Cholesterol-lowering and probiotic properties of selected lactic acid bacteria

Abstract

Ninety strains of lactic acid bacteria (LAB) isolated from fermented foods and bark of Tamarindus indica were screening cholesterol-lowering effects, selected and identified based on the phenotypic, chemotaxonomic characteristics and 16S rRNA gene sequence analysis. They were identified as Companilactobacillus farciminis (5 strains), C. formosensis (10 strains), C. futsaii (6 strains), C. pabuli (4 strains), Enterococcus thailandicus (2 strains), Lactiplantibacillus argentoratensis (3 strains), Lactiplantibacillus pentosus (10 strains), Lactiplantibacillus plantarum subsp. plantarum (17 strains), Lactococcus lactis subsp. lactis (2 strains), Lentilactobacillus buchneri (8 strains), Limosilactobacillus fermentum (2 strains), P. pentosaceus (12 strains) and each of En. durans, En. hirae, En. lactis, Lacticaseibacillus paracasei subsp. tolerans, Lacticaseibacillus rhamnosus, Lactococcus lactis subsp. hordniae, Leuconostoc lactis and Pediococcus acidilactici. Strain BCM23-1T isolated from bark of Tamarindus indica was closely related to Terrilactibacillus laevilacticus NK26-11T (98.3 %). The draft genome of BCM23-1T was 3.24 Mb in size and contained 3088 coding sequences with an in silico DNA G+C content of 37.1 mol%. The values of ANIb, ANIm and digital DNA–DNA hybridization between strain BCM23-1T and T. laevilacticus NK26-11T were 89.9, 90.8 and 40.4 %, respectively. The results of phenotypic and chemotaxonomic, 16S rRNA gene sequence similarity, phylogenetic tree analysis and whole genome analyses support strain BCM23-1T as representing a novel species of Terrilactibacillus for which the name Terrilactibacillus tamarindi sp. nov. is proposed. Twelve selected strains exhibited bile salt hydrolase activity (BSH activity) and the ability of cholesterol assimilation. Strain L. plantarum LM14-2 showed the greatest cholesterol assimilation ability at 86.07%. From the investigation of fundamental probiotic properties, twelve selected strains could tolerate and survive in the simulated gastric condition for 3 hours and simulated small intestinal condition for 5 hours, and adhere to Caco-2 cells at 82.46 to 31.16%. In addition, all selected strains were evaluated other health-promoting effects. All selected strains showed immunomodulatory effects. Furthermore, only Lc. lactis subsp. lactis NH2-7C could synthesis bacteriocin containing anti-pathogenic activity. Based on the genomic data, bacteriocin NH2-7C was identified as nisin A. The bacteriocin NH2-7C was partially purified through hydrophobic interaction and cation exchange chromatography and characterized. The partially purified bacteriocin NH2-7C was stable at 100 ⸰C for 30 minutes and it showed antimicrobial activity at pH 2 to 7. The partially purified bacteriocin NH2-7C was sensitive to protease-K. Based on the genomic analysis, L. plantarum LM14-2 and Lc. lactis subsp. lactis NH2-7C were safe and they were predicted as non-human pathogen and contained probiogenomic characteristics.