Isolation and Characterization of Antimicrobial Peptides Isolated from Brevibacillus halotolerans 7WMA2 for the Activity Against Multidrug-Resistant Pathogens

Multidrug resistance to pathogens has posed a severe threat to public health. The threat could be addressed by antimicrobial peptides (AMPs) with broad-spectrum suppression. In this study, Brevibacillus halotolerans 7WMA2, isolated from marine sediment, produced AMPs against Gram-positive and Gram-negative bacteria. The AMPs were precipitated by ammonium sulfate 30% (w/v) from culture broth and dialyzed by a 1 kDa membrane. Tryptone Soy Agar (TSA) was used for the cultivation and resulted in the largest bacteria-inhibiting zones under aerobic conditions at 25 °C, 48 h. An SDS-PAGE gel overlay test revealed that strain 7WMA2 could produce AMPs of 5-10 kDa and showed no degradation when held at 121 °C for 30 min at a wide pH 2-12 range. The AMPs did not cause toxicity to HeLa cells with concentrations up to 500 µg/mL while increasing the arbitrary unit up to eight times. The study showed that the AMPs produced were unique, with broad-spectrum antimicrobial ability.