Study On The Antibacterial Properties Of Lactobacillus Pentosus S1-4 And Its Application In Feed

The characteristics of antibacterial substances produced by Lactobacillus pentosus S1-4,which were isolated from traditional fermentation food in Inner Mongolia,were studied.Meanwhile the effect of the strain on the feed storage was discussed.The results were showed as follows:(1)The metabolites of S1-4 were still of antibacterial activity after acid neutralization and catalase treatment. And they were sensitive to papain,trypsin and pepsin.It is presumed that the antimicrobial substance is a protein substance.(2) By the double-layers agar and diffusion method,the antibacterial diameter of the fermentation supernatant of strain S1-4 was 13.46±1.46mm(Protein concentration is 0.035mg/mL).The antimicrobial substances of strain S1-4 was isolated by pH adsorption-release method, ammonium sulfate precipitation method and ethanol precipitation method.The experimental results of ethanol precipitation method is the best,its antibacterial diameter was 32.09±0.2mm (Protein concentration is 0.132 mg/mL).Single factor and orthogonal experiments were carried out to optimize the separation conditions of antibacterial substances and the best separation conditions arerthe precipitation pH is 5,the ethanol concentration is 95%,the precipitation time is 6h,the solid-liquid ratio is 1:4.After optimization,The antibacterial diameter of the isolated solution was 39.46 ±0.23mm(Protein concentration is 0.175 mg/mL)(3)The antimicrobial substances of strain S1-4 by Tricine-SDS-PAGE electrophoresis to determination of the molecular weight of 3.5kDa.(4)The fermentation broth of the strain S1-4 with different ratio was injected into the feed,with the increase of the concentration of bacteria,total number of bacteria and molds can be suppressed in feed.