ANTIMICROBIAL ACTIVITY OF INTESTINAL MICROORGANISMS DERIVED FROM PROTAETIA BREVITARSIS SEULENSIS LARVAE

This study was done to analyze the antimicrobial activity of gut-derived microbes of Protaetiabrevitarsisseulensis larvae. Among the lactic acid bacterial strains isolated from the intestinal microbes of P. brevitarsisseulensis larvae, 10 strains were firstly selected from results of antimicrobial activity against Salmonella Typhimurium χ3339 strain as a susceptible strain. As a result, since the Minimum Inhibitory Concentration (MIC) was the best result in the K9 strain, further tests were performed on the K9 strain in subsequent studies. The K9 strain was identified as Lactobacillus plantarum from 16 SrDNA sequencing, named as L. plantarum K9. The antibacterial activity according to the amount of susceptible strain showed no or lower activity at 108 and 107 CFU/ml, whereas stronger antibacterial activity below 106 CFU/ml. The antibacterial activity test according to the cultural temperature showed the strongest antibacterial activity at 37℃. In the thermal stability test, it was confirmed that the antimicrobial activity was maintained up to 50℃ but significantly decreased from 60℃ or higher. However, some of the AMPs exhibited thermal stability because of remaining the activity above 60℃ or higher. Since proteinase K treatmentdecreases the antibacterial activity, we confirm that antibacterial activity is done by peptide-based bioactive substances. In summary, we suggest that AMPs in L. plantarum K9 strain are a potential of application as a natural antibacterial agent owing to thermal stability.