A Spore-Forming Bacillus Strain FM2 Isolated from Fish Market Runoffs with Remarkable Probiotic Attributes for...

Area of Science:

• Aquatic microbiology
• Probiotics in aquaculture
• One Health initiatives

Background:

• Aquaculture faces challenges with fish health and antibiotic use.
• Probiotics offer a sustainable strategy to improve fish well-being and reduce antibiotic reliance.
• The One Health approach emphasizes the interconnectedness of human, animal, and environmental health.

Purpose of the Study:

• To isolate and characterize novel spore-forming probiotic bacteria from fish market drain water for aquaculture.
• To evaluate the potential of selected isolates as functional probiotics for fish.
• To identify a safe and effective probiotic strain for commercial aquaculture applications.

Main Methods:

• A multi-tiered plate-based screening methodology was used to isolate potential probiotic strains.
• Isolates were screened for non-pathogenicity, extracellular enzyme production, bile salt tolerance, and biofilm formation.
• The most promising isolate, Bacillus sp. strain FM2, was identified using 16S rRNA gene sequencing and comprehensively characterized.

Main Results:

• Three isolates (FM1, FM2, FM4) showed positive performance in initial screening.
• Bacillus sp. strain FM2 exhibited high sporulation efficiency (91%) and yield (9.3 × 10^8 CFU/mL).
• Strain FM2 demonstrated broad-spectrum antimicrobial activity against fish pathogens, inhibited biofilm formation, possessed excellent adhesive properties, antioxidant activity, and exopolysaccharide production. Its spores showed resistance to environmental and gastrointestinal stresses.

Conclusions:

• Bacillus sp. strain FM2 is a promising, safe, and multi-functional probiotic for aquaculture.
• It can improve fish gut health, inhibit common fish pathogens, and withstand challenging environmental conditions.
• Strain FM2 has significant potential for commercialization in sustainable aquaculture practices.