Abstract: Lactobacillus plantarum D1501 was inoculated into soy whey and cultivated under static conditions at 37 ℃ for 24 h to prepare fermented soy whey (FSW). Antimicrobial tests showed that FSW had obvious antimicrobial activity against both Gram-positive and Gram-negative bacteria tested, and had weak antimicrobial activity against Candida, but exhibited no inhibitory effect on Saccharomyces cerevisiae or two mold strains tested. The bacteriostatic substance in FSW was speculated to be bacteriocin by enzymatic hydrolysis and neutralization experiments. The cell-free neutral supernatant of L. plantarum D1501 was separated by 30, 10 and 3 kDa ultra filtration tubes sequentially and concentrated by rotary evaporation. Then it was subjected to RESOURCE-Q anion exchange chromatography and reverse-phase chromatography with 300SB-C18 for further purification. The purity of the purified bacteriocin was determined to be high by high performance liquid chromatography (HPLC), and it was named as Lp100. The molecular mass of Lp100 was determined by LC-MS/MS to be approximately 1 434.90 Da, and its amino acid sequence was MCCKVLLLLSRR. The specific activity of the purified product was 7 247.00 IU/mg with 79.94-fold purification and 1% recovery.

Key words: Lactobacillus plantarum D1501; fermented soy whey; bacteriocin; purification and identification; antimicrobial activity