Antibacterial Characteristics Of Enterococcus Faecium And Its Application In Vinegar

In this paper,a strain of lactic acid bacteria producing antimicrobial substance as the research object,the preliminary optimization of its medium used as a microecological agent,the characteristics and composition of the antimicrobial substance produced,and its antimicrobial substance was applied to the storage of vinegar,to provide information for the search of new biological preservatives,the resμLts are as follows.The bacteriostatic activity of the fermentation broth of a probiotic lactic acid bacteria was measured by AGAR pore method.It was found that the fermentation supernatant of the strain had obvious bacteriostatic effect on all the six indicator bacteria used.The strain was identified by morphological observation,physiological and biochemical identification,16Sr DNA sequencing,etc.The identification resμLts showed that the strain was Enterococcus faecium.Enterococcus faecium is a kind of common strains of probiotics,from the perspective of cost saving,in does not affect the premise of the largest number of living bacterium,to the cμLtivation of the strain medium is optimized,the optimized medium for:polysorbate 80 1 ml,peptone 10.0 g,5 g of sodium acetate,beef powder 6.0 g,K₂HPO₄2.0 g,ammonium citrate 2 g,16.0 g of glucose,Mg SO₄·7H₂O 0.2 g,yeast extract 4 g,Mn SO₄·4H₂O 0.5g,deionized water 1000m L,p H6.8-7.2.The conditions for producing antibacterial substances of Enterococcus faecium were optimized.The resμLts were as follows:ammonium citrate 10.0 g,glucose 15.0 g,Mg SO₄·7H₂O 0.05g,Mn SO₄·4H₂O 0.0125g,sodium acetate 5g,beef powder 6.0 g,yeast extract 4 g,K₂HPO₄2.0 g,deionized water 1000m L,p H6.8-7.2.CμLture at 37℃for 12h.The characteristics and components of the antimicrobial substance produced by this strain were studied.It was found that the antimicrobial substance produced by this strain might consist of a variety of organic acids and small molecμLar peptides.Compared with the untreated control group,the antimicrobial activity of these compounds was not significantly different after 40min treatment at 40℃to 121℃,p>0.05.After UV radiation for 120min,the antibacterial activity did not change significantly,p>0.05.But it’s sensitive to p H-value,when the p H is less than 5,it had good antibacterial activity,no antibacterial activity at p H6～10,and weak antibacterial activity at p H11～12.The preliminary study on the properties of antibacterial components showed that the hydrooxidase treatment had no significant effect on the antibacterial activity,and there was no significant difference between the pepsin treatment and the trypsin treatment,but the papain treatment reduced the antibacterial activity by 5.58%.Using lactic acid,hydrochloric acid,formic acid,acetic acid and citric acid with the same p H value as the control,it was found that only acetic acid showed antibacterial activity to indicator bacteria,and its antibacterial activity was 52.77%of that of distillate.The fermentation broth of Enterococcus faecium was added to the vinegar with low acidity,and there was no significant difference between the fermentation broth group and the potassium sorbate group in maintaining the physical and chemical indexes of vinegar,such as sensory properties,total acid,non-volatile acid,soluble solids,etc.All of them had good effects,which were better than the blank control group without preservatives.In terms of inhibiting the growth of spoilage microorganisms,there was no significant difference between the fermentation broth group and the potassium sorbate group,and both groups had good effects,which were better than the blank control group without preservative.Therefore,it can be seen that Enterococcus faecium fermentation broth has a good effect in the preservation of vinegar.