关键词: 副干酪乳杆菌, 抗菌物质, 特性

Abstract: To isolate Lactobacillus with great application potential from traditional homemade dairy products in Inner Mongolia, eight strains of Lactobacillus were screened for their antimicrobial activity. Strain Q-1-4 was found to have a broad spectrum of antimicrobial activity and was identified as Lactobacillus paracasei by physiological and biochemical characterization and 16S rDNA sequencing analysis. The antimicrobial activity of the cell-free culture supernatant (CFS) of L. paracasei Q-1-4 against Salmonella typhimurium CMCC50115 still existed after eliminating the interference factors such as lactic acid, acetic acid, and hydrogen peroxides. However, the CFS of L. paracasei Q-1-4 was inactivated after treatment with proteolytic enzymes. Inhibitory activity of the CFS against S. typhimurium CMCC50115 was observed in the pH range from 2.0 to 5.5. The antimicrobial substance had good thermal stability in this pH range and was not sensitive to ultraviolet. SDS and EDTA could enhance the antimicrobial activity, but surfactants, organic solvents and metal ions had no effect on the antimicrobial activity. In addition, the antibacterial activity had good storage stability with a broad inhibitory spectrum.

Key words: Lactobacillus paracasei, antimicrobial activity, characteristics