Marine protease-producing bacteria as potential probionts for advancing mariculture

The research delves into the isolation and characterization of protease-producing bacteria from seawater, sediment, and the gastrointestinal tracts (GITs) of Snubnose pompano (Trachinotus blochii) for potential use as probiotics in marine finfish culture. Five bacterial strains screened from the marine environmental samples-Chryseobacterium indologenes Chryseobacterium culicis, Bacillus aerius, Bacillus altitudinis, and Bacillus pumilus were isolated and characterized both phenotypically and genotypically. Protease activity was assessed across acidic to alkaline pH levels (5–10) and temperatures (20 °C–120 °C) to identify the optimum conditions. B. pumilus, isolated from the GIT of T. blochii, exhibited the highest protease activity (0.088 Unit/ml) at pH 6 and 40 °C, making it a particularly potent strain. B. altitudinis and B. aerius also demonstrated significant protease activity at pH 7, with values of 0.086 Unit/ml and 0.081 Unit/ml, respectively. The in vitro study suggests that all three Bacillus strains, have the potential to serve as probiotics in marine finfish mariculture, emphasizing B. pumilus due to its superior protease activity under defined conditions. This research contributes to the development of tailored probiotics for improving protein digestibility in mariculture systems, advancing sustainable practices in marine finfish production.