Biological Characteristics Of Bacillus Subtilis HJD.A32 And Its Bacteriostatic Mechanism

Bacillus subtilis HJD.A32 was a strain from the Shanxi old vinegar that could producedbroad-spectrum antibacterial bacteriocin.Based on this,the experiment studied the biological characteristics of the bacteria and the bacteriostatic mechanism of the bacteriocin produced by them.It provided a theoretical and applied basis for the development and utilization of B.subtilis HJD.A32 as a probiotic microecological preparation and biological preservative.The main findings were as follows:(1)Enzymatic method was used to analyze the enzyme production ability of Bacillus subtilis HJD.A32 by different culture methods.It was found that B.subtilis HJD.A32 has the ability to produce liquefaction enzyme,glucoamylase and protease.The enzyme production performance of solid culture is higher than that of liquid culture.The activities of saccharifying enzymes,liquefying enzymes and proteases reached 1874.23U/g,4.43U/g and 181.91U/g,respectively.(2)The strain has good tolerance.The strain was found to be tolerant to alcohol,sodium chloride and bile salt by spectrophotometry,with the highest concentration of alcohol,sodium chloride and bile salt being 8%,8% and 1%,respectively;to surfactants(SDS,LAS,AES,Tween 20 and Tween 80)within a certain range;to acid and alkali,the highest acidity was 1,and the highest p H was 12;to heat,the strain was tolerant.After being treated at high temperature of 100 °C for 5 min,it can still grow and multiply;it has certain tolerance to simulated artificial gastric juice and intestinal juice.With the prolongation of culture time,it could adapted to artificial gastric juice and intestinal fluid environment and grow and multiply.Tolerance to different types of antibiotics(aminoglycosides,macrolides,?-lactams,tetracyclines,sulfonamides,quinolones,amide alcohols,imidazoles)was found by the Oxford Cup method.(3)The bacteriostatic mechanism of Bacteriocin Produced by B.subtilis HJD.A32 was studied with Escherichia coli and Staphylococcus aureus as indicator bacteria.The spectrophotometric method was used to study the effect of crude extract of bacteriocin produced by B.subtilis HJD.A32(abbreviated as bacteriocin A32 crude extract)on the growth of indicator bacteria,the change of phosphorus content andthe permeability of cell membrane.The solubility was determined by anthrone method.The content of total sugar;the change of cell membrane permeability was observed by observing the change of conductivity;the change of soluble protein content was determined by Coomassie brilliant blue method;the effect on cell wall was studied by the determination of alkaline phosphatase content;SDS-PAGE electrophoresis was used observe the effects of protein synthesis.The results showed that the bacteriocin A32 crude extract could effectively slow the growth rate of indicator bacteria;destroy the cell membrane and cell wall of indicator bacteria,causing the cell membrane permeability to increase,and then the cell contents were leaked,so that the conductivity is increased,soluble protein,total The increase of sugar content affected the metabolism of phosphorus.At the same time,the bacteriocin A32 crude extract has a certain influence on the synthesis of bacterial proteins,which hinders the normal expression of bacterial proteins.