The effects of Bdellovibrio and like organisms (BALOs) and Lactobacillus salivarius on changes in gut microbial biodiversity and their potential role on Shrimp (Litopenaeus vannamei) Postlarvae

Abstract White-leg shrimp (Litopenaeus vannamei) is the most important species in the shrimp industry, with its production virtually all from aquaculture. Nevertheless, it frequently suffers from diseases, indicating the inadequacy of existing control measures. Recent, evidence has shown that probiotics play an important role in disease control by maintaining the composition of the gut microbiota. The aim of the present work was to evaluate the probiotic potential of Bdellovibrio and like organisms (BALOs) strain BDN-1F2 and Lactobacillus salivarius strain GZPH2 in rearing shrimp postlarvae (PL) with a control group without any treatment. The results showed that compared to BDN-1F2, GZPH2 only had a better effect on length growth while BDN-1F2 performed significantly better in weight gain and survival rate (P < 0.05). The 16S high throughput sequencing results showed that BDN-1F2 was significantly more effective than GZPH2 at building a healthy gut microbial communities, including the reduction of pathogenic bacterial taxa Gammaproteobacteria/Vibrionales and the increment of beneficial bacterial taxa Alphaproteobacteria/Rhodobacteraceae. Furthermore, BDN-1F2 also lowered Firmicutes/Bacteroidetes ratios, which theoretically supported better PL growth performance in this group. In addition, the relative abundances of predicted functional microbial genes involving amino acid metabolism and carbohydrate were very high in BDN-1F2 group than in groups GZPH2 and control. To our knowledge, this is the first report to compare between two probiotics, BALOs strain BDN-1F2 and Lactobacillus salivarius strain GZPH2 and an investigation of changes in intestinal microbial community structure as well as their effects on shrimp survival and growth performance.