Profiling a New Postbiotic Product for Its Application in Fish Aquaculture

Abstract

Weissella cibaria is a lactic acid bacteria that has been receiving great interest in the last decade; however, its research into aquaculture remains insufficient. In this context, the resistance to pH 3–5, bile salts (10–20%), hydrophobicity, and carbohydrate metabolisms of two W. cibaria strains isolated from rainbow trout were evaluated. At the same time, the postbiotic products of both W. cibaria were produced under different conditions, and their stability to heat (95–130 °C) and proteolytic enzymes were determined. The low pH sensitivity of two pathogens (Aeromonas salmonicida subsp. salmonicida and Yersinia ruckeri) was also recorded. Both strains of W. cibaria survived pH and bile salt treatments. Neither expressed enzymatic activity or hydrophobic characteristics with the executed methods. Treatment with heat, enzymes, and transfer to vegetal broth significantly reduced (p < 0.05) the postbiotic product’s antibacterial activity. On the other hand, no significant difference (p < 0.05) was reported in antibacterial characteristics when postbiotics were produced by coculturing both strains. Low pH does not significantly influence pathogen growth (p < 0.05). Our findings suggest that the studied strains do not adjust as probiotics, but the postbiotic product obtained from them could become a promising tool as a supplement food for fish aquaculture applications.