Identification of Antimicrobial Substance Producing Lactic Acid Bacteria Isolate KUB-KJ174 and Its Application as a Biopreservative Substance for Bakery Products

บทคัดย่อ

The effective antimicrobial substance producing KUB-KJ174 was identified as Lactobacillus plantarum. The supernatant with a low pH of 3.6 showed 100% spectrum inhibitory activity against contaminant bacterial groups of 50 aerobic mesophiles, 10 Bacillus cereus and 53 coliform, but only 46% spectrum inhibitory activity against 13 lactic acid bacteria (LAB). However, when the pH was adjusted to 5, only low spectrum inhibitory activity against aerobic mesophilic bacteria, Bacillus cereus, coliform and LAB was shown with 26, 50, 47 and 0%, respectively. Partial purification by pH-mediated cell adsorption-desorption provided an active antimicrobial substance (the so-called PP-174) that displayed 100% growth inhibitory activity against microbial strains of aerobic mesophilic bacteria T6.14, B. cereus B6.2, coliform C4.1, LAB L2.2 and yeast Y5.1 showing low sensitivity to antimicrobial substances. However, a low concentration of 0.5% PP-174 could not inhibit the growth of LAB L2.2 within 24 h. A combination of 0.5% PP-174 with 17.42 mM lactic acid and 6.91 mM acetic acid (the socalled BAKE-SAFE-1) was able to inhibit the growth of LAB completely. Cream filling treated with BAKE-SAFE-1 completely inhibited the contaminant group of B. cereus and LAB at 15°C. When the temperature was increased to 25 and 37°C, only a low growth inhibitory efficiency of 11.68-41.45% against the contaminant group of aerobic mesophilic bacteria, B. cereus and LAB occurred. However, 100% growth inhibitory efficiency was displayed against the contaminant groups of coliform and yeast mold.