Screening and Identification of Lactobacillus plantarum and Studies on Its Antibacterial Substances

The strain was isolated and screened from the traditional fermented food samples with the methods of dissolving calcium ring and agar diffusion inhibition circle. The strain identification was studied by physiological characterization observation,biochemical test and 16S rDNA sequencing analysis. The analysis of antibacterial substances was carried out by enzyme sensitivity reaction,acid elimination test and HPLC detection. The antibacterial spectrum was investigated by the method of agar diffusion inhibition circle. The results showed that the strain DB was isolated from the northeast sauerkraut sample,and it was identified as Lactobacillus plantarum CNQ3.After fermentation for 24 h in MRS,the viable count of L. plantarum CNQ3 was 6.5×10¹¹ CFU/mL and the diameter of inhibitory zone against Staphylococcus aureus was 19.50 mm. The antibacterial fermentation broth of L. plantarum CNQ3 was primarily determined as organic acids. The acid compounds were analyzed by HPLC and they were mainly presented as lactic acid and acetic acid,in which the contents were 11.23 mg/mL and 5.58 mg/mL,respectively,moreover,they also contained phenyllactic acid for 0.083 mg/mL. The active compounds showed a wider antibacterial spectrum with the tested foodborne pathogens and spoilage bacteria,in which,they exhibited the best antagonistic activity against Listeria monocytogenes,and the inhibitory zone diameter was 23.30 mm,while,the antibacterial effect was weak on Micrococcus luteus,which with an inhibitory zone diameter of 18.96 mm. This study provided a certain reference value for screening of LAB with antibacterial activity.