Screening and Evaluation In Vitro of Bacillus-Based Probiotics for Feed Additives

Area of Science:

• Animal Science
• Microbiology
• Biotechnology

Background:

• The post-antibiotic era necessitates sustainable alternatives in animal farming.
• Bacillus-based direct-fed beneficial microorganisms are crucial for this transition.
• Probiotic feed additives offer a promising solution for animal health and productivity.

Purpose of the Study:

• To screen and evaluate Bacillus strains for probiotic potential as feed additives.
• To characterize selected strains for in vitro probiotic properties and safety.
• To assess whole-genome data for potential risks and confirm probiotic suitability.

Main Methods:

• Screened 394 Bacillus strains for extracellular enzyme production and antibacterial activity.
• Selected two Bacillus velezensis strains (FJAT-10508 and FJAT-13563) for further evaluation.
• Conducted in vitro probiotic characterization, safety assessments, and whole-genome analysis.

Main Results:

• Both selected strains demonstrated safety, lacking cytotoxicity, invasion, and mobile antibiotic resistance genes.
• High endospore formation (72.4-90.8%) and aggregation abilities (auto: 74-85%, co: 52-82%) were observed.
• Strains showed significant tolerance to simulated gastrointestinal conditions (pH 2.0, 0.3% bile salts).

Conclusions:

• Bacillus velezensis FJAT-10508 and FJAT-13563 possess robust in vitro probiotic properties.
• These strains are safe and resilient, suitable for application as feed additives.
• They represent promising Bacillus-based solutions for sustainable animal agriculture.