In-Vitro Characterization of Growth Inhibition against the Gut Pathogen of Potentially Probiotic Lactic Acid Bacteria Strains Isolated from Fermented Products

Abstract

Lactic acid bacteria (LAB) are probiotic candidates that may restore the balance of microbiota populations in intestinal microbial ecosystems by controlling pathogens and thereby promoting host health. The goal of this study was to isolate potential probiotic LAB strains and characterize their antimicrobial abilities against pathogens in intestinal microbiota. Among 54 LAB strains isolated from fermented products, five LAB strains (NSMJ15, NSMJ16, NSMJ23, NSMJ42, and NFFJ04) were selected as potential probiotic candidates based on in vitro assays of acid and bile salt tolerance, cell surface hydrophobicity, adhesion to the intestinal epithelium, and antagonistic activity. Phylogenetic analysis based on 16S rRNA genes showed that they have high similarities of 99.58–100% to Lacticaseibacillus paracasei strains NSMJ15 and NFFJ04, Lentilactobacillus parabuchneri NSMJ16, Levilactobacillus brevis NSMJ23, and Schleiferilactobacillus harbinensis NSMJ42. To characterize their antimicrobial abilities against pathogens in intestinal microbiota, the impact of cell-free supernatant (CFS) treatment in 10% (v/v) fecal suspensions prepared using pooled cattle feces was investigated using in vitro batch cultures. Bacterial community analysis using rRNA amplicon sequencing for control and CFS-treated fecal samples at 8 and 16 h incubation showed the compositional change after CFS treatment for all five LAB strains. The changed compositions were similar among them, but there were few variable increases or decreases in some bacterial groups. Interestingly, as major genera that could exhibit pathogenicity and antibiotic resistance, the members of Bacillus, Escherichia, Leclercia, Morganella, and Vagococcus were decreased at 16 h in all CFS-treated samples. Species-level classification suggested that the five LAB strains are antagonistic to gut pathogens. This study showed the probiotic potential of the five selected LAB strains; in particular, their antimicrobial properties against pathogens present in the intestinal microbiota. These strains would therefore seem to play an important role in modulating the intestinal microbiome of the host.

Optimizing Conditions in the Acid Tolerance Test for Potential Probiotics Using Response Surface Methodology

“…As a result, the number of LGG bacteria was decreased slightly to 5.86 ± 0.45 log CFU/mL at 90 min and 5.06 ± 0.12 log CFU/mL at 180 min of exposure compared to that of the control (6.22 ± 0.05 log CFU/mL). Contrastingly, in the study by Jung et al ( 10 ), exposure of the same strain to pH 2.5 medium without pepsin for 2 h showed a remarkable decrease in the number of the cells (7.00 ± 0.67 log CFU/mL) compared to that of the control (9.79 ± 0.20 log CFU/mL). Thus, the method for conducting acid tolerance tests must be standardized and optimized to enhance the accuracy of the test.…”

The Modulatory Effects of Lacticaseibacillus paracasei Strain NSMJ56 on Gut Immunity and Microbiome in Early-Age Broiler Chickens

“…Lacticaseibacillus paracasei NSMJ56 was selected for use in this study based on its high acid tolerance identified in a previous study [ 16 ]. L .…”

Complete Genome Sequence of Lacticaseibacillus paracasei Strain NSMJ15

“…Lactic acid bacteria (LAB) are a major group of probiotic microorganisms in both humans and animals and are being extensively investigated in studies on probiotics ( 1 – 4 ). Lacticaseibacillus paracasei (formerly “ Lactobacillus paracasei ”) strain NSMJ15 was isolated from makgeolli, a traditional Korean fermented liquor, and in vitro study showed its probiotic potential, in particular, its antimicrobial properties against gut pathogens ( 5 ). Here, we report the complete genome sequence of strain NSMJ15, which supports its characteristics as a potential probiotic candidate.…”

“…Strain NSMJ15 was first isolated by serial dilutions of a makgeolli suspension and plating onto MRS agar (Difco, USA) ( 5 ). For whole-genome sequencing, genomic DNA (gDNA) was extracted from strain NSMJ15 grown in MRS broth (Difco) at 30°C for 48 h using a Maxwell 16 DNA purification kit (Promega, USA).…”