식품미생물 유래 천연항균소재의 식중독균 생육저해 효과와 이의 식품적용

Abstract

Lactobacillus plantarum AF1, Lb. plantarum HD1, Lb. plantarum EM and Bacillus subtilis SN7 were isolated from Kimchi and Meju. Growth inhibitory effects of lactic acid bacteria and Bacillus subtilis producing antimicrobial compounds on food pathogens were investigated using co-cultivation technique; growth of the pathogenic molds and bacteria were completely inhibited within 12∼36 hr, whereas growth of yeast was completely inhibited after 48 hr of incubation by treatment of LAB. Reduction of E. coli O157:H7 cell growth (2 log CFU/mL) was observed at 24 hr by treatment of B. subtilis. However, growth of LAB and B. subtilis were not affected by co-cultivation with the pathogens. When hyphae and spores of molds were treated with culture supernatant of the LAB, the growth of hyphae and germination of spores were inhibited. Growth of the pathogenic bacteria was completely inhibited within 4 hr and reduction of yeast cell growth (2 log CFU/mL) was observed at 48 hr by treatment of the LAB culture supernatant. When E. coli O157:H7 was treated with B. subtilis culture supernatant, cell growth of the E. coli O157:H7 was not inhibited. After the hyphae and spores were treated with the LAB supernatant, they were inoculated into the culture medium (MEB), and then their growth was observed. None of growth of hyphae or spore was observed after this treatment. When the molds and bacteria were treated with the LAB supernatant, outer cell wall of the mold was shrinked or damaged and cytoplasmic space was empty. Moreover, deformation of cell shape and empty hole in cytoplasmic space from the treated bacteria were observed by SEM and TEM observation. To investigate inhibitory effect of antimicrobial substance on E.coli O157:H7, salad was prepared using mix of Lb. plantarum AF1 and B. subtilis SN7 culture supernatant and additionally inoculation of E. coli O157:H7 with 1∼2 log CFU/g. Salads were stored at 37℃, 15℃, and 4℃ for 1 day, 2 days, and 3 days, respectively. As a result, when the antimicrobials were mixed and stored at 4°C for 3 days, the growth inhibition of E. coli O157:H7 was the largest. This study suggested an alternative to chemical preservatives such as natural food preservative derived from GRAS microorganisms.