Abstract:
Seventy lactic acid bacteria (LAB) were isolated from flowers (17 strains), 3 tree barks (7 strains), one fruit (2 strains), ten fermented tea leaves (31 strains) and two silage (13 strains). They were identified as Lactobacillus pentosus (12 strains), L. plantarum subsp. plantarum (9 strains), L. paracasei subsp. tolerans (5 strains), L. brevis (1 strain), L. silagincola (1 strain), L. kunkeei (1 strain), and L. formosensis (1 strain), Enterococcus durans (3 strains), E. lactis (2 strains), E. faecalis (1 strain), E. faecium (1 strain), E. gallinarum (1 strain) and E. gilvus (1 strain), Pediococcus acidilactici (1 strain) and P. pentosaceus (1 strain), and Aerococcus urinaeequi (1 strain) based on their phenotypic characteristics and 16S rRNA gene sequences. Strain FM11-1T, a novel species isolated from the flower of Solanum torvum, was closely related to E. faecium NRIC 1145T (98.79 %), E. durans NBRC 100479T (98.72 %), E. lactis LMG 25958T (98.49 %), and E. ratti DSM 15687T (98.02 %) based on the 16S rRNA gene sequence, genome sequence, and phylogenetic tree. Therefore, it was proposed as Enterococcus solani sp. nov. The screening of bile salt hydrolase, cholesterol assimilation, antimicrobial activity, and cytotoxicity against Caco-2 cells revealed that 28 strains showed bile salt hydrolase activity while 19 strains exhibited cholesterol assimilation more than 45 %. Strain CRM44-2 showed the highest cholesterol assimilation of 85.5 %. Furthermore, the strains FM3-1, FM11-1, FM11-2, CM28-3, CM38-1, CRM41-1, CRM55-2, and NWM60-2 exhibited bile salt hydrolase activity and cholesterol assimilation more than 45 %. Strain CRM51-2 showed antimicrobial activity against Bacillus subtilis ATCC 6633. Strains CM28-3 and CRM42-1 showed cytotoxic effects against colorectal cancer cell lines (Caco-2 cells) with non-toxicity to Vero cells. All isolates showed no cytotoxic effects against Vero and HepG2 cells. For the probiotic properties, 31 strains showed pH 3.0 and 0.3 % of bile acid tolerance for 3 hours by decreasing 2 log cycles while 13 strains showed the adhesion ability. L. brevis strain CM38-1 isolated from fermented tea leaves, showed bile salt hydrolase activity, cholesterol assimilation of 62.5 % and adhesion ability of 6.0 + 1.0 % as the candidate probiotics with cholesterol-lowering. Moreover, L. plantarum subsp. plantarum strain CM28-3 isolated from fermented tea leaves, showed bile salt hydrolase activity, cholesterol assimilation of 46.5 %, cytotoxicity against Caco-2 cells of 64.0 + 0.1 %, and adhesion ability of 0.7 + 1.0 %. Therefore, it is suggested to be the candidate probiotics with higher cholesterol-lowering activity compared to L. rhamnosus GG as positive control.