Isolation, characterization, and assessment of Bacillus rugosus potential as a new probiotic for aquaculture applications

Aquaculture is an important component of the world food supply and a significant source of protein. However, this industry faces numerous problems. Including poor fish feed digestion and uneconomic nutrient utilization. This can result in unsatisfactory growth rates and poor stock performance. Utilizing probiotics, which are beneficial microbes that can enhance digestive systems and general fish health, is one possible way to address these issues. This study was designed to identify and evaluate a novel strain of Bacillus as a promising probiotic. The strain of Bacillus rugosus that was examined and coded NM007 showed promising probiotic characteristics that could help fish digest and utilize their feed more efficiently, reduce feed waste, and improve their digestive systems. B. rugosus NM007 exhibited the ability to produce digestive enzymes like protease, amylase, and lipase, which are the main digestive enzymes. It showed strong auto-aggregation activity and co-aggregation activity with Aeromonas sp. and Streptococcus sp. It also demonstrated tolerance to the presence of bile salt, acidic pH, and salinity up to 60 ppt. The sensitivity analysis towards antibiotics, hemolytic activity and the safety assessment on Nile tilapia fish (Oreochromis niloticus) confirmed the safety of this isolate. Based on the findings of this investigation and the isolate's characterization, Bacillus rugosus NM007 could serve as a new promising probiotic bacterium for aquaculture.