Production of Bacteriocin-like Substances by <i>Bacillus</i> Spp. JY-1 in Soy Whey

Soy whey is a by-product from the processing of soybean products, which is generally discarded and considered as waste. In recent years, a large number of bacteriocins produced by bacteria have been described. However, the production of bacteriocins in soy whey has not yet reported. Bacteriocin-like substance producing B. spp JY-1 was isolated from Chinese traditional fermented soybean (douchi) in previous study. In present study, the antimicrobial spectrum, and the effect of enzymes, pH and heat on the antibacterial activity of bacteriocin-like substance produced by B. spp JY-1 were evaluated. Then, the effects of supplement of carbon and nitrogen sources on the production of bacteriocin-like substances in soy whey were also investigated. Results obtained indicated that bacteriocin-like substance in cell-free supernatant of JY-1 exhibited broad inhibitory spectrum both against some food-borne pathogens. The bacteriocin-like substance JY-1 was sensitive to trypsin and pepsin, but stable between pH 2.0-10, and heat resistance (65-105°C). In addition, the production of bacteriocin-like substance JY-1 started at the early exphonential phase and reached its maximum at the stationary phase. The antimicrobial activity of cell-free supernatant of JY-1 cultured in soy whey was observed. The supplement of soluble starch or beef extract in soy whey yielded a higher production of bacteriocin-like substance. The results indicated that the bacteriocin-like substance JY-1 may be a potential candidate for alternative agent to control important food pathogens, and the soy whey has potential for production of bacteriocins.