Characterization of an inositol-producing Lactobacillus plantarum strain and the assessment of its probiotic potential and antibacterial activity

Probiotic properties and antimicrobial evaluation of silymarin-enriched Lactobacillus bacteria isolated from traditional curd

Nowadays, the increasing use of medicinal plants in the treatment and prevention of diseases has attracted the attention of researchers. The aim of this work was to investigate the probiotic properties and antibacterial and antifungal activity of silymarin-enriched Lactobacillus bacteria against several important pathogenic bacteria and also Aspergillus flavus as one of the harmful molds in the food and health industries. For this purpose, 52 g-positive and catalase-negative bacteria were isolated from 60 traditional curd samples from Ilam province. Five of the 52 bacterial strains had more than 90% viability in high bile salt and acidic conditions and were selected for further investigation. The five strains with positive results showed good hydrophobicity (≥ 50.30%), auto-aggregation (≥ 53.70%), coaggregation (≥ 28.20%), and high cholesterol removal ability (from 09.20 to 67.20%) and therefore can be considered potential probiotics. The tested strains displayed acceptable antibacterial and antifungal activity against all 12 pathogenic bacteria and A. flavus. Also, the results of the simultaneous antifungal activity of probiotic strains and silymarin showed that the combination of silymarin and probiotics has a significantly better (P < 0.05) antifungal effect than the control group or the probiotic groups alone. Interestingly, in addition to the Limosilactobacillus fermentum C3 strain, the Limosilactobacillus fermentum C18 and Lactiplantibacillus pentosus C20 strains also had significant inhibitory effects against A. flavus when used with silymarin extract in methanol. Meanwhile, silymarin extract in DMSO and PEG increased the antagonistic activity of all five potential probiotic strains.

Integrated genome-based assessment of safety and probiotic characteristics of Lactiplantibacillus plantarum PMO 08 isolated from kimchi

Lactiplantibacillus plantarum PMO 08 has been used as a probiotic starter culture for plant-based fermented beverages, with various health-promoting effects such as cholesterol-lowering and anti-inflammatory activities. This study aimed to analyze the genome sequence of Lp. plantarum PMO 08 and identify its safety and probiotic characteristics at the genomic level. For this, complete genome sequencing was conducted to investigate the genes associated with risk and probiotic characteristics by using Pacbio combined with Illumina HiSeq. This bacterial strain has one circular chromosome of 3,247,789 bp with 44.5% G + C content and two plasmids of 50,296 bp with 39.0% G + C content and 19,592 bp with 40.5% G + C content. Orthologous average nucleotide identity analysis showed that PMO 08 belongs to the Lp. plantarum group with 99.14% similarity to Lp. plantarum WCFS1. No deleterious genes were determined in the virulence factor analysis, and no hemolysin activity or secondary bile salt synthesis were detected in vitro test. In the case of antibiotic resistance analysis, PMO 08 was resistant to ampicillin in vitro test, but these genes were not transferable. In addition, the strain showed same carbohydrate utilization with Lp. plantarum WCFS1, except for mannopyranoside, which only our strain can metabolize. The strain also harbors a gene for inositol monophosphatase family protein related with phytate hydrolysis and have several genes for metabolizing various carbohydrate which were rich in plant environment. Furthermore, in probiotic characteristics several genes involved in phenotypes such as acid/bile tolerance, adhesion ability, and oxidative stress response were detected in genome analysis. This study demonstrates that Lp. plantarum PMO 08 harbors several probiotic-related genes (with no deleterious genes) and is a suitable probiotic starter for plant-based fermentation.

Evaluation of probiotic potential of autochthonous lactobacilli strains isolated from Zabuli yellow kashk, an Iranian dairy product

AIMS

The aim of this study was evaluating the probiotic potential and anti-biofilm activity of five lactobacilli strains which isolated and identified from an Iranian product.

METHODS AND RESULTS

Five lactobacilli strains which were isolated from Zabuli yellow kashk, were evaluated for the presence of probiotic properties, such as resistance to low pH, resistance to simulated gastrointestinal conditions, bile salt tolerance, hydrophobicity, auto- and co-aggregation. In addition, antimicrobial susceptibility, adherence to Caco-2 cells (human colon cancer cell line), anti-adhesion activity, ability against biofilm formation, and biofilm degradation of mentioned strains against Pseudomonas aeruginosa PTCC 1707 were assessed. All the strains tested showed acceptable characteristics, but Lactiplantibacillus plantarum TW57-4 appeared of particular interest. Some probiotic properties of this strain were similar and in some cases higher than the commercial probiotic strain Lacticaseibacillus rhamnosus GG (standard sample). Cholesterol assimilation and radical-scavenging activity of Lpb. plantarum TW57-4 were70.2 % and 62.3 %, respectively. The adhesion degree of Lpb. plantarum TW57-4 was 10.6 %. Applying competition and inhibition assay, this strain showed 55.3 % and 62.3 % of competition and inhibition activity in adhesion of P. aeruginosa PTCC 1707 to the intestinal cells, respectively.

CONCLUSIONS

According to the obtained results, it can be concluded that Lpb. plantarum TW57-4 strain can be used as a promising candidate for in-vivo studies with the aim of developing new probiotic starter cultures.

SIGNIFICANCE AND IMPACT OF STUDY

The present study furthers our understanding of lactobacilli strains behavior after consumption to establish their beneficial effects.