Genotypic and phenotypic diversity among Lactobacillus plantarum and Lactobacillus pentosus isolated from industrial scale cucumber fermentations.

The Lactobacillus plantarum and Lactobacillus pentosus genotypes existing in industrial-scale cucumber fermentations were defined using rep-PCR-(GTG)5. The ability of each genotype to ferment cucumbers under various conditions was evaluated. Rep-PCR-(GTG)5 was the technique capable of illustrating the most intraspecies discrimination compared to the sequencing of housekeeping genes (recA, dnaK, pheS and rpoA), MLST and RAPD with primers LP1, OPL5, M14 and COC. Ten genotypic clusters were defined for the 199 L. pentosus tested and three for the 17 L. plantarum clones. The ability of the 216 clones genotyped and 37 additional cucumber fermentation isolates, of the same species, to rapidly decrease the pH of cucumber juice medium under various combinations of sodium chloride (0 or 6%), initial pH (4.0 or 5.2) and temperatures (15 or 30 °C) was determined using a fractional factorial screening design. A reduced fermentation ability was observed for the L. plantarum strains as compared to L. pentosus, except for clone 3.2.8, which had a ropy phenotype and aligned to genotypic cluster A. L. pentosus strains belonging to three genotypic clusters (B, D and J) were more efficient in cucumber juice fermentation as compared to most L. plantarum strains. This research identified three genetically diverse L. pentosus strains and one L. plantarum as candidates for starter cultures for commercial cucumber fermentations.

Complete genome sequence analysis of a strain Lactobacillus pentosus ZFM94 and its probiotic characteristics.

Lactic acid bacteria have been attracting increased attentions recent years because of harboring probiotic properties. In present study, a Lactobacillus pentosus strain ZFM94 was screened from healthy infant feces and its probiotic characteristics were investigated. We found that ZFM94 was resistant to environmental stresses (temperature, pH and NaCl), tolerant to gastrointestinal juice and bile salts, with inhibitory action against pathogens and capacity of folate production etc. Additionally, complete genome sequence of the strain was analyzed to highlight the probiotic features at genetic level. Genomic characteristics along with the experimental studies is critically important for building an appropriate probiotic profile of novel strains. Genes that correspond to phenotypes mentioned above were identified. Moreover, genes potentially related to its adaptation, such as carbon metabolism and carbohydrate transporter, carbohydrate-active enzymes, and a novel gene cluster RaS-RiPPs, were also revealed. Together, ZFM94 could be considered as a potential probiotic candidate.

Probiotic Properties of Lactobacillus Strains Isolated from Table Olive Biofilms.

In this work, 16 strains with promising probiotic characteristics belonging to the Lactobacillus pentosus (13) and Lactobacillus plantarum (3) species and isolated from table olive biofilms were tested for adherence to cell lines and to solvents, immunomodulatory, and anti-proliferative properties on epithelial human cellular lines. Most Lactobacillus strains were able to regulate the production of cytokines by stimulating the production of pro-inflammatory (IL-6) and anti-inflammatory (IL-10) interleukins on macrophages, and by suppressing the secretion of IL-8 on HT-29 TNF-α-induced model. Lactobacillus strains also showed anti-proliferative activity on the HT-29 cell line. No clear relation was found between adhesion to solvents and adhesion to HT-29 human cell line. Lactobacillus pentosus LPG1, which showed the best anti-inflammatory and immunomodulatory properties, was then tested in a dinitro-benzene sulfonic acid (DNBS)-induced chronic colitis murine model. As a measure of the inflammation, gut permeability and weight loss, as well as cytokine profiles, were determined. Lactobacillus pentosus LPG1 improved mice health as observed by a significant reduction of weight loss, gut permeability, and beneficial cytokine modulation. Macroscopic scores and tissue damage were also lower in mice administered with LPG1 with respect to the DNBS-treated group. These results showed that L. pentosus LPG1 isolated from plant could have potential as probiotic for use as an anti-inflammatory and immunomodulatory agent for patients with inflammatory bowel disease.

Isolation and Characterisation of Probiotics for Antagonising the Cariogenic Bacterium Streptococcus mutans and Preventing Biofilm Formation.

PURPOSE: Consumption of refined foods and beverages high in sugar make the teeth susceptible to the formation of biofilm and may lead to dental caries. The aim of the present study was to determine the ability of selected probiotics to inhibit growth and biofilm formation by the cariogenic bacterium Streptococcus mutans in vitro. MATERIALS AND METHODS: Strains of latic acid bacteria (LAB) (n = 120) from the Bioresources Collection and Research Center (BCRC), saliva of healthy adults and infant stool were screened. The antimicrobial activity of LAB in vitro was evaluated by agar spot culture and co-culture of the S. mutans strains. Antagonistic substances in the spent culture suspensions (SCS) of LAB were precipitated by extraction with ammonium sulphate and chloroform to characterise the protein and lipophilic fractions. RESULTS: Results of co-culturing show that the SCS of the three LAB strains (Lactobacillus pentosus 13-1, 13-4 and L. crispatus BCRC 14618) subjected to heat treatment showed statistically significantly higher antimicrobial activity. Substances produced by L. pentosus 13-4 which have the potential to exhibit antimicrobial properties might be lipophilic proteins. Additionally, microtiter plate biofilm assays indicated that in vitro biofilm formation by S. mutans is strongly modulated by L. pentosus 13-4 and L. crispatus BCRC 14618. CONCLUSION: It can be inferred that the mechanism of reducing biofilm formation by these two LAB strains is associated with sucrose-dependent cell-cell adhesion and the gtfC level of glucosyltransferases in the biofilm. Therefore, it is suggested that L. pentosus 13-4 and L. crispatus BCRC 14618 may contribute to preventing dental caries, as they showed an inhibitory effect on the growth and biofilm formation of the cariogenic bacterium S. mutans in vitro.

In silico genomic insights into aspects of food safety and defense mechanisms of a potentially probiotic Lactobacillus pentosus MP-10 isolated from brines of naturally fermented Aloreña green table olives.

Lactobacillus pentosus MP-10, isolated from brines of naturally fermented Aloreña green table olives, exhibited high probiotic potential. The genome sequence of L. pentosus MP-10 is currently considered the largest genome among lactobacilli, highlighting the microorganism's ecological flexibility and adaptability. Here, we analyzed the complete genome sequence for the presence of acquired antibiotic resistance and virulence determinants to understand their defense mechanisms and explore its putative safety in food. The annotated genome sequence revealed evidence of diverse mobile genetic elements, such as prophages, transposases and transposons involved in their adaptation to brine-associated niches. In-silico analysis of L. pentosus MP-10 genome sequence identified a CRISPR (clustered regularly interspaced short palindromic repeats)/cas (CRISPR-associated protein genes) as an immune system against foreign genetic elements, which consisted of six arrays (4-12 repeats) and eleven predicted cas genes [CRISPR1 and CRISPR2 consisted of 3 (Type II-C) and 8 (Type I) genes] with high similarity to L. pentosus KCA1. Bioinformatic analyses revealed L. pentosus MP-10 to be absent of acquired antibiotic resistance genes, and most resistance genes were related to efflux mechanisms; no virulence determinants were found in the genome. This suggests that L. pentosus MP-10 could be considered safe and with high-adaptation potential, which could facilitate its application as a starter culture and probiotic in food preparations.

Molecular Detection of Two Potential Probiotic Lactobacilli Strains and Evaluation of Their Performance as Starter Adjuncts in Yogurt Production.

A molecular method for efficient and accurate detection and identification of two potential probiotic lactobacilli strains isolated from fermented olives, namely Lactobacillus pentosus B281 and Lb. plantarum B282, was developed in the present study. Random Amplified Polymorphic DNA (RAPD) analysis was performed, and strain specific primers were designed and applied in a multiplex polymerase chain reaction (PCR) assay. The specificity of the assay was tested and successfully confirmed in 27 and 22 lactobacilli strains for Lb. pentosus B281 and Lb. plantarum B282, respectively. Moreover, the two strains were used as starter cultures in yogurt production. Cell enumeration followed by multiplex PCR analysis demonstrated that the two strains were present in yogurt samples at levels ≥6 log CFU/g even after 35 days of storage at 4 °C. Microbiological analysis showed that lactobacilli and streptococci were present within usual levels, whereas enterobacteriaceae and yeast/mold counts were not detected as expected. Although the pH values of the novel products were slightly lower than the control ones, the yogurt containing the probiotic cultures scored similar values compared to the control in a series of sensory tests. Overall, these results demonstrated the possible use of the two strains as starter adjuncts in the production of yogurt with potential probiotic properties.

Sequence analysis of five endogenous plasmids isolated from Lactobacillus pentosus F03.

Lactobacillus pentosus F03, a strain isolated from pig intestines in Taiwan, contains multiple endogenous plasmids. We isolated, completely sequenced, and characterized five of the plasmids present in L. pentosus F03 designated as pF03-1 (3282bp), pF03-2 (3293bp), pF03-3 (1787bp), pF03-4 (2138bp), and pF03-5 (1949bp). The replication types of these plasmids were predicted by comparing the features of the replicon nucleotides and the similarity of replication proteins with those of the plasmids of known replication types. The results of basic local alignment search tool analyses indicate that these plasmids, except for pF03-4, belong to different replicating plasmid families. According to replicon and initiator protein analyses, pF03-1, pF03-2, and pF03-3, were determined to belong respectively to the pMV158, pC194/pUB110, and pT181 families of rolling-circle replication plasmids. However, pF03-5 contains the typical features observed in the family of theta-replicating plasmids and belongs to the pUCL287 family of theta-replicating plasmids.