Characteristic changing of Brevibacillus laterosporus SA14 by ultraviolet and chemical mutagenesis

Brevibacillus laterosporus SA14 , Gram-positive spore-forming bacterium, could produce biocompounds which inhibit the growth of Gram-positive cocci in cluster ( Staphylococcus aureus ) , including methicillin - resistant Staphylococcus aureus ( MRSA ) . The characteristic changing of this bacterium was done by random mutagenesis, using ultraviolet (UV) or 1-hexyl-3-nitro-1-nitrosoguanidine ( NTG ) . Five mutants were isolated, three from UV mutagenesis, named as UV1, UV2, LZ1; and two from chemical mutagenesis, named as NTG1, NT8. The cells and culture broth of all mutants could inhibit the growth of indicating bacteria, Staphylococcus aureus TISTR 517 and Bacillus subtilis ATCC 6633 and still had hemolytic activity when tested by means of spot on lawn and agar well diffusion. The mutant cells were less resistant to acid, oxgall bile and antibiotics than those of wild type ( SA 14 ) . However, only culture broth of LZ1 mutant gave the least hemolytic activity. It may be used for further study as a model to develop the antimicrobial drugs.