Production of antimicrobial substances by a novel Bacillus strain inhibiting Salmonella Typhimurium

- Bacillus sp. ZBP4 producing antimicrobials inhibit both Gram (−) and (+) pathogens.
- Carbon source limitation increases the production of the antimicrobials.
- Whey powder can be used as the sole medium to produce the antimicrobials.
- The maximum production observed at 24-26 h of the growth.

Possible alternative antimicrobials are needed to search for better way to reduce the occurrence risk of foodborne pathogens in food products. The aim of the study was to determine the antimicrobial properties of the substances Bacillus sp. ZBP4 against Gram negative (Salmonella Typhimurium, Salmonella. Enteritidis, Pseudomonas aeruginosa, and Escherichia coli O157:H7) and Gram positive (Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus) pathogens. Impact of time, temperature (30-50 °C), pH (4.0-11.0), glucose concentration (0-20 g/L), or whey powder (10-20 g/L) on the rate of the secretion of antimicrobials have been also determined using S. Typhimurium as test organism. Antimicrobial substances of Bacillus sp. ZBP4 was effective against all tested pathogens, but not P. aeruginosa. The levels of antimicrobials peaked at 24-26 h of bacterial growth. The optimum pH and temperature were determined as 8.0 and 33 °C, respectively. The highest antimicrobial production was observed in the absence of glucose, i.e. while there were only nitrogen sources. It was able to produce antimicrobials in the media containing only whey powder. Therefore, we suggest that only whey powder as a waste product can be sufficient as medium to produce satisfactory antimicrobials by Bacillus sp. ZBP4 effective against wide antimicrobial spectrum of the bacteria.