ACID PRODUCTION AND PROBIOTIC PROPERTIES OF SELECTED LACTIC ACID BACTERIA

Abstract

Thirty-six isolates of lactic acid bacteria (LAB) from tree barks were screened for lactic acid production and forty-one isolates from animal feces, healthy human feces, fermented foods, soy sauce mash and silages were screened for the probiotic properties. The selected isolates (52 isolates) were belonged to the genera Lactobacillus (12 strains), Enterococcus (14 strains), Pediococcus (7 strains), Lactococcus (1 strain), Weissella (7 strains) and Sporolactobacillus (11 strains), and they were identified as L. futasaii (2 strains), L. acidipiscis (2 strains), each strain of L. namurensis, L. farraginis, L. mucosae, L. paracasei subsp. tolerans and L. salivarius, L. pentosus (3 strains), E. hirae (10 strains), E. avium (4 strains), P. pentosaceus (4 strains), P. acidilactici (3 strains), Lc. garvieae (1 strain), W. paramesenteroides (3 strains), W. thailandensis (2 strains), W. cibaria (1 strain), W. confusa (1 strain), S. nakayamae subsp. nakayamae (3 strains), S. terrae (2 strains), S. kofuensis (1 strain) S. inulinus (3 strains) and two strains BK92T and BK117-1T isolated from White-Meranti and African Tulip tree barks were proposed as novel species as Sporolactobacillus shoreae sp.nov. and Sporolactobacillus spathodeae sp.nov., respectively based on their phenotypic, chemotaxonomic and genotypic characteristics including 16S rRNA gene sequence analysis. S. inulinus BK65-3 and BK70-3 was found to produce 101.42 g/L and 117.85 g/L of lactic acid, respectively with high optical purity of D-lactic acid (100%ee) from 120 g/L of glucose concentrations. The optimum condition of lactic acid production of S. inulinus BK65-3 was 140 g/L of glucose at 48 h without agitation and provided lactic acid of 131.45 g/L, yield of 93.89%, and productivity of 2.74 g/L.h while at same condition S. inulinus BK70-3 was required agitation and provided lactic acid of 133.79g/L, yield of 95.56% and productivity of 2.79 g/L.h. The productivity of S. inulinus BK70-3 was increased to 2.93 when cultivated in 5-L fermentor. S. inulinus BK70-3 could tolerant at high glucose concentrations up to 200 g/L. The strain S. inulinus BK70-3 could be considered as the good strain for lactic acid production. L. acidipiscis SR7-1 and L. farraginis SL4-1 showed cytotoxic effects against colorectal cancer cell lines (Caco-2 cells) with non-toxicity to normal cell lines (Vero cells). All isolates showed no cytotoxic effects against leukemic U937 cells. Fifteen strains including L. futasaii PC72-4, P. pentosaceus PC73-3, L. futasaii KC74-1, L. acidipiscis PC75-2, L. namurensis KC78-5, W. thailandensis PC79-5, W. thailandensis KC81-2, W. cibaria PC86-2, L. acidipiscis SL4-1, L. farraginis SR7-1, L. mucosae SL7-2, L. paracasei subsp. tolerans MSMC39-5, W. confusa MSMC57-2, W. paramesenteroides MSMC63-2, and L. salivarius MSMC120-2 induced IL-12 production ranged from 1,585.23 ± 7.80 to 430.65 ± 35.02pg/ml that was higher than L. plantarum NRIC 1067. All strains were tolerated in 1% bile. P. pentosaceus PC73-3, L. namurensis KC78-5, L. farraginis SL4-1 and L. mucosae SL7-2 were acid tolerated to pH 3 and showed higher adhesion ability as compared to positive control L. rhamnosus GG. Thus, P. pentosaceus PC73-3, L. namurensis KC78-5, L. farraginis SL4-1 and L. mucosae SL7-2 were the potential probiotics for prevention of cancers by stimulation of IL-12 production, especially, L. farraginis SL4-1 might be useful in colorectal cancer due to their cytotoxic effects against colorectal cancer.