Abstract: The fermentation supernatant of bacteriocin M14-1 was purified by sulfate precipitation and crude protein extract was obtained.High-purity product was purified by cation exchange and solid phase extraction.The bacteriocin enzyme sensitivity,pH stability,thermal stability,antimicrobial spectrum,bacteriocin production and growth of the strain were studied.Bacteriocin M14-1 was sensitive to protease K,trypsin and pepsin,but insensitive to catalase.As result of bacteriocin M14-1 poor thermal stability,inhibition activity was decreased after 121  ℃ for 15 min.The bacteriocin had good antibacterial activity in pH2.0-10.0.The antimicrobial spectrum showed that bacteriocin of L.helvetic us M14-1 only inhibited the growth of L.monocytogenes.L.helvetic us M14-1 reached stable stage for 16 h of fermentation.The optimal harvest time for bacteriocin was 12 h.

Key words: bacteriocin, Lactobacillus helveticus, physicochemical characteristics, isolation and purification