Comparative Study on Growth and Metabolomic Profiles of Six Lactobacilli Strains by Sodium Selenite.

Selenium (Se) has garnered increasing attention in the field of nutrition, as it is essential for both humans and animals. Certain microorganisms can enrich inorganic selenium and convert it into organic selenium. The growth and metabolomic profiles of six lactobacilli strains exposed to 50 µg/mL of sodium selenite were performed using gas chromatography tandem time-off light mass spectrometry (GC-TOF-MS) analysis. The addition of selenium significantly increased both the population and weight of the Lacticaseibacillus rhamnosus PS5, Lbs. rhamnosus RT-B, Limosilactobacillus reuteri 3630, and Lmb. reuteri 1663 strains, while those of the other two strains decreased. A total of 271 metabolites were determined, with their concentrations ranked from highest to lowest as follows: organic acids and derivatives, oxygen compounds, lipids and lipid-like molecules, and benzenoids. In certain groups, the concentrations of serine, aspartic acid, trehalose, palmitic acid, methylthreonine, and melibiose increased significantly, whereas glucuronic acid, ribose, ornithine, and methionine were downregulated. The metabolic pathways were significantly associated with ABC transporters, glycine, serine, threonine metabolism, and aminobenzoate degradation and other pathways. Based on these findings, we concluded that the transport, absorption, assimilation, and stress response to selenium by lactobacilli in metabolomic changed. Furthermore, the metabolomic alterations among different types of lactobacilli varied primarily due to their distinct properties.

Characterization, High-Density Fermentation, and the Production of a Directed Vat Set Starter of Lactobacilli Used in the Food Industry: A Review.

Lactobacilli have been widely concerned for decades. Bacteria of the genus Lactobacillus have been commonly employed in fermented food to improve the appearance, smell, and taste of food or prolong its shelf-life. They comprise 261 species (by March 2020) that are highly diverse at the phenotypic, ecological, and genotypic levels. Some Lactobacilli strains have been documented to be essential probiotics, which are defined as a group of living microorganisms that are beneficial to the health of the host when ingested in sufficiency. However, the characterization, high-density fermentation, and the production of a directed vat set (DVS) starter of Lactobacilli strains used in the food industry have not been systematically reported. This paper mainly focuses on reviewing Lactobacilli as functional starter cultures in the food industry, including different molecular techniques for identification at the species and strain levels, methods for evaluating Lactobacilli properties, enhancing their performance and improving the cell density of Lactobacilli, and the production techniques of DVS starter of Lactobacilli strains. Moreover, this review further discussed the existing problems and future development prospects of Lactobacilli in the food industry. The viability and stability of Lactobacilli in the food industry and gastrointestinal environment are critical challenges at the industrial scale. The new production equipment and technology of DVS starter of Lactobacilli strains will have the potential for large-scale application, for example, developing low-temperature spray drying, freezing granulation drying, and spray freeze-drying.

Lactobacilli Strain Mixture Alleviates Bacterial Vaginosis through Antibacterial and Antagonistic Activity in Gardnerella vaginalis-Infected C57BL/6 Mice.

The present study investigated the anti-bacterial vaginitis (BV) effects of a mixture of five lactobacilli strains (LM5), containing equal amounts of Ligilactobacillus salivarius MG242, Limosilactobacillus fermentum MG901, Lactiplantibacillus plantarum MG989, Lacticaseibacillus paracasei MG4272, and Lacticaseibacillus rhamnosus MG4288), in HeLa cells and Gardnerella vaginalis (GV)-infected BV mice. All strains produced lactic acid and hydrogen peroxide, and were resistant to nonoxynol-9. LM5 significantly inhibited GV growth by 80%, exhibited good adhesion to HeLa cells, and significantly inhibited GV adhesion to these cells. In GV-infected mice, LM5 administered orally at 5 × 109 CFU/mouse significantly inhibited GV proliferation in the vaginal tract and significantly reduced myeloperoxidase activity, pro-inflammatory cytokine (TNF-α, IL-1ß, and IL-6) levels, and nitric oxide levels in vaginal tissue lysates. Histopathological analysis of vaginal tissues revealed that LM5 markedly suppressed the exfoliation of vaginal epithelial cells. Overall, these results suggest that LM5 might alleviate BV by direct antibacterial and antagonistic activity in vaginal tissues of GV-infected mice.

Screening of autochthonous vaginal beneficial lactobacilli strains by their growth at high temperatures for technological applications.

The pharmaceutical industry shows an emerging interest in formulas that contain live and beneficial microorganisms, also known as probiotics or pharmabiotics, which in many cases, are host-specific. The resistance to higher temperature is an essential feature of these microorganisms when working on the design of products for vaginal formula. In order to obtain a high number of viable cells and a prolonged shelf life in the designed product, it is required to apply technological procedures using high temperatures or abrupt changes of them, which result in conditions that are different from the optimal growth temperature and can affect the metabolic capabilities of the bacteria when administered to the host in order to reestablish the ecological mucosa. The aim of this work was to evaluate the behavior of 30 different species and strains of autochthonous beneficial vaginal lactobacilli (BVL) when exposed to high temperatures, determine their survival capabilities and analyze their pre-adaptation to those temperatures, in order that they still maintain their viability after technological processes and further conservation. BVL were exhibited to temperatures higher than optimal, with the purpose of evaluating their growth kinetics and parameters. Later, they were exposed to higher temperatures, and then, returned to their optimal, to determine if they were able to grow again. The strains that showed higher resistance were selected, and their viability and beneficial properties studied further. The growth kinetics of strains exposed to higher temperatures showed different patterns, which provided evidence that the thermal adaptation is strain-dependent and is not related to any particular species and/or metabolic group in which the strains were taxonomically classified. The pre-adaptive step allowed the growth of some of the strains, preserving their viability and probiotic properties after the high temperatures were applied. The results shows that BVL can be exposed to high temperatures used in different technological processes that are applied for pharmabiotic formulations, such as spray dried or vacuum rotary evaporation, and/or during the conservation period. The results obtained indicate that some specific BVL strains resist high temperatures and grow afterwards at optimal conditions.

Assessment the viability properties of Lactobacillus casei strain using labneh as a carrier.

BACKGROUND: Our study was conducted in two stages; the first stage was to examine the fructose fermentation profile by Lactobacillus (Lb.) casei FEGY9973. The second stage was to investigate the viability properties of Lb. casei either during cold storage of labneh or under simulated gastrointestinal tract (GIT) conditions. METHODS: Labneh as a carrier medium was classified into four treatments; the first one con- tained 2% free cells of Lb. casei as a control. The second, third and fourth treatments used 2% of encapsulated cells of Lb. casei with different capsule materials, including alginate-milk, sodium alginate and κ-carrageenan served as T1, T2 and T3 respectively. The physiochemical, microbiological and sensory properties of labneh during 15 days of cold storage were shown. Moreover, the viability of free and encapsulated Lb. casei sub- jected to some manufacturing and simulated GIT conditions was tested. RESULTS: It was revealed that lactate was the major metabolite in the medium for colonic fermentation, where- as no amounts of ethanol could be detected. Moreover, labneh samples including free cells of Lb. casei had lower pH values than treatments containing microcapsules of Lb. casei. The levels of moisture, acetaldehyde and diacetyle in treatments with different encapsulated materials were increased during the cold storage period. Accordingly, labneh samples with encapsulated Lb. casei had higher sensory scores than the control. In addition, labneh samples with Lb. casei in milk-alginate microcapsules showed a high viability during cold storage and under simulated GIT conditions. A significant decrease in the viability of free or encapsulated Lb. casei was observed at 15 days of cold storage. CONCLUSIONS: Encapsulated Lb. casei by alginate-milk was more resistant during the cold storage period and under simulated gastric conditions than the other two treatments.