Research Article: Isolation and identification of autochthonous potential probiotic candidates from the gastrointestinal tract of Caspian striped mullet (Mugil cephalus)

This study aimed to screen and identify potential probiotic strains from the gastrointestinal tract of Caspian striped mullet (Mugil cephalus). Eight out of forty isolates showed antibacterial activities against fish-associated pathogens: Yersinia ruckeri, Salmonella enterica, Escherichia coli O۱۵۷:H۷, and Staphylococcus aureus. Biochemical tests showed that ۵۰% of the isolates were capable of glucose fermentation, ۷۵% fermented arabinose, ۳۷.۵% and ۶۲.۵% were able to metabolize raffinose and mannitol, respectively. None of the eight isolates demonstrated the ability to ferment all tested sugars. The isolates demonstrated tolerance to a high bile concentration (۴۰۰۰ mg/L) as well as to mildly acidic and alkaline pH conditions. Three isolates exhibited۱۰۰% sequence identity with Carnobacterium maltaromaticum. One of the isolates exhibited ۹۹% sequence identity with Carnobacterium divergens. Two isolates exhibited ۷۱% sequence identity with Weissella koreensis and other Weissella species. Sequencing analysis revealed that the fish gut isolates are closely related to lactic acid bacteria, particularly C. maltaromaticum and C. divergens. The results indicate that the isolates have potential as probiotics in aquaculture due to ability to enhance gut health and suppress pathogenic bacteria.

کلیدواژه ها:

Digestive tract ، Gene sequencing ، Mugil cephalus ، Probiotic