Isolation Of Bacteria From Bacon Source With Broad Spectrum Antibacterial And Characterization Of Antibacterial Substances

Fermented meat products, as special meat products of ethnic minorities of Tujia and Miao, are deeply loved by people for the unique flavor. These products are traditionally fermented in natural, and therefore, a large amount of harmful bacteria are restrained by internal beneficial bacteria which are consequently good resources to filtrate suitable biology to store meat products.This paper takes fermented meat products in western Hunan as bacteria source, separating a strain of bacteria with broad spectrum bacteriostatic action on E.coli(G-), Salmonella(G-), Bacillus subtilis(G+), Bacillus cereus(G+) and Bacillus licheniformis(G+), and identifying it through physiological biochemical and molecular biological methods. After optimizing this strain of bacteria’s ability of producing antibacterial material through response surface method, this paper makes some relevant research on the antibacterial elements and comes to following conclusions.(1) Isolation and identification of bacterial species This paper uses MRS selective media, and after preliminary and second screening separates a strain of bacteria, bacterial strain LJ-3, which has significant antibacterial effect on E.coli, Salmonella, Bacillus subtilis, Bacillus cereus, and Bacillus licheniformis. The bacterial strain’s morphological features are as following:young bacteria are milk whiter and old bacteria are light yellow or dark yellow, opaque, round, smooth edge, raised, and positive in gram stain. After16S rDNA sequence analysis, the homology of this bacterial strain’s16S rDNA sequence and Lactobacillus plantarum is99%; in physiological and biochemical tests, it can be proved that this bacterial strain’s main features are similar to Lactobacillus plantarum, and therefore, it can be certain that this bacterial strain is Lactobacillus plantarum.(2) Optimization of antibacterial ability Bacillus subtilis as subjects and inhibition zone’s diameter as standard, and explores the optimal fermentation conditions and most suitable nutrient medium of elevating LJ-3to produce bacteriostatics. The test results show that the optimal nutrient elements are Ammonium Citrate Tribasic0.32g, yeast extract2.2g, glucose1.9g, the optimal fermentation condition pH6.00, fermentation temperature30℃, inoculum size5.5%. Antibacterial substances produced by LJ-3have inhibiting ability on Bacillus subtilis, and after optimization, inhibition zone diameter is31.54mm in average under fermentation condition. (3) Analysis of antibacterial substances With heat treatment, pH treatment, protease and H2O2treatment and dialysis membrane test, the analysis of Lactobacillus plantarum LJ-3antibacterial substance shows that this strain of bacteria metabolite has strong bacteriostatic ability under acidic condition, and the bacteriostatic test through HPLC separation proves that antibacterial products mainly include heat stable small molecular protein with molecular weight less than6000Da, also there are some macromolecular substances, and protease degradation test showed that protein component in the bacterial antimicrobial substance.