Investigation of Lysinibacillus macroides, Kurthia huakuii and Enterococcus faecium as potential probiotics from freshwater snail gut microbiota

For various kinds of mammals and insects, including humans, the composition and roles of intestinal microbial populations have been clarified; however, less is understood concerning the gut microbiota of mollusks. Lanistes carinatus (L. carinatus), Cleopatra , and Helisoma duryi ( H. duryi) and explore their gut microbiota. Lysinibacillus macroides ( L. macroides) , Kurthia huakuii ( K. huakuii ) and Enterococcus faecium ( E. faecium) were isolated from L. carinatus , Cleopatra and H. duryi , respectively. L. macroides , K. huakuii and E. faecium demonstrated no hemolytic and DNase activity. Furthermore, the three potential probiotic bacteria showed antimicrobial efficacy towards Staphylococcus (Staph.) aureus, Escherichia (E.) coli, Salmonella (S.) typhi and Pseudomonas (Ps.) aeruginosa . The cell free supernatant (CFS) derived from the three potential probiotics demonstrated non-significant cytotoxicity against Caco2 cells in all tested dilutions. In addition, the bacterial isolates displayed significant tolerance to a wide range of pH values and bile salt concentrations (0.3% and 0.7% w/v). The three bacterial isolates-maintained sensitivity to all tested antibiotics except for L. macroides and K. huakuii who exhibited resistance against tetracycline while K. huakuii was resistant to gentamycin. L. carinatus , Cleopatra and H. duryi gut microbiota were explored to investigate their microbial population structure where it was dominated with two main phyla with no significant difference Proteobacteria and Bacteroidetes . The purposes of the investigation were to establish the probiotic potential of L. macroides , K. huakuii and E. faecium bacterial isolates obtained from the gut microbiota of freshwater snails and their ability as a promising probiotics promoting health benefits in humans or animals.