Effect of Sequential Inoculum of Beta-Glucosidase Positive and Probiotic Strains on Brine Fermentation to Obtain Low Salt Sicilian Table Olives

In the present study, the β-glucosidase positive strain Lactobacillus plantarum F3. 3 was used as starter during the fermentation of Sicilian table olives (Nocellara Etnea cultivar) at two different salt concentrations (5 and 8%), in order to accelerate the debittering process. The latter was monitored through the increase of hydroxytyrosol compound. In addition, the potential probiotic Lactobacillus paracasei N24 strain was added after 60 days of fermentation. Un-inoculated brine samples at 5 and 8% of salt were used as control. The fermentation was monitored till 120 days through physico-chemical and microbiological analyses. In addition, volatile organic compounds and sensorial analyses were performed during the process and at the end of the fermentation, respectively. Lactic acid bacteria and yeasts were, in depth, studied by molecular methods and the occurrence of the potential probiotic N24 strain in the final products was determined. Results highlighted that inoculated brines exhibited a higher acidification and debittering rate than control ones. In addition, inoculated brines at 5% of salt exhibited higher polyphenols (hydoxytyrosol, tyrosol, and verbascoside) content compared to samples at 8% of NaCl, suggesting a stronger oleuropeinolytic activity of the starter at low salt concentration. Lactobacilli and yeasts dominated during the fermentation process, with the highest occurrence of L. plantarum and Wickerhamomyces anomalus, respectively. Moreover, the potential probiotic L. paracasei N24 strain was able to survive in the final product. Hence, the sequential inoculum of beta-glucosidase positive and potential probiotic strains could be proposed as a suitable technology to produce low salt Sicilian table olives.

Metagenetic and Volatilomic Approaches to Elucidate the Effect of Lactiplantibacillus plantarum Starter Cultures on Sicilian Table Olives

The present study aimed to evaluate the effect of selected Lactiplantibacillus plantarum strains on both microbiota composition and volatile organic compound profile of Sicilian table olives. Two mixed cultures, named O1 and O2, were set up for pilot-plan scale fermentations at 5% of NaCl. Uninoculated table olives at 5 and 8% (C5 and C8) of salt were used as control. The fermentation process was monitored until 80 days through a dual approach, which included both classical microbiological and 16S amplicon-based sequencing and volatilomics analyses. Compared with control samples (C5 and C8), experimental samples, inoculated with starter cultures (O1 and O2), exhibited a faster acidification with a more pronounced drop in pH. Metagenetics data revealed significant differences of microbiota composition among samples, highlighting the dominance of lactobacilli in both experimental samples; a high occurrence of Enterobacter genus only in control samples with 5% of NaCl; and the presence of Bacteroides, Faecalibacterium, Klebsiella, and Raoultella genera only in control samples with 8% of NaCl. Furthermore, microbiota composition dynamics, through the fermentation process, significantly affected the volatile organic compounds of the final products, whereas no compounds involved in off-odors metabolites were detected in all samples investigated. In conclusion, the addition of the proposed starter cultures and the use of low concentrations of sodium chloride positively affected the microbiota and volatile organic compounds, ensuring the microbiological safety and the pleasant flavors of the final product.

Characterization of Bifidobacterium asteroides Isolates

Bifidobacteria have long been recognized as bacteria with probiotic and therapeutic features. The aim of this work is to characterize the Bifidobacterium asteroides BA15 and BA17 strains, isolated from honeybee gut, to evaluate its safety for human use. An in-depth assessment was carried out on safety properties (antibiotic resistance profiling, β-hemolytic, DNase and gelatinase activities and virulence factor presence) and other properties (antimicrobial activity, auto-aggregation, co-aggregation and hydrophobicity). Based on phenotypic and genotypic characterization, both strains satisfied all the safety requirements. More specifically, genome analysis showed the absence of genes encoding for glycopeptide (vanA, vanB, vanC-1, vanC-2, vanD, vanE, vanG), resistance to tetracycline (tetM, tetL and tetO) and virulence genes (asa1, gelE, cylA, esp, hyl).

Characterization of Cell-Envelope Proteinases from Two Lacticaseibacillus casei Strains Isolated from Parmigiano Reggiano Cheese

In the present work, two cell-envelope proteinases (CEPs) from Lacticaseibacillus casei strains PRA205 and 2006 were characterized at both the biochemical and genetic levels. The genomes of both L. casei strains included two putative CEPs genes prtP2 and prtR1, but only prtR1 was transcribed. The extracted PrtR1 proteinases were serine proteinases with optimal activity at 40 °C and pH 7.5, and were activated by Ca²⁺ ions. Interestingly, PrtR1 from L. casei PRA205 exhibited high residual activity at pH 4 and at 5 °C, suggesting its possible exploitation for fermented food production. The caseinolytic activity against αS1- and β-casein indicated that both PrtR1s belonged to the PI/PIII type. These PrtR1s cleaved β-casein peptide bonds preferentially when amino acid M or N was present at the P1 subsite and amino acids A and D were at the P1' subsite. Several bioactive peptides were found to be released from PrtR1 after αs1- and β-casein hydrolysis.

Adhesion Properties and Pathogen Inhibition of Vaginal-Derived Lactobacilli

In the present study, twenty-seven (27) lactobacilli strains, isolated from the vagina of healthy Italian women of reproductive age, were screened for probiotic properties. The strains were evaluated for antagonistic activity against pathogens, adhesion abilities, and potential to displace and/or inhibit the adhesion of previously adhered pathogens as a primary strain selection criterion. Overall, all the tested lactobacilli inhibited at least three pathogens, and the majority of them exhibited antimicrobial activity against Enterobacter cloacae DSM 30054, Pseudomonas aeruginosa DSM 3227, and Pseudomonas aeruginosa DSM 1117. The complete neutralization of antimicrobial activity after cell-free supernatant (CFS) neutralization suggested a pivotal role for lactic acid or other organic acids secreted by the lactobacilli. The strains showed variability in their adhesion levels, but all tested strains adhered to both human colonic epithelial cells (HT-29) and vaginal cells (VK2/E6E7) with adhesion percentages exceeding 1%. The ability to displace or inhibit pathogens was dependent on the pathogen and the lactobacilli strain; the pathogen displacement levels ranged from 9 to 82%, while pathogen exclusion levels varied from 1 to 99%. In conclusion, this study demonstrates the protective effect of vaginal lactobacilli against pathogens and confirms the suitability of the vaginal microbiota as a source of potential probiotic strains. The selected lactobacilli hold promise for the formulation of supplements to enhance genitourinary tract health.

Lacticaseibacillus rhamnosus TOM 22.8 (DSM 33500) is an effective strategy for managing vaginal dysbiosis, rising the lactobacilli population

AIM

The present study is a single-centre, randomized, controlled clinical trial aimed to evaluate the effectiveness of the probiotic Lacticaseibacillus rhamnosus TOM 22.8 (DSM 33500) strain, orally administrated, to treat vaginal dysbiosis.

METHODS AND RESULTS

Overall, 80 women, with signs and symptoms of vaginal dysbiosis, were enrolled and allocated to the treatment group (A, n=60), who took 1 capsule of the probiotic strain for 10 consecutive days, or the non-treatment group (B, n=20), who did not receive any treatment. Clinical (vaginal signs and symptoms; pH of the vaginal fluid; Amsel criteria; Nugent score; Lactobacillary grade) and microbiological examinations were performed at baseline (T0), 10 days (T1), and 30 (T2) days after the oral administration of the probiotic TOM 22.8 strain. The latter resulted in a restoration of the physiological pH, accompanied by remission or attenuation of clinical signs and symptoms as well as the improvement of the quality of life (QoL). Microbiological data revealed a significant reduction of potentially pathogenic bacteria.

CONCLUSION

The administration of the L. rhamnosus TOM 22.8 probiotic strain could be proposed as an effective strategy for the treatment of vaginal dysbiosis.

Oral Intake of the Commercial Probiotic Blend Synbio® for the Management of Vaginal Dysbiosis

A healthy vaginal microbiota is Lactobacillus-dominated. Several factors can interfere with the state of balance leading to dysbiosis, such as vaginal infections caused by bacteria and Candida species. The present single-arm, uncontrolled open-label study aimed to evaluate the ability of the SYNBIO^® probiotic combination, taken as an oral formulation, to contribute to vaginal health. Thirty pre-menopausal participants were included in the study. Participants were instructed for daily oral intake of SYNBIO^® probiotic capsules for 15 days. Vaginal swabs were collected at baseline (T0), 15 days after the start of the treatment (T1), and 7 days after the end of the treatment (T2). Amsel criteria, Nugent score, and vaginal pH were evaluated at each sampling time. In addition, the participants' quality of life was assessed by the WHOQOL-BREF questionnaire. The administration of SYNBIO^® once daily for 15 days resulted in a substantial improvement in the vaginal flora in terms of an increase in lactobacilli and a decrease in enterococci, staphylococci, Gardnerella spp., and Candida spp. According to the results, statistically significant changes in leucorrhoea, itching, and vulvo-vaginal erythema/edema as well as a decrease in all the Amsel criteria were recorded. The oral consumption of SYNBIO^® demonstrated enhanced benefits for vaginal health.

Genome Mining and Characterization of Two Novel Lacticaseibacillus rhamnosus Probiotic Candidates with Bile Salt Hydrolase Activity

Bile salt hydrolase (BSH; EC 3.5.1.24) is the microbial enzyme that catalyzes the conversion of primary bile acids (BAs) into secondary ones, promoting microbial adaptation and modulating several host's biological functions. Probiotics with BSH activity are supposed to survive harsh intestinal conditions and exert a cholesterol-lowering effect. Here, Lacticaseibacillus rhamnosus strains (VB4 and VB1), isolated from the vaginal ecosystem, were submitted to a genomic survey, in vitro BSH activity, and BAs tolerance assay to unravel their probiotic potential as BAs modulators. The draft genomes of Lcb. rhamnosus VB4 and VB1 strains comprised 2769 and 2704 CDSs, respectively. Gene annotation revealed numerous strain-specific genes involved in metabolism and transport, as well as in DNA recombination. Each strain harbors a single bsh gene, encoding a C-N amide hydrolase, which conserved the essential residues required in the BSH core site. According to the results, compared to VB1, the VB4 strain tolerated better BAs stress and was more active in deconjugating BAs. However, BAs stress increased the bsh gene transcription in the VB1 strain but not in the VB4 strain, suggesting a partially nonlinear relationship between BSH activity and gene expression. In conclusion, despite the complexity of the BSH transcriptional system, the results support the VB4 strain as a promising BAs-deconjugating probiotic candidate.

Quantitative PCR Assay as a Tool for the Detection of Lactobacilli in Sicilian Table Olives Produced at an Industrial Scale

Table olives are an important fermented product of the Mediterranean area consumed all over the world. In our era, the food industry requires a safe and stable final product with desirable characteristics for the consumer. In the present study, two different experimental fermentations (L, with Lactiplantibacillus plantarum strains, and LY, with L. plantarum strains and Wickerhamomyces anomalus strain) were conducted and monitored up to 180 days and compared with a spontaneous fermentation, used as control (C). The safety and stability of table olives were determined by applying a plate count and quantitative real-time PCR (qPCR) approach. Compared with the control sample (C), experimental fermentations showed a faster acidification and a good inhibition rate of spoilage bacteria, indicating the safety of the process. Quantitative PCR data confirmed the abundance of the Lactobacillus group in both experimental table olives, confirming the importance of the starter cultures for the stability of the final product. In conclusion, the use of starter cultures ensures the safety of industrially produced table olives, and the application of qPCR seems to be a promising tool to detect and quantify lactobacilli as a positive biomarker of table olive fermentation.