Partial purification and characterization of bacteriocin from novel Brevibacillus borstelensis sp. isolated from Donkey’s lactation

The heightened awareness of ensuring enhanced safety standards is growing in order pertaining to the avoidance of chemical food preservation. Concurrently, there is a discernible increase in the prevalence of antimicrobial resistance among foodborne pathogens, which engenders infections such as food poisoning, gastro-intestinal infections etc.. In this regard, bacteriocins present themselves as a compelling alternative for achieving both preservation and safety objectives in the realm of food science. Bacteriocins are ribosomally synthesized proteins that demonstrate inhibitory activities against a diverse spectrum of undesirable microorganisms. In the present study, a bacterium (Brevibacillus borstelensis sp.) derived from Donkey milk was scrutinized for its ability to generate a bacteriocin-like inhibitory substance (BLIS). The effectiveness of this substance was assessed against pathogens linked to foodborne/spoilage, specifically Bacillus subtilis (KK01), Staphylococcus aureus (MRSA) ,Pseudomonas aeruginosa (HCS36), and Escherichia coli (O22) .The evaluation comprised the bit/disc method followed by the Well-diffusion method. Employing a combination of phenotypic, biochemical, and molecular characteristics, including the 16S rRNA gene technique, the bacterial isolate was identified as Brevibacillus borstelensis strain 3.1 OR272522.1. The Bacteriocin-like inhibitory substance produced by B. borstelensiswas purified for the first time by using the chloroform extraction method, unveiling a molecular mass of 56 kDa. Further analysis examined the BLIS reactions to temperature, pH, proteolytic enzymes, and stability. The Bacteriocin-like inhibitory substance exhibited thermo-stability up to 90 °C, activity at neutral pH, sensitivity to trypsin, and partial stability up to 15 days of storage, indicating its potential as a bio-preservative for food.