Study On Isolation And Identification Of Spora-forming Bacteria Of Meat Product And Antimicrobial Technology

Heat-resistant microbial bacteria is the key reason leading to the deterioration of meat products.Among them, spore-forming bacteria is the main microbial population,and the mechanism of heat resistance of spore-forming bacteria is of great significance to the development of practical technology. In this study, a thermotolerant bacterium was screened from the roasted chicken broth by the conventional method. The strain was identified by Biolog rapid identification and 16S rDNA sequence analysis, and the strain was identified as Bacillus subtilis. The isolated B. subtilis was subjected to heat resistance analysis to find D value and Z value :D115℃ = 8.33 min; D105℃ = 10 min; D95 ℃ = 11.36 min,Z =3.75 ℃.The bactericidal effect of B. subtilis was studied by the use of biological preservatives,acidic oxidizing potential water, high energy electron beam radiation and ozone sterilization.The bactericidal results and conclusions are as follows:(1) The available chlorine content in the newly prepared acidic oxidation potential water was 92.02 mg / L and the pH value was 2.02. With the role of liquid 20min, The killing logarithm of B. subtilis spores in the suspension can reach more than 5.5. The acid oxidizing potential water was stored at 40℃ for 10 days,and its effective chlorine was reduced to 48.62mg / L and the pH value was 2.62, and the killing effect on bacterial spores was weakened. The organic matter content in the substrate had a significant effect on the germicidal effect of the acidic oxidizing potential water, and the bactericidal effect was significantly decreased with the increase of the organic concentration.(2) MICs of Nisin, lysozyme, ε-lysine and chitosan to Bacillus subtilis were 20 mg / L,40 mg / L, 40 mg / L and 80 mg / L,respectively. 40 mg / L Nisin combined with 40 mg / L lysozyme could increase the killing rate of B. subtilis by 1 times compared with Nisin alone.Nisin combined with lysozyme alone increased the killing rate of subtilis by 1 time, the killing logarithm value was 1.32, and the bactericidal effect was better than that of Nisin and traditional germinating agent L-alanine.(3) The D value of Bacillus subtilis was about 5.21 times that of B. subtilis. The germination rate of spores was increased to about 7 after irradiated by 12 KGy at 35℃.Low cell concentration was sensitive to low dose irradiation, and high concentration of cell concentration was sensitive to high dose irradiation.(4) The increase of the volume of the solution lead to the increase of ozone saturation time and the lower saturation concentration. The stability of ozone water and water temperature had a great relationship. The half-life of ozone at different temperatures: 34 min at 15 ℃; 23 min at 25 ℃; 18 min at 35℃C. 500mL solution for 30s, containing ozone amounted to 27.56mg / L, the concentration of bacteria killing rate of 99.5% or more. The bactericidal rate of 500 mL ozone suspension was lower than 96% after 60 min storage. The results showed that the bacteriostatic and bactericidal effect of the aerobic sterilization method was better than that of the suspension sterilization method.