本土乳酸菌 Lactobacillus paracasei subsp. paracasei NTU 101 及 Lactobacillus plantarum NTU 102 所生產抗菌物質之純化與抗齲應用

Abstract

Lactic acid bacteria (LAB) are widely distributed in nature such as in dairy, fish as well as vegetables and grains. LAB fermented foods are less susceptible to microbial spoilage and prolong shelf life in food preservation. Previous studies showed that metabolites produced from LAB including organic acids (lactic acid, acetic acid), diacetyl, hydrogen peroxide, bacteriocins and some low molecular weight compounds have antimicrobial abilities. Among these antimicrobial metabolites, peptides or the low molecular weight compounds with bacteriostatic and bactericidal action, attracted interest of researchers and food producers for the potential to be biopreservative additives. In this study, we investigated the antimicrobial activity of supernatant of Lactobacillus paracasei subsp. paracasei NTU 101 and Lactobacillus plantarum NTU 102 and demonstrated the broad inhibitory spectrum. The antimicrobial substances were purified, characterized and identified by nuclear magnetic resonance (NMR) techniques. In animal experiments, we assessed Streptococcus mutans counts and caries scores to evaluate the decay process during a 68-day period. These agents significantly reduced oral cariogenic bacteria and caries scores (p < 0.05). The results revealed that the bacteriological factors involved in the caries process can be suppressed. These results suggested that the antimicrobial substances produced by L. paracasei subsp. paracasei NTU 101 and L. plantarum NTU 102 have protective functions against dental caries development. The production of antimicrobial substances was optimized by the Box-Behnken experimental design. An empirical model was developed through response surface methodology to describe the relationship between variables (molasses, soy-milk, and incubation temperature). The results revealed that an alternative medium could be used for large-scale commercial production of the antimicrobial substances, with potential prospects for application.