| Gymnocypris przewalskii is kind of cold-water fish from highland of Lake Qinghai, which is susceptible to a variety of pathogenic bacteria and parasites during the freshwater migration stage. Isolating and screening facultative anaerobic strains from the gut microbiota of G. przewalskii, and selecting the potential probiotics to be used to regulate gut microbiota composition has significance for improving the survival rate of G. przewalskii. One potential strain was screened from gut microbiota of G. przewalskii, YC4, which had the best inhibitory effect on six common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus, was selected and identified by 16S rRNA sequencing as Enterococcus hirae. The strain could utilize multiple carbon sources, grow fast under anaerobic conditions at 0.1% (Mass Concentration) bile salt concentration, and five short-chain fatty acids, including acetic acid, propionic acid, isobutyric acid, butyric acid and valeric acid, could be detected in the culture supernatant. The artificial regression infection experiment confirmed that it is non-pathogenic, and can be used as a probiotic for the regulation of gut microbiota of G. przewalskii and other fish. |
