Effects of probiotic on microfloral structure of live feed used in larval breeding of turbot Scophthalmus maximus

The effects of an exogenous probiotic( Bacillus amyloliquefaciens) on microbial community structure of B ranchionus plicatils and A rtemia sinica were evaluated in this study during turbot( Scophthalmus maximus) larval breeding. The analysis and comparison of the microfloral composition of live feed with probiotic was conducted using the Illumina HiSeq PE250. The abundance of microbial species and diversity of microflora in live feed with B. amyloliquefaciens were higher than those in the control. The microfloral composition was similar among the three replicate experimental groups of B. plicatils compared with the control after enrichment. L actococcus, Pseudoalteromonas, and Alteromonas were always dominant. Additionally, some other bacterial species became dominant during the enrichment process. The microbial community during nutrient enrichment of A. sinica was rather similar among the three control replicates. Relative abundance of Cobetia sp., the most dominant species, was 54%–65.2%. Similarity in the microbial community was still high after adding B. amyloliquefaciens. Furthermore, P seudoalteromonas and Alteromonas replaced Cobetia as the dominant species, and the abundance of Cobetia decreased to 4.3%–25.3%. Mean common ratios at the operational taxonomic unit level were 50%–60% between the two B. plicatils and A. sinica treatments. Therefore, the microbial community structure changed after adding B. amyloliquefaciens during nutrient enrichment of B. plicatils or A. sinica and tended to stabilize. Additionally, the abundance of V ibrio in any kind of live feed was not significantly dif ferent from that in the control. These results will help improve the microflora of B. plicatils and A. sinica and can be used to understand the multiple-level transfer role of probiotic species among probiotic products, microflora of live feed, and fish larvae.

Effects of Fructooligosaccharides, compared with Direct-Fed Microbial Bacteria,and Zinc Bacitracin on Cecal Microbial Populations and Performance of Broilers

An experiment was conducted to determine the effects of dietary fructooligosaccharides(FOS),compared with direct-fed microbial bacteria(DFM),and zinc bacitracin,on cecal microbial populations and performance of broiler Chickens.One hundred and ninety-two broilers(Avian) were randomly assigned to four groups,with four replicates of 12 birds each.The control group was fed with the basal diet,without any drug additive.FOS,DFM and zine bacitracin was respectively added to the basal diet at the level of 1.5%,800 mg·kg -1 and 300 mg·kg -1 to form the experimental diets.Body weight,feed intake and feed efficiency were measured weekly.The feeding trial started at 1 d and ended at 21 d.At day 14 and day 21,four broilers per group were killed and cecum was taken to determined microflors and pH.The results showed that dietary FOS increased bifidobactrial concentration by 1.75-fold(P<0.05) at 14 d of age and 1.45-fold(P<0.05) at 21 d of age compared with control.FOS had no effect on concnetrations of E.coli and pH.There were no dietary effects of FOS,DFM,and zinc bacitracin on weight gain,feed intake,feed conversion(P>0.05).