Isolation and characterization of probiotic lactobacillus spp. with anti - pathogenic and anti-inflammatory activities

Abstract

Lactobacillus species have beneficial effects as probiotics. In this study, they were isolated from feces of healthy human volunteers to investigate for their two main probiotic properties: inhibition of gastrointestinal pathogens and modulation of tumor necrosis factor-α (TNF-α) productions as well as characterization of selected strains. Five hundreds and ten Lactobacillus isolates were tested for antagonistic activity against ten gastrointestinal pathogens. The results demonstrated that 4 isolates displayed weak inhibitory activities against Vibrio cholerae non O1 by agar well diffusion assay. The weak inhibitory activities were observed in 114 of 437 isolates toward Vibrio cholerae and 32 of 114 isolates toward Salmonella enterica by agar spot method. Forty-six isolates were randomly selected and investigated for the modulation of TNF-α production in THP-1 monocytic cells activated with lipopolysaccharide (LPS). The result revealed that 12 isolates significantly inhibited TNF-α production in varying degrees. Strain TH58 displayed the most potent TNF-α inhibitory activity by 70-80%. However, this strain had no effect on nuclear factor kappa B (NF- kB) activation. On the basis of phenotypic and genotypic characteristic including API 50 CHL, 16S rRNA gene sequencing, pyrosequencing and rep-PCR genotyping, 4 anti-pathogenic strains were identified as Lactobacillus plantarum. Out of 12 TNF-α inhibitory strains, 10 were identified as Lactobacillus plantarum, one as Lactobacillus salivarius and TH58 strain as Lactobacillus saerimneri. Phylogenetic relationships demonstrated Lactobacillus saerimneri distinguish from Lactobacillus plantarum and Lactobacillus salivarius which displayed 60-78% similarity by rep-PCR. It is interesting to note that Lactobacillus TH58 strain with the most potent TNF-α inhibitory activity was identified as Lactobacillus saerimneri which has never been reported as the isolate from human origin and exhibited TNF-α inhibitory activity.