Characterization and in-vivo evaluation of potential probiotics of the bacterial flora within the water column of a healthy shrimp larviculture system

A thorough understanding of the normal bacterial flora associated with shrimp larviculture systems contributes to probiotic screening and disease control. The bacterial community of the water column over a commercial Litopenaeus vannamei larval rearing run was characterized with both culture-dependent and culture-independent methods. A total of 27 phylotypes at the species level were isolated and identified based on 16S rDNA sequence analysis. Denaturing gradient gel electrophoresis （DGGE） analysis of the V3-V5 region of 16S rRNA genes showed a dynamic bacterial community with major changes occurred from stages zoea to mysis during the rearing run. The sequences retrieved were affiliated to four phyla, Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes, with the family Rhodobacteraceae being the most frequently recovered one. Subsequently, 13 representative strains conferred higher larval survival than the control when evaluated in the in-vivo experiments; in particular, three candidates, assigned to Phaeobacter sp., Arthrobacter sp., and Microbacteriurn sp., significantly improved larval survival （P〈0.05）. Therefore, the healthy shrimp larviculture system harbored a diverse and favorable bacterial flora, which contribute to larval development and are of great importance in exploiting novel probiotics.

Bacterial flora concurrent with Helicobacter pylori in the stomach of patients with upper gastrointestinal diseases

AIM： To investigate the non-He/icobacterpy/ori （H. pylori） bacterial flora concurrent with H. pylori infection.METHODS： A total of 103 gastric biopsy specimens from H. pylori positive patients were selected for bacterial culture. All the non-H, pylori bacterial isolates were identified by matrix assisted laser desorption ionization time-of-flight mass spectrometry （MALDI-TOF MS）.RESULTS： A total of 201 non-H, pyiori bacterial isolates were cultivated from 67 （65.0%） of the 103 gastric samples, including 153 isolates identified successfully at species level and 48 at genus level by MALDI-TOF MS. The dominant species were Streptococcus, Neisseria, Rothla and Staphylococcus, which differed fromthe predominantly acid resistant species reported previously in healthy volunteers. The prevalence of non-H. pylori bacteria was higher in non-ulcer dyspepsia group than in gastric ulcer group （100% vs 42.9%, P 〈 0.001）. Six bacterial species with urease activity （Staphylococcus epidermidis, Staphylococcus warneri, Staphylococcus capitis, Staphylococcus aureus, Brevibacteriurn spp. and Klebsiella pneumoniae） were also isolated.CONCLUSION： There is a high prevalence of the non-H, pylori bacteria concurrent with H. pylori infection, and the non-H, pylori bacteria may also play important as-yet-undiscovered roles in the pathogenesis of stomach disorders.

External Bacterial Flora and Antimicrobial Susceptibility Patterns of Staphylococcus spp. and Pseudomonas spp. Isolated from Two Household Cockroaches, Blattella germanica and Blatta orientalis

A study was performed to estimate the prevalence of the external bacterial flora of two domestic cockroaches （Blattella germanica and Blatta orientalis） collected from households in Tebessa （northeast AIgeria）.Three major bacterial groups were cultured （total aerobic, enterobacteria, and staphylococci） from 14 specimens of cockroaches, and antibiotic susceptibility was tested for both Staphylococcus and Pseudomonas isolates. Culturing showed that the total bacterial load of cockroaches from different households were comparable （P〈0.001） and enterobacteria were the predominant colonizers of the insect surface, with a bacterial load of （2.1×10^5 CFU/insect）, whereas the staphylococci group was the minority. Twenty-eight bacterial species were isolated, and susceptibility patterns showed that most of the staphylococci isolates were highly susceptible to chloramphenicol, gentamycin, pristinamycin, ofloxacin, clindamycin, and vancomycin; however, Pseudomonas strains exhibited resistance to amoxicillin/clavulanic acid, imipenem, and the second-generation antibiotic cephalosporin cefuroxime.

Heterotrophic Bacterial Floras in Industrial Area and Unpolluted Marine Environments around Qingdao

From Oct. 1999 to Oct. 2000, the heterotrophic bacterial floras in the industrial marine environment around the Qingdao Power Plant (QPP) and in the unpolluted marine environments were investigated. The results showed that the numbers of the heterotrophic bacteria around QPP were much higher than those in unpolluted environments, and the average numbers in QPP Seawater, QPP Sediment, Unpolluted Seawater and Unpolluted Sediment were 5.4×104cfu(mL) -1, 5.0×105cfug -1, 3.0×102cfu(mL) -1 and 1.3×105cfug -1 respectively. Totally, 118 strains were isolated from QPP and 99 of them were Gram-negative. One hundred and twenty one strains were isolated from the unpolluted environments and 104 of them were Gram-negative. All the Gram-negative bacteria belonged to 13 genera. The distribution of the bacteria was varied in different marine environments. The results showed that the unpolluted marine environments contained much more Vibrio than seawater and sediment around QPP.

Heterotrophic Bacterial Flora in Aquaculture Area around Xuejiadao

From Oct., 1999 to Oct., 2000, the heterotrophic bacterial flora in the aquaculture area around Xuejiadao was investigated. The result shows that the populations of the heterotrophic bacteria are heavier in summer and autumn than those in winter and spring. The average populations in seawater, sediment, the surface of seaweed and the surface of fish are 1.4×10 4 cfu mL -1, 5.4×10 6 cfu g -1, 1.5×10 6 cfu g -1 and 1.8×10 3 cfu cm -2, respectively. A total of 301 strains were isolated, among them 259 were Gram-negative. All the Gram-negative bacteria belong to 13 genera and some genera of Enterobacteriaceae. The communities of bacteria are slightly different among the samples. In the body surface of fish, Genus vibrio is dominant. In the remaining samples, dominant genus is Aeromonas.

Bacterial flora of conjunctiva after death

AIM:To evaluate the frequency of bacterial flora of conjunctiva after death(cadaver eyes) which will give information about the bacterial contamination of donor eyes,and the in-vitro sensitivity of isolated bacteria to the commonly used antibiotics in ophthalmic practice.METHODS:Conjunctival swabs were taken from the cadavers(motor vehicle accident deaths and patients who died in the hospital),within 6h after death,and sent for culture and sensitivity test.Conjunctival swabs,taken from the healthy conjunctiva of patients admitted for cataract surgery,were sent for culture and sensitivity as controls(eyes in those of living status).The bacterial isolates were tested against the commonly used antibiotics(chloramphenicol,gentamicin,ciprofloxacin) in ophthalmology practice.RESULTS:Bacteria were isolated in 41 out of 100 conjunctival swabs(41%),taken from 50 cadavers(study group).Coagulase negative staphylococcus was the most common bacteria isolated(15%),followed by pseudomonas aeruginosa(5%).Gentamicin was effective against majority of the bacterial isolates(82%).Bacteria were isolated from 7 out of 100 conjunctival swabs taken as control group(eyes in living state).Coagulase negative staphylococcus was the most common organism(5%) isolated in control group;the others were staphylococcus aureus(1%) and beta hemolyticus streptococci(1%).CONCLUSION:Bacteria were isolated from 41% of the cadaver eyes.High percentage sensitivity of the bacterial isolates to gentamicin(82%) supports the practice of thorough irrigation of the eyes with gentamicin solution before starting the procedure of enucleation followed by immersion of the enucleated eyeballs in gentamycin solution,to prevent the bacterial contamination.

Bacterial Flora of Water and Rotifers in Outdoor Mass Culture Tanks Fed with Different Microalagal Diets

Investigations were carried out on the bacterial flora of water and the quality of rotifers in outdoor mass culture tanks. Brachionus plicatilis and B. rotundiformis were cultured in 10 numbers of 1 tonne tanks and the physico-chemical parameters and microbial loads of water, and total bacterial and Vibrio loads of microalgae and rotifers, during the period 2014-15, were studied. The study revealed a significant variation of the ammonia levels and total bacterial loads with different diets （P 〈 0.05）. A positive correlation was observed between the total bacterial loads of algal concentrations and loads of rotifers, but no correlation was observed between Vibrio loads of water and rotifers. The prevalence of Vibrio loads of rotifers was low in tanks fed with Nannochloropsis oculata and maximum Vibrio loads were recorded in Chaetoceros calcitrans fed rotifers. The Vibrio loads significantly varied with days of culture and also with the algal diets. A positive correlation was observed between the total Vibrio loads of water and rotifers.

Efficacy of incremental loads of cow's milk as a treatment for lactose malabsorption in Japan

BACKGROUND Lactose intolerance(LI)is commonly seen in East Asian countries.Several studies showed that lactose or milk loading has been used as a treatment for lactose malabsorption(LM)in Western countries,but there have been no reports regarding this type of treatment in Japan.As lactose or milk loading requires ingestion of large amounts of lactose within a short period,this is considered to be too harsh for Japanese people because of their less habitual milk consumption(175 mL per day in average)than Western people.In this study,we demonstrated lactose tolerance acquisition in a suitable way for Japanese.AIM To examine the efficacy of lactose(cow’s milk)loading treatment in patients with LM.METHODS Individuals with abdominal symptoms induced by milk or dairy products(LI symptoms)were identified with a questionnaire.A 20 g lactose hydrogen breath test(LHBT)was carried out to confirm LM diagnosis and to evaluate co-existence of small intestinal bacterial overgrowth(SIBO).Respondents diagnosed with LM were selected as study subjects and were treated with incremental loads of cow’s milk,starting from 30 mL and increasing up to 200 mL at 4-7 d intervals.After the treatment,changes in symptoms and LM diagnostic value of 20 g LHBT were investigated.Stool samples pre-and post-treatment were examined for changes in intestinal microbiota using 16S rRNA sequencing.Informed consent was obtained prior to each stage of the study.RESULTS In 46 subjects with LI symptoms(10-68 years old,mean age 34 years old)identified with the questionnaire,35(76.1%)were diagnosed with LM by 20 g LHBT,and 6 had co-existing SIBO.The treatment with incremental cow’s milk was carried out in 32 subjects diagnosed with LM(14-68 years old,median age 38.5 years old).The mean period of the treatment was 41±8.6 d.Improvement of symptoms was observed in 29(90.6%;95%confidence interval:75.0%-98.0%)subjects.Although 20 g LHBT indicated that 10(34.5%)subjects had improved diagnostic value of LM,no change was observed in 16(55.2%)subjects.Analysis of the fecal intestinal microbiota showed a significant increase in Blautia in 7 subjects who became symptom-free after the treatment(P=0.0313).CONCLUSION LM was diagnosed in approximately 75%of the subjects who had LI.Incremental loads of cow’s milk is regarded as a useful treatment for LM without affecting everyday life.

Chitosan Extends the Shelf-life of Filleted Tilapia (Oreochromis niloticus) During Refrigerated Storage

Shelf-life extension of aquatic products is of significant economical importance. To determine the potential effect of chitosan on the shelf-life of filleted tilapia, this study analyzed the bacterial community diversity in fresh and spoiled tilapia fillets stored at (4 ± 1)℃ and examined the antimicrobial activity of chitosan against relevant bacteria isolates. Results showed that Pseudomonas (20%) and Aeromonas (16%) were abundant in fresh tilapia fillets, whereas Pseudomonas (52%), Aeromonas (32%) and Staphylococcus (12%) were dominant in the spoiled samples. Chitosan showed wide-spectrum antibacterial activity against bacteria isolated from tilapia and 5.0 g L-1 chitosan was selected for application in preservation. We further determined the shelf-life of chitosan-treated, filleted tilapia stored at (4 ± 1)℃ based on microbiological, biochemical and sensory analyses. Results showed that the shelf-life of chitosan-treated, filleted tilapia was extended to 12 d, whereas that of untreated, control samples was 6 d. These indicate that chitosan, as a natural preservative, has great application potential in the shelf-life extension of tilapia fillets.