap. A total of 60 isolates were characterized by microbiological techniques (30 Bacillus and 30 Lactobacillus) and the ability to produce biosurfactants was demonstrated by a hydrocarbon emulsification index (E24). The emulsification indexes (E24) varied from 9% to 100% for Bacillus and from 33% to 100% for Lactobacillus as well. The antagonistic assay showed that biosurfactants were able to inhibit the formation of biofilms and growth of pathogens such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Salmonella typhirium, Shigella boydii and Proteus mirabilis. The biosurfactant consortium (BioC) from Bacillus consortium and from Lactobacillus was able to inhibit biofilm formation and the pathogens growth. The BioC was stable to alkaline pH and the temperatures stability of Biosurfactant was ranging from 50°C to 90°C. The soap was made by the cold saponification process using one biosurfactant consortium formulated. This soap has a pH of 10 and showed good cleaning power and good foam stability. Similarly, the soap showed good antiseptic power and disinfection power against all pathogens tested. Handwashing is critical to preventing disease transmission. The persistence of pathogens in waste water was evaluated. The BioS produced showed good disinfection power against all pathogens tested. The valor of reduction on the hands and in the waste water was significantly more than compared to the control soaps used. This soap could be used in the prevention, fighting, and treatment of bacterial and viral infections.

Nature’s Pharmacy under Siege: Investigating Antibiotic Resistance Pattern in Endophytic Bacteria of Medicinal Plants

Antibiotic resistance poses a significant global health threat, necessitating a thorough understanding of its prevalence in various ecological contexts. Medicinal plants, renowned for their therapeutic properties, host endophytic bacteria that produce bioactive compounds. Understanding antibiotic resistance dynamics in these bacteria is vital for human health and antibiotic efficacy preservation. In this study, we investigated antibiotic resistance profiles in endophytic bacteria from five medicinal plants: Thankuni, Neem, Aparajita, Joba, and Snake plant. We isolated and characterized 113 endophytic bacteria, with varying resistance patterns observed against multiple antibiotics. Notably, 53 strains were multidrug-resistant (MDR), with 14 exhibiting extensive drug resistance (XDR). Thankuni-associated bacteria displayed 44% MDR and 11% XDR, while Neem-associated bacteria showed higher resistance (60% MDR, 13% XDR). Aparajita-associated bacteria had lower resistance (22% MDR, 6% XDR), whereas Joba-associated bacteria exhibited substantial resistance (54% MDR, 14% XDR). Snake plant-associated bacteria showed 7% MDR and 4% XDR. Genus-specific distribution revealed Bacillus (47%), Staphylococcus (21%), and Klebsiella (11%) as major contributors to MDR. Our findings highlight diverse drug resistance patterns among plant-associated bacteria and underscore the complexity of antibiotic resistance dynamics in diverse plant environments. Identification of XDR strains emphasizes the severity of the antibiotic resistance problem, warranting further investigation into contributing factors.

Distribution of pathogenic bacteria and antimicrobial sensitivity of eye infections in Suzhou

AIM:To investigate the types of bacteria in patients with eye infections in Suzhou and their drug resistance to commonly used antibacterial drugs.METHODS:The clinical data of 155 patients were retrospectively collected in this study,and the pathogenic bacteria species and drug resistance of each pathogenic bacteria were analyzed.RESULTS:Among the 155 patients(age from 12 to 87 years old,with an average age of 57,99 males and 56 females)with eye infections(160 eyes:74 in the left eye,76 in the right eye and 5 in both eyes,all of which were exogenous),71(45.81%)strains were gram-positive bacteria,23(14.84%)strains were gram-negative bacteria and 61(39.35%)strains were fungi.Gram-positive bacteria were highly resistant to penicillin and erythromycin(78.87%and 46.48%respectively),but least resistant to vancomycin at 0.Gram-negative bacteria were highly resistant to cefoxitin and compound sulfamethoxazole(100%and 95.65%respectively),but least resistant to meropenem at 0.Comparison of the resistance of gram-positive and gram-negative bacteria to some drugs revealed statistically significant differences(P<0.05)in the resistance of both to cefoxitin,cotrimoxazole,levofloxacin,cefuroxime,ceftriaxone and ceftazidime,and both had higher rates of resistance to gram-negative bacteria than to gram-positive bacteria.The distribution of bacterial infection strains showed that Staphylococcus epidermidis was the most common strain in the conjunctiva,cornea,aqueous humor or vitreous body and other eye parts.Besides,Fusarium and Pseudomonas aeruginosa were also among the most common strains of conjunctival and corneal infections.CONCLUSION:Gram-positive bacteria are the dominant bacteria in eye infections,followed by gram-negative bacteria and fungi.Considering the resistance of gramnegative bacteria to multiple drugs,monitoring of bacteria should be strengthened in eye bacterial infections for effective prevention and control to reduce complications caused by eye infections.

The Impact of Nitrogen-Fixing Bacteria, Iron, and Zinc Foliar Application on Dry Land Yellow Mustard (Brassica juncea) Grain and Oil Production

The study, conducted at the Research Farm of the College of Agriculture, University of Tabriz in 2021, focused on the effects of various nitrogen-fixing bacterial isolates, biofertilizers containing nitrogen and phosphorus, as well as iron and zinc foliar applications on mustard growth under rainfed conditions. The results indicated that biofertilizers, whether used alone or in combination with chemical fertilizers, produced comparable grain and oil outputs compared to chemical fertilizers alone. Additionally, the application of iron and zinc through foliar spraying significantly enhanced both grain and oil production. These findings suggest that integrating nitrogen-fixing bacteria and biofertilizers could reduce reliance on chemical nitrogenous fertilizers, leading to decreased production expenses, improved product quality, and minimized environmental impact. This study highlights the potential for sustainable agricultural practices in dry land farming as a viable alternative to traditional chemical-intensive methods. Substituting chemical nitrogenous fertilizers with nitrogen-fixing bacteria or biofertilizers could result in cost savings in mustard grain and oil production while promoting environmental sustainability.

Application of Next Generation Sequencing for Rapid Identification of Lactic Acid Bacteria

The rapid identification of lactic acid bacteria,which are essential microorganisms in the food industry,is of great significance for industrial applications.The identification of lactic acid bacteria traditionally relies on the isolation and identification of pure colonies.While this method is well-established and widely used,it is not without limitations.The subjective judgment inherent in the isolation and purification process introduces potential for error,and the incomplete nature of the isolation process can result in the loss of valuable information.The advent of next generation sequencing has provided a novel approach to the rapid identification of lactic acid bacteria.This technology offers several advantages,including rapidity,accuracy,high throughput,and low cost.Next generation sequencing represents a significant advancement in the field of DNA sequencing.Its ability to rapidly and accurately identify lactic acid bacteria strains in samples with insufficient information or in the presence of multiple lactic acid bacteria sets it apart as a valuable tool.The application of this technology not only circumvents the potential errors inherent in the traditional method but also provides a robust foundation for the expeditious identification of lactic acid bacteria strains and the authentication of bacterial powder in industrial applications.This paper commences with an overview of traditional and molecular biology methods for the identification of lactic acid bacteria.While each method has its own advantages,they are not without limitations in practical application.Subsequently,the paper provides an introduction of the principle,process,advantages,and disadvantages of next generation sequencing,and also details its application in strain identification and rapid identification of lactic acid bacteria.The objective of this study is to provide a comprehensive and reliable basis for the rapid identification of industrial lactic acid bacteria strains and the authenticity identification of bacterial powder.

Allergen degradation of bee pollen by lactic acid bacteria fermentation and its alleviatory effects on allergic reactions in BALB/c mice

Food allergy as a global health problem threatens food industry.Bee pollen(BP)is a typical food with allergenic potentials,although it performs various nutritional/pharmacological functions to humans.In this study,lactic acid bacteria(LAB)were used to ferment Brassica napus BP for alleviating its allergenicity.Four novel allergens(glutaredoxin,oleosin-B2,catalase and lipase)were identified with significant decreases in LAB-fermented BP(FBP)than natural BP by proteomics.Meanwhile,metabolomics analysis showed significant increases of 28 characteristic oligopeptides and amino acids in FBP versus BP,indicating the degradation of LAB on allergens.Moreover,FBP showed alleviatory effects in BALB/c mice,which relieved pathological symptoms and lowered production of allergic mediators.Microbial high-throughput sequencing analysis showed that FBP could regulate gut microbiota and metabolism to strengthen immunity,which were closely correlated with the alleviation of allergic reactivity.These findings could contribute to the development and utilization of hypoallergenic BP products.

Effects of Potassium-Solubilizing Bacteria on Growth, Antioxidant Activity and Expression of Related Genes in Fritillaria taipaiensis P. Y. Li

This study aimed to examine the effects of inoculating Fritillaria taipaiensis P.Y.Li leaves with different strains ofpotassium-solubilizing bacteria (KSB), or combinations thereof, focusing on aspects of photosynthesis and physiologicaland biochemical characteristics. At present, some studies have only studied the rhizosphere microbialcommunity characteristics of F. taipaiensis and have not discussed the effects of different microbial species on thegrowth promotion of F. taipaiensis. This paper will start from the perspective of potassium-solubilizing bacteria toconduct an in-depth study. Seed cultivation commenced at the base with three different KSBs in early October2022. The growth of F. taipaiensis leaves was observed after different treatments. Both single-plant and compoundinoculations were executed. A total of eight treatment groups were established, with aseptic fertilizer and sterilizedsoil functioning as the control group. The results reveal that intercellular CO_(2) concentration (Ci), stomatal conductance(Gs), and transpiration rate (Tr) were at their apex in the S7 group. Most treatment groups exhibited anincrease in leaf area, photosynthetic pigment content, soluble sugar, soluble protein, Superoxide Dismutase(SOD), Peroxidase (POD), Catalase (CAT) activities, and proline content. The expression levels of POD, SOD,and CAT genes were evaluated, following inoculation with different KSB. The highest was the S7 group. Theinoculation with various KSB, or combinations thereof, appears to bolster the growth and development of F. taipaiensis.The composite inoculation group S7, comprising Bacillus cereus, Burkholderia cepacia, and Bacillus subtilis,manifested the most favorable impact on the diverse indices of F. taipaiensis, thereby furnishing valuableinsights for the selection of bacterial fertilizer in the artificial cultivation of F. taipaiensis.

Effects of Inoculation with Phosphate Solubilizing Bacteria on the Physiology,Biochemistry,and Expression of Genes Related to the Protective Enzyme System of Fritillaria taipaiensis P.Y.Li

Fritillaria taipaiensis P.Y.Li is a widely used medicinal herb in treating pulmonary diseases.In recent years,its wild resources have become scarce,and the demand for efficient artificial cultivation has significantly increased.This article is the first to apply phosphate solubilizing bacteria isolated from the rhizosphere soil of F.taipaiensis P.Y.Li to the cultivation process of F.taipaiensis P.Y.Li.The aim is to identify suitable reference strains for the artificial cultivation and industrial development of F.taipaiensis P.Y.Li by examining the effects of various phosphate solubilizing bacteria and their combinations on photosynthesis,physiological and biochemical properties,and gene expression related to the protective enzyme system in F.taipaiensis P.Y.Li.The experiment,conducted in pots at room temperature,included a control group(CK)and groups inoculated with inorganic phosphorussolubilizing bacteria:W1(Bacillus cereus),W2(Serratia plymuthica),W12(Bacillus cereus and Serratia plymuthica),and groups inoculated with organophosphorus-solubilizing bacteria:Y1(Bacillus cereus),Y2(Bacillus cereus),Y12(Bacillus cereus and Bacillus cereus),totaling seven groups.Compared to CK,most growth indices in the bacterial addition groups showed significant differences,with W12 achieving the highest values in all indices except the leaf area index.The content of photosynthetic pigments,photosynthetic parameters,and osmoregulatory substances increased variably in each bacterial treatment group.W12 exhibited the highest content of chlorophyll a and soluble protein,while W1 had the highest free proline content.The activities of peroxidase(POD),superoxide dismutase(SOD),and catalase(CAT)in all inoculated groups were higher than in CK,with significant changes in SOD and CAT activities.The malondialdehyde(MDA)content in all inoculated groups was lower than in CK,with Y12 being the lowest,at approximately 30%of CK.Gene expression corresponding to these three enzymes also increased variably,with POD expression in Y2 being the highest at 2.73 times that of CK.SOD and CAT expression in Y12 were the highest,at 1.84 and 4.39 times that of CK,respectively.These results indicate that inoculating phosphate solubilizing bacteria can enhance the growth of F.taipaiensis P.Y.Li,with the mixed inoculation groups W12 and Y12 demonstrating superior effects.This lays a theoretical foundation for selecting bacterial fertilizers in the cultivation process of F.taipaiensis P.Y.Li.

Repurposing Loperamide as an Anti-Infection Drug for the Treatment of Intracellular Bacterial Pathogens

Infections caused by intracellular bacterial pathogens are difficult to treat since most antibiotics have low cell permeability and undergo rapid degradation within cells.The rapid development and dissemination of antimicrobial–resistant strains have exacerbated this dilemma.With the increasing knowledge of host–pathogen interactions,especially bacterial strategies for survival and proliferation within host cells,host-directed therapy(HDT)has attracted increased interest and has emerged as a promising antiinfection method for treating intracellular infection.Herein,we applied a cell-based screening approach to a US Food and Drug Administration(FDA)-approved drug library to identify compounds that can inhibit the intracellular replication of Salmonella Typhimurium(S.Typhimurium).This screening allowed us to identify the antidiarrheal agent loperamide(LPD)as a potent inhibitor of S.Typhimurium intracellular proliferation.LPD treatment of infected cells markedly promoted the host autophagic response and lysosomal activity.A mechanistic study revealed that the increase in host autophagy and elimination of intracellular bacteria were dependent on the high expression of glycoprotein nonmetastatic melanoma protein B(GPNMB)induced by LPD.In addition,LPD treatment effectively protected against S.Typhimurium infection in Galleria mellonella and mouse models.Thus,our study suggested that LPD may be useful for the treatment of diseases caused by intracellular bacterial pathogens.Moreover,LPD may serve as a promising lead compound for the development of anti-infection drugs based on the HDT strategy.

Performance Parameters:Demobilization Antibiotic Resistant Bacteria(ARB)and Carrying Genes(ARG)in Wastewater Disinfection

The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacterial control.The influence of some parameters in quantification and performance influencing of pathogen demobilization could be considered in disinfection of wastewater.The comparison of Polyvalent phage(NE1)versus Coliphage(NE4)in suppressing a bacterium Escherichia coli(NDM-1:b-lactam-resistant)with UV irradiation was observed the efficacy in reduction of cells in the disinfection and parameter process.The results with the effect of UV-C irradiation on NDM-1 infected with 1%of NE4 showed a decrease of cells from 8×10^(6)to 2×10^(5)in 60 min with UV-C dose.The NDM1(E.coli)was infected with 1%of NE4(Polyvalent Phage)under magnetic stirring for 1 h,the cells count was 8×10^(6).After 1 h in UV-C e×posure,the cells number reached 3×10^(5).The NDM1 that was e×posed in 1 h of UV-C irradiation and then was infected with 1%of NE4.Cells counting were done 24 h after this procedure.These cells were e×posed in UV-C and showed a reduction in the number of cells from 1×10^(8)to 4×10^(5)after 60 min.The results indicate that bacteriophages can mitigate bacteria species,and combined the conventional water disinfection technologies that can support the microbial safety control strategies.

平胃胶囊对恶变后GES-1细胞氧化应激的抑制作用及机制研究

目的:观察平胃胶囊对亚硝酸胺类化合物N-甲基-N’-硝基-N-亚硝基胍(N-methyl-N’-nitro-N-nitrosoguanidine,MNNG)诱导的胃癌前病变(precancerous lesions of gastric cancer,PLGC)细胞模型的影响,并初步探讨其作用机制。方法:制备空白血清和平胃胶囊含药血清备用;MNNG诱导人胃黏膜上皮细胞系GES-1制备PLGC细胞模型,采用倒置显微镜观察细胞形态,免疫荧光法检测增殖细胞相关抗原Ki67的表达水平,进行模型评价。CCK-8法筛选含药血清最佳干预浓度及时间;采用荧光探针DCFH-DA检测细胞内活性氧(reactive oxygen species,ROS)含量;ELISA检测丙二醛(malondialdehyde,MDA)含量;采用相关试剂盒检测超氧化物歧化酶(superoxide dismutase,SOD)和谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)活性;采用新型荧光探针JC-10检测细胞线粒体膜电位的变化;采用实时荧光定量PCR检测Ki67和黑色素瘤分化相关基因7(melanoma differentiation-associated gene-7,MDA-7)的mRNA表达水平;采用Western blot法测定Ki67、白细胞介素6(interleukin-6,IL-6)和MDA-7的蛋白表达水平。结果:与正常组相比,模型组和空白血清组ROS和MDA含量显著升高(P<0.01),SOD和GSH-Px的活性显著降低(P<0.01),线粒体膜电位显著下降(P<0.01),Ki67和IL-6蛋白表达显著升高(P<0.01),MDA-7蛋白表达显著下降(P<0.01);与空白血清组相比,模型组ROS和MDA含量,SOD和GSH-Px活性,Ki67和MDA-7 mRNA表达水平,Ki67、IL-6和MDA-7蛋白表达水平,以及线粒体膜电位均无显著差异(P>0.05);与空白血清组相比,平胃胶囊含药血清组中ROS和MDA含量显著降低(P<0.01),SOD和GSH-Px活性显著上升(P<0.05),线粒体膜电位显著升高(P<0.01),Ki67和IL-6蛋白表达水平显著下降(P<0.01),MDA-7的mRNA及蛋白表达水平显著升高(P<0.01)。结论:平胃胶囊可显著减轻MNNG诱导的胃黏膜上皮细胞氧化应激损伤和炎症反应,调控促癌基因和抑癌基因的表达,从而发挥防治PLGC的作用。

山橿中生物碱类成分Laetanine、Launobine对乙酸致GES-1细胞损伤的保护作用及机制

目的利用乙酸建立胃黏膜上皮细胞(GES-1细胞)损伤模型,研究山橿中生物碱类成分Laetanine、Launobine对GES-1细胞损伤的保护作用及机制。方法通过MTT细胞增殖/毒性实验确定Laetanine、Launobine的最佳给药浓度。分别以浓度为0.01%~0.2%的乙酸培养液作用于GES-1细胞,作用时间分别为3、4、5h,筛选最佳造模条件。利用乙酸建立GES-1细胞损伤模型,测定Laetanine、Launobine含药培养基处理后的细胞存活率;Griess法测定细胞上清液中NO的浓度;ELISA法测定各组细胞上清液中肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)和前列腺素E2(PGE2)水平;WST-1法检测各实验组超氧化物歧化酶(SOD)抑制率,计算SOD活力值。结果0.1%乙酸溶液处理3h为GES-1细胞损伤的最佳造模条件;与模型组比较,Laetanine、Launobine给药组均能显著升高GES-1细胞存活率(P<0.01);经Laetanine、Launobine处理后,细胞上清液中的NO、TNF-α、IL-6和PGE2水平显著降低,SOD活力显著升高(P<0.01或P<0.05)。结论山橿中生物碱类成分Laetanine和Launobine均能保护乙酸损伤的GES-1细胞,减轻GES-1细胞的受损程度,其作用机制可能与其降低NO、TNF-α、IL-6和PGE2水平,升高SOD水平有关,表明Laetanine和Launobine可能为山橿发挥抗胃溃疡作用的有效成分。

The succession of fecal bacterial community and its correlation with the changes of serum immune indicators in lambs from birth to 4 months

Early bacterial colonization and succession within the gastrointestinal tract have been suggested to be crucial in the development of host immunity.In this study,we have investigated the changes in live weight and concentrations of selected serum parameters in relation to their fecal bacterial communities as determined by high throughput sequencing of the 16S r RNA gene over the same period in lambs.The results showed that lambs’growth performance,the serum parameters,fecal bacterial community and fecal bacterial functions were all affected(P<0.05)by age of the lambs.Similarity within age groups of fecal microbiota was lower in the preweaning period and increased sharply(P<0.05)after weaning at 60 days.The similarity between the samples collected from birth to 90 days of age and those collected at 120 days of age,increased(P<0.05)sharply after 30 days of age.Some age-associated changes in microbial genera were correlated with the changes in concentrations of immune indicators,including negative(P<0.05)correlations between the relative abundance of Lachnospiraceae UCG-010,Eubacterium coprostanoligenes group,Ruminococcaceae UCG-005,Ruminococcaceae UCG-009,Ruminococcaceae UCG-013,Ruminiclostridium 6,Ruminococcaceae UCG-008,and Oscillibacter with serum concentrations of lipopolysaccharide(LPS),D-lactate dehydrogenase(DLA),immunoglobulin(IgA,IgM,and IgG),and cytokines(interleukin-1β(IL-1β),IL-6,IL-12,and IL-17),tumor necrosis factor-α(TNF-α),and the relative abundance of these genera increased from 45 days of age.In conclusion,these results suggested that the age-related abundances of particular genera were correlated with serum markers of immunity in lambs,and there might be a critical window in the period from birth to 45 days of age which provide an opportunity for potential manipulation of the fecal microbial ecosystems to enhance immune function.

基于gE蛋白的羊伪狂犬病病毒间接ELISA的建立与应用

为建立羊源伪狂犬病病毒(Pseudorabies virus,PRV)抗体的检测方法,从PRV中对gE基因进行克隆,并构建重组载体对gE蛋白进行原核表达,以重组gE蛋白为包被抗原,建立PRV抗体间接ELISA检测方法,并进行临床样本检测。结果显示,重组gE蛋白大小为42 ku,以包涵体形式表达;Western blot检测表明重组蛋白具有良好的反应原性;重组蛋白作为包被抗原的最佳工作浓度为1μg/mL,待检血清100倍稀释,以HRP标记的兔抗山羊IgG 10000倍稀释作为二抗;检测临床样本时判定阴阳性的临界值为0.284;灵敏性试验结果显示,羊PRV阳性血清稀释2048倍时检测结果仍为阳性;批内变异系数(2.45%~5.00%)与批间变异系数(2.55%~7.41%)均小于10%;采用建立的方法检测其他常见羊源病毒阳性血清结果均为阴性;对收集的376份临床羊血清进行检测,PRV阳性率为10.6%。建立的间接ELISA检测方法可用于羊源样本中伪狂犬病病毒抗体的检测,该方法的建立为羊场PRV抗体检测提供了技术支持。

3D printed lactic acid bacteria hydrogel:cell release kinetics and stability

In this study,a new type of 3 D printed living biological hydrogel was developed by integrating lactic acid bacteria(LAB)into biocompatible and non-toxic polymer materials.Interestingly,the living materials loaded with LAB can be freeze-dried and reused for more than 100 times.The bio-hydrogel can be used to co-culture different LAB and keep its fermentation performance stable in long-term use.The release kinetics model and response surface method were used to simulate and optimize the bacteria release mode in the bio-hydrogel.The results show that the release of bacteria from hydrogel is regulated by the coupling of Fickian diffusion and polymer swelling.The stability of LAB hydrogel was evaluated by reuse experiments.The images of confocal microscopy and scanning electron microscope showed that the bacteria with high cell viability were distributed in the hydrogel and intact structure of the living hydrogel was maintained after 100 times of reuse as yoghurt starter.In conclusion,the 3 D printed LAB bio-hydrogel developed in this study has the advantage of reuse and sustainability,which is expected to open up a new way for the preparation of food culture starter.

GE LightSpeed Pro 16 CT伪影故障维修3例

介绍了GE LightSpeed Pro 16 CT的组成,分析了该设备出现的3例伪影故障的现象、原因并提出了具体的排除方法,为临床工程人员维修类似故障提供了参考。

七星关区耕地土壤Ge地球化学特征及其与作物的吸收关系

掌握耕地土壤Ge含量特征及其与作物的吸收关系,对耕地Ge的开发利用及科学选种具有重要意义。为此,以贵州省七星关区土地质量地球化学调查评价项目数据为基础,统计Ge的地球化学参数,分析该区土壤Ge地球化学特征和作物对Ge的吸收规律。结果显示:七星关区耕地土壤Ge含量在(0.86~2.48)×10^(-6),平均值1.74×10^(-6),与全国土壤Ge背景值相当。通过地统计分析,圈定富Ge耕地面积65853.54 hm^(2),占全区耕地总面积的47.41%,主要分布于研究区西北和西南部。农作物对土壤Ge的生物吸收系数(Ax)均小于1%,均处于极弱摄取水平。采用相关分析等方法讨论耕地土壤富Ge成因及影响作物吸收Ge的环境因子,得出以下结论:①土壤Ge含量主要受成土母质控制,同时受到风化成土过程的影响,并在七星关区耕地有机质含量丰富和偏酸性的土壤背景下,造成土壤Ge富集;②酸性土壤中,作物对土壤Ge的生物吸收系数(Ax)与pH呈弱负相关关系,而在中—碱性土壤中,作物对土壤Ge的生物吸收系数(Ax)与pH呈正相关关系,即偏酸性土壤是导致作物对Ge生物吸收能力低的原因。

Ag/Ge核壳颗粒的结构设计及红外光学特性的理论研究

为获得符合光谱选择性辐射红外隐身需求的颗粒,利用Mie散射理论和有限元仿真分别对Ag/Ge核壳结构的红外光学特性进行计算。研究了不同Ag内核和Ge外壳尺寸组合下颗粒消光效率峰值随波长的变化。在6.5μm等值线上等间隔的选取不同尺寸组合,通过对比消光效率曲线确定了0.3/0.848μm的核壳结构为主要研究对象。不同计算方法获得的消光效率曲线形状十分近似,消光峰均位于6.5μm处,消光效率峰值分别为16.6和16.1,验证了计算结果的可靠性。对比颗粒在不同波长入射场下的三维远场辐射及电磁功率损耗情况,发现其在6.5μm处具有更强的辐射强度和功率损耗密度,说明此时颗粒与入射场能够发生强烈的共振作用,可用于该波段红外辐射的选择性吸收。