Tailoring the probiotic potential of non-starter Lactobacillus strains from ripened Parmigiano Reggiano cheese by in vitro screening and principal component analysis

Predicting the immunomodulatory activity of probiotic lactic acid bacteria using supervised machine learning in a Cornu aspersum snail model

In the process of screening for probiotic strains, there are no clearly established bacterial phenotypic markers which could be used for the prediction of their in vivo mechanism of action. In this work, we demonstrate for the first time that Machine Learning (ML) methods can be used for accurately predicting the in vivo immunomodulatory activity of probiotic strains based on their cell surface phenotypic features using a snail host-microbe interaction model. A broad range of snail gut presumptive probiotics, including 240 new lactic acid bacterial strains (Lactobacillus, Leuconostoc, Lactococcus, and Enterococcus), were isolated and characterized based on their capacity to withstand snails' gastrointestinal defense barriers, such as the pedal mucus, gastric mucus, gastric juices, and acidic pH, in association with their cell surface hydrophobicity, autoaggregation, and biofilm formation ability. The implemented ML pipeline predicted with high accuracy (88 %) strains with a strong capacity to enhance chemotaxis and phagocytic activity of snails' hemolymph cells, while also revealed bacterial autoaggregation and cell surface hydrophobicity as the most important parameters that significantly affect host immune responses. The results show that ML approaches may be useful to derive a predictive understanding of host-probiotic interactions, while also highlighted the use of snails as an efficient animal model for screening presumptive probiotic strains in the light of their interaction with cellular innate immune responses.

Characterization of Genomic, Physiological, and Probiotic Features of Lactiplantibacillus plantarum JS21 Strain Isolated from Traditional Fermented Jiangshui

This study aimed to understand the genetic and metabolic traits of a Lactiplantibacillus plantarum JS21 strain and its probiotic abilities through laboratory tests and computer analysis. L. plantarum JS21 was isolated from a traditional fermented food known as "Jiangshui" in Hanzhong city. In this research, the complete genetic makeup of JS21 was determined using Illumina and PacBio technologies. The JS21 genome consisted of a 3.423 Mb circular chromosome and five plasmids. It was found to contain 3023 protein-coding genes, 16 tRNA genes, 64 rRNA operons, 40 non-coding RNA genes, 264 pseudogenes, and six CRISPR array regions. The GC content of the genome was 44.53%. Additionally, the genome harbored three complete prophages. The evolutionary relationship and the genome collinearity of JS21 were compared with other L. plantarum strains. The resistance genes identified in JS21 were inherent. Enzyme genes involved in the Embden-Meyerhof-Parnas (EMP) and phosphoketolase (PK) pathways were detected, indicating potential for facultative heterofermentative pathways. JS21 possessed bacteriocins plnE/plnF genes and genes for polyketide and terpenoid assembly, possibly contributing to its antibacterial properties against Escherichia coli (ATCC 25922), Escherichia coli (K88), Staphylococcus aureus (CMCC 26003), and Listeria monocytogenes (CICC 21635). Furthermore, JS21 carried genes for Na+/H+ antiporters, F0F1 ATPase, and other stress resistance genes, which may account for its ability to withstand simulated conditions of the human gastrointestinal tract in vitro. The high hydrophobicity of its cell surface suggested the potential for intestinal colonization. Overall, L. plantarum JS21 exhibited probiotic traits as evidenced by laboratory experiments and computational analysis, suggesting its suitability as a dietary supplement.

The anticancer effect of potential probiotic L. fermentum and L. plantarum in combination with 5-fluorouracil on colorectal cancer cells

5-Fluorouracil (5-FU) is an effective chemotherapy drug in the treatment of colorectal cancer (CRC). However, auxiliary or alternative therapies must be sought due to its resistance and potential side effects. Certain probiotic metabolites exhibit anticancer properties. In this study evaluated the anticancer and potential therapeutic activities of cell extracts potential probiotic strains, Limosilactobacillus fermentum and Lactiplantibacillus plantarum isolated from the mule milk and the standard probiotic strain Lacticaseibacillus rhamnosus GG (LGG) against the human colon cancer cell line (HT-29) and the normal cell line (HEK-293) alone or in combination with 5-FU. In this study, L. plantarum and L. fermentum, which were isolated from mule milk, were identified using biochemical and molecular methods. Their probiotic properties were investigated in vitro and compared with the standard probiotic strain of the species L. rhamnosus GG. The MTT assay, acridine orange/ethidium bromide (AO/EB) fluorescent staining, and flow cytometry were employed to measure the viability of cell lines, cell apoptosis, and production rates of Th17 cytokines, respectively. The results demonstrated that the combination of lactobacilli cell extracts and 5-FU decreased cell viability and induced apoptosis in HT-29 cells. Furthermore, this combination protected HEK-293 cells from the cytotoxic effects of 5-FU, enhancing their viability and reducing apoptosis. Moreover, the combination treatment led to an increase in the levels of IL-17A, IFN-γ, and TNF-α, which can enhance anti-tumor immunity. In conclusion, the cell extracts of the lactobacilli strains probably can act as a potential complementary anticancer therapy.

Evaluation of the probiotic potential of yeast isolated from kombucha in New Zealand

The current study investigated the in vitro probiotic potential of yeast isolated from kombucha, a tea beverage fermented with a symbiotic culture of acetic acid bacteria and yeast. A total of 62 yeast strains were previously isolated from four different commercial kombucha samples sold in New Zealand. Fifteen representative isolates belonging to eight different species were evaluated for their growth under different conditions (temperature, low pH, concentrations of bile salts, and NaCl). Cell surface characteristics, functional and enzymatic activities of the selected strains were also studied in triplicate experiments. Results showed that six strains (Dekkera bruxellensis LBY1, Sachizosaccharomyces pombe LBY5, Hanseniaspora valbyensis DOY1, Brettanomyces anomalus DOY8, Pichia kudraivzevii GBY1, and Saccharomyces cerevisiae GBY2) were able to grow under low-acid conditions (at pH 2 and pH 3) and in the presence of bile salts. This suggests their potential to survive passage through the human gut. All 15 strains exhibited negative enzymatic activity reactions (haemolytic, gelatinase, phospholipase, and protease activities), and thus, they can be considered safe to consume. Notably, two of the fifteen strains (Pichia kudraivzevii GBY1 and Saccharomyces cerevisiae GBY2) exhibited desirable cell surface hydrophobicity (64.60-83.87%), auto-aggregation (>98%), co-aggregation, resistance to eight tested antibiotics (ampicillin, chloramphenicol, colistin sulphate, kanamycin, nalidixic acid, nitrofurantoin, streptomycin, and tetracycline), and high levels of antioxidant activities (>90%). Together, our data reveal the probiotic activities of two yeast strains GBY1 and GBY2 and their potential application in functional food production.

Probiotic potential and wound-healing activity of Pediococcus pentosaceus strain AF2 isolated from Herniaria glabra L. which is traditionally used to make yogurt

Probiotics have been a part of our lives for centuries, primarily through fermented foods. They find applications in various fields such as food, healthcare, and agriculture. Nowadays, their utilization is expanding, highlighting the importance of discovering new bacterial strains with probiotic properties suitable for diverse applications. In this study, our aim was to isolate new probiotic bacteria. Herniaria glabra L., a plant traditionally used for yogurt making in some regions and recognized in official medicine in many countries, was chosen as the source for obtaining probiotic bacteria. We conducted bacterial isolation from the plant, molecularly identified the isolated bacteria using 16S rRNA sequencing, characterized their probiotic properties, and assessed their wound-healing effects. As a result of these studies, we identified the bacterium isolated from the plant as Pediococcus pentosaceus strain AF2. We found that the strain AF2 exhibited high resistance to conditions within the gastrointestinal tract. Our reliability analysis showed that the isolate had γ-hemolytic activity and displayed sensitivity to certain tested antibiotics. At the same time, AF2 did not show gelatinase and DNase activity. We observed that the strain AF2 produced metabolites with inhibitory activity against E. coli, B. subtilis, P. vulgaris, S. typhimurium, P. aeruginosa, K. pneumoniae, E. cloacae, and Y. pseudotuberculosis. The auto-aggregation value of the strain AF2 was calculated at 73.44%. Coaggregation values against E. coli and L. monocytogenes bacteria were determined to be 56.8% and 57.38%, respectively. Finally, we tested the wound-healing effect of the strain AF2 with cell culture studies and found that the strain AF2 promoted wound healing.

Milk and Its Derivatives as Sources of Components and Microorganisms with Health-Promoting Properties: Probiotics and Bioactive Peptides

Milk is a source of many valuable nutrients, including minerals, vitamins and proteins, with an important role in adult health. Milk and dairy products naturally containing or with added probiotics have healthy functional food properties. Indeed, probiotic microorganisms, which beneficially affect the host by improving the intestinal microbial balance, are recognized to affect the immune response and other important biological functions. In addition to macronutrients and micronutrients, biologically active peptides (BPAs) have been identified within the amino acid sequences of native milk proteins; hydrolytic reactions, such as those catalyzed by digestive enzymes, result in their release. BPAs directly influence numerous biological pathways evoking behavioral, gastrointestinal, hormonal, immunological, neurological, and nutritional responses. The addition of BPAs to food products or application in drug development could improve consumer health and provide therapeutic strategies for the treatment or prevention of diseases. Herein, we review the scientific literature on probiotics, BPAs in milk and dairy products, with special attention to milk from minor species (buffalo, sheep, camel, yak, donkey, etc.); safety assessment will be also taken into consideration. Finally, recent advances in foodomics to unveil the probiotic role in human health and discover novel active peptide sequences will also be provided.

Evaluation of penicillin-resistance and probiotic traits in Lactobacillus plantarum during laboratory evolution

The aim of this study was to obtain the Lactobacillus plantarum ATCC14917 with high-level resistance to penicillin and evaluate their probiotic traits using laboratory evolution assay and whole-genome sequencing. In penicillin environment, the minimum inhibitory concentration (MIC) of L. plantarum to penicillin increased from 1 μg/mL to 16 μg/mL and remained stable after the removal of antibiotic pressure, suggesting that the resistance acquisition to penicillin was an irreversible process. Subsequently, change of probiotic characteristics was further evaluated, and the results showed that the acid tolerance, bile tolerance and adhesion ability were significantly declined in the highly resistant strains. Whole-genome sequencing indicated that genes encoding hypothetical protein, LPXTG-motif cell wall anchor domain protein and acetyltransferase were detected in highly resistant L. plantarum, and these genes were still present after the following subculture in the absence of penicillin, suggesting that these three mutants might be the main reason for the development of penicillin resistance. The homology-based analysis of surrounding DNA regions of mutant genes was further performed and indicated that no resistant genes were located on mobile elements in evolved L. plantarum strains, signifying that the spread of antibiotic resistance genes in the gut would not occur for these mutant genes. This study provided a basis for the combined use of highly resistant L. plantarum and penicillin in the treatment of pathogen induced gut diseases.

Diversity of the Microbiota of Traditional Izmir Tulum and Izmir Brined Tulum Cheeses and Selection of Potential Probiotics

High-throughput DNA sequencing (HTS) was used to study the microbial diversity of commercial traditional Izmir Tulum (IT) and Izmir Brined Tulum (IBT) cheeses from Izmir, Türkiye. Simultaneously, cultivation-dependent methods were used to isolate, identify and characterize bacterial strains displaying probiotic potential. At the phylum level, Firmicutes dominated the microbiota of both cheese types comprising >98% of the population. Thirty genera were observed, with Streptococcus being the most abundant genus and with Streptococcus thermophilus and S. infantarius subsp. infantarius being the most abundant species. Genera, including Bifidobacterium and Chryseobacterium, not previously associated with IT and IBT, were detected. IT cheeses displayed higher operational taxonomic units (OTUs; Richness) and diversity index (Simpson) than IBT cheeses; however, the difference between the diversity of the microbiota of IT and IBT cheese samples was not significant. Three Lacticaseibacillus paracasei strains isolated from IBT cheeses exhibited probiotic characteristics, which included capacity to survive under in vitro simulated gastrointestinal conditions, resistance to bile salts and potential to adhere to HT-29 human intestinal cells. These findings demonstrate that Tulum cheeses harbor bacterial genera not previously reported in this cheese and that some strains display probiotic characteristics.

Probiotic Properties of Pediococcus pentosaceus JBCC 106 and Its Lactic Acid Fermentation on Broccoli Juice

To understand the biological roles of Pediococcus pentosaceus strains as probiotics isolated from the traditional Korean fermented food, Jangajji, Pediococcus pentosaceus was selected based on its high cinnamoyl esterase (CE) and antioxidant activities. The acid and bile stability, intestinal adhesion, antagonistic activity against human pathogens, cholesterol-lowering effects, and immune system stimulation without inflammatory effects were evaluated. Nitric oxide (NO) levels were measured in co-culture with various bacterial stimulants. Fermentation ability was measured by using a broccoli matrix and the sulforaphane levels were measured. Resistance to acidic and bilious conditions and 8% adherence to Caco-2 cells were observed. Cholesterol levels were lowered by 51% by assimilation. Moreover, these strains exhibited immunomodulatory properties with induction of macrophage TNF-α and IL-6 and had microstatic effects on various pathogens. Co-culture with various bacterial stimulants resulted in increased NO production. Fermentation activity was increased with the strains, and higher sulforaphane levels were observed. Therefore, in the future, the applicability of the selected strain to broccoli matrix-based fermented functional foods should be confirmed.

Probiotic and technological characterization of selected Lactobacillus strains isolated from different egyptian cheeses

BACKGROUND

Fresh milk and natural environmental conditions are used to produce traditional cheeses. Such cheeses are produced by dozens of different types of microbes. Non-starter lactobacilli are the most responsible genus of lactic acid bacteria exhibiting key technological and health promoting traits. The purpose of this study is to isolate Lactobacillus bacteria from conventional Egyptian cheeses and analyse their probiotic potential and technological properties.

RESULTS

Lactobacillus isolates (33 isolates) were isolated from different Egyptian cheeses. Our results revealed that 18.18% of the isolates were fast-acidifying, 30.3% were medium-acidifying and 51.5% were slow-acidifying isolates. The results of autolytic activity showed that 24.3% of the isolates were good autolysis, 33.3% were fair autolysis, while 42.4% were poor autolysis. Fifteen isolates produced exopolysaccharides, while 9 isolates exhibited antimicrobial activities against Lactobacillus bulgaricus 340. All the isolates were resistant to pH 3 for 3 h except isolate No. 15 (MR4). The growth rate of the isolates ranged from 42.25 to 85.25% at 0.3% bile salts after 3 h of incubation. The surviving percentage of the Lactobacillus isolates decreased with increasing incubation time or the percentage of bile salts greater than 0.3%. All the isolates grew after incubation in artificial gastric and intestinal fluids. The auto-aggregation of 15 isolates ranged from 43.13 to 72.77%. Lacticaseibacillus paracasei BD3, Lactiplantibacillus plantarum BR4 and Limosilactobacillus fermentum MR2 were sensitive to the majority of the tested antibiotics and showed good bile salt hydrolase activity.

CONCLUSION

L. paracasei BD3, L. plantarum BR4 and L. fermentum MR2 were isolated from Egyptian cheeses and showed probiotic and technological characterization, which are valuable for their practical application as starters, adjunct and protective cultures in cheese making.

Probiotic potential of Lactobacillus plantarum DMR14 for preserving and extending shelf life of fruits and fruit juice

The harmful effects of chemical preservatives are driving the need for natural ones. To meet this demand, probiotic lactic acid bacteria (LAB) were isolated from fermented oats in this study. The goals of this study were to separate and identify probiotic LAB from fermented oats, to determine how effective these LAB are at combating pathogenic microorganisms in vitro, and to investigate their preservative capacity by applying the bacterium's cell-free supernatant (CFS) to specific fruits and fruit juice. The isolated strain was identified as Lactobacillus plantarum DMR14 using morphological, biochemical, and molecular investigation. Antimicrobial, antibiofilm, anti-oxidant, pH tolerance, and antibiotic resistance assays were used to evaluate the strain's probiotic potential, showing that Lactobacillus plantarum DMR14 had the strongest antagonistic and anti-biofilm capacity against Shigella boydii. Furthermore, the bacteriocin-containing compounds, cell-free supernatant (CFS) of the LAB, were tested against three fruits and one fruit juice, with the cell-free supernatant (CFS) of the bacterium lengthening the shelf life of the fruits compared to the untreated ones. Furthermore, while the concentration of coliform bacteria decreased in the treated sugarcane juice, an increase in the concentration of lactic acid bacteria suggested that the strain may be used as a fruit preservative in food industries.

Exploring the Potential of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 as Promising Psychobiotics Using SHIME

Psychobiotics are probiotics that have the characteristics of modulating central nervous system (CNS) functions or reconciled actions by the gut-brain axis (GBA) through neural, humoral and metabolic pathways to improve gastrointestinal activity as well as anxiolytic and even antidepressant abilities. The aim of this work was to evaluate the effect of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 on the gut microbiota of mildly anxious adults using SHIME^®. The protocol included a one-week control period and two weeks of treatment with L. helveticus R0052 and B. longum R0175. Ammonia (NH4+), short chain fatty acids (SCFAs), gamma-aminobutyric acid (GABA), cytokines and microbiota composition were determined. Probiotic strains decreased significantly throughout the gastric phase. The highest survival rates were exhibited by L. helveticus R0052 (81.58%; 77.22%) after the gastric and intestinal phase when compared to B. longum (68.80%; 64.64%). At the genus level, a taxonomic assignment performed in the ascending colon in the SHIME^® model showed that probiotics (7 and 14 days) significantly (p < 0.005) increased the abundance of Lactobacillus and Olsenella and significantly decreased Lachnospira and Escheria-Shigella. The probiotic treatment (7 and 14 days) decreased (p < 0.001) NH₄⁺ production when compared to the control period. For SCFAs, we observed after probiotic treatment (14 days) an increase (p < 0.001) in acetic acid production and total SCFAs when compared to the control period. Probiotic treatment increased (p < 0.001) the secretion of anti-inflammatory (IL-6 and IL-10) and decreased (p < 0.001) pro-inflammatory cytokines (TNF-alpha) when compared to the control period. The gut-brain axis plays an important role in the gut microbiota, producing SCFAs and GABA, stimulating the production of anti-anxiety homeostasis. The signature of the microbiota in anxiety disorders provides a promising direction for the prevention of mental illness and opens a new perspective for using the psychobiotic as a main actor of therapeutic targets.

First isolation of a probiotic candidate Enterococcus mundtii from Herniaria glabra L. and evaluation of its wound healing activity

In this study focused on probiotic properties of bacterium isolated from Herniaria glabra L. is a medicinal plant. The bacterium was isolated from H. glabra, and it was identified using the molecular method as Enterococcus mundtii AF-1 strain. Antibiotic sensitivity tests showed that AF-1 strain was sensitive to streptomycin, tobramycin, gentamicin, imipenem, erythromycin, and ciprofloxacin. The strain exhibited γ-haemolytic activity. These results show that the strain can be considered safe. The AF-1 strain showed inhibitory activity against some pathogens, including Bacillus subtilis, Klebsiella pneumoniae, and Yersinia pseudotuberculosis. Additionally, AF-1 strain exhibited high tolerance to low pH, pepsin, pancreatin, and bile salts. These properties showed that the strain may survival under the gastrointestinal conditions. The strain showed 40% DPPH free radical scavenging activity. The autoaggregation rate of the strain was 72.46% and the strain exhibited the high coaggregation rate (70.77% with Escherichia coli, and 63.78% with Listeria monocytogenesis). AF-1 strain showed 38.10% adhesion towards n-hexane, and 47.62% adhesion toward chloroform. It has been found to have moderate hydrophobicity. These results demonstrated the beneficial colonization ability of the strain in the gut. Furthermore, it was observed that living cells of AF-1 strain showed healing activity in the artificial wound area. Result of studies, it is seen that AF-1 strain might be excellent a probiotic candidate.

Functional Fermented Milk with Fruit Pulp Modulates the In Vitro Intestinal Microbiota

The effect of putative probiotic fermented milk (FM) with buriti pulp (FMB) or passion fruit pulp (FMPF) or without fruit pulp (FMC) on the microbiota of healthy humans was evaluated. FM formulations were administered into a simulator of the human intestinal microbial ecosystem (SHIME^®) to evaluate the viability of lactic acid bacteria (LAB), microbiota composition, presence of short-chain fatty acids (SCFA), and ammonium ions. The probiotic LAB viability in FM was affected by the addition of the fruit pulp. Phocaeicola was dominant in the FMPF and FMB samples; Bifidobacterium was related to FM formulations, while Alistipes was associated with FMPF and FMB, and Lactobacillus and Lacticaseibacillus were predominant in FMC. Trabulsiella was the central element in the FMC, while Mediterraneibacter was the central one in the FMPF and FMB networks. The FM formulations increased the acetic acid, and a remarkably high amount of propionic and butyric acids were detected in the FMB treatment. All FM formulations decreased the ammonium ions compared to the control; FMPF samples stood out for having lower amounts of ammonia. The probiotic FM with fruit pulp boosted the beneficial effects on the intestinal microbiota of healthy humans in addition to increasing SCFA in SHIME^® and decreasing ammonium ions, which could be related to the presence of bioactive compounds.

Lacticaseibacillus rhamnosus CA15 (DSM 33960) as a Candidate Probiotic Strain for Human Health

Lactobacilli with probiotic properties have emerged as promising tools for both the prevention and treatment of vaginal dysbiosis. The present study aimed to study the in vitro probiotic potential of the Lacticaseibacillus rhamnosus CA15 (DSM 33960) strain isolated from a healthy vaginal ecosystem. The strain was evaluated for both functional (antagonistic activity against pathogens; H₂O₂, organic acid, and lactic acid production; antioxidant and anti-inflammatory activities; ability to adhere to intestinal mucus and to both CaCo-2 and VK7/E6E7 cell lines; exopolysaccharide production; surface properties; and ability to survive during gastrointestinal transit) and safety (hemolytic, DNase, and gelatinase activities; mucin degradation ability; production of biogenic amines; and resistance to antimicrobials) characteristics. Data revealed that the tested strain was able to antagonize a broad spectrum of vaginal pathogens. In addition, the adhesion capacity to both vaginal and intestinal cell lines, as well as anti-inflammatory and antioxidant activities, was detected. The ability of the Lacticaseibacillus rhamnosus CA15 (DSM 33960) strain to survive under harsh environmental conditions occurring during the gastrointestinal passage suggests its possible oral delivery. Thus, in vitro data highlighted interesting probiotic properties of the CA15 (DSM 33960) strain, which could represent a valuable candidate for in vivo vaginal infections treatment.

Assessment of the safety and probiotic properties of Roseburia intestinalis: A potential “Next Generation Probiotic”

Roseburia intestinalis is an anaerobic bacterium that produces butyric acid and belongs to the phylum Firmicutes. There is increasing evidence that this bacterium has positive effects on several diseases, including inflammatory bowel disease, atherosclerosis, alcoholic fatty liver, colorectal cancer, and metabolic syndrome, making it a potential “Next Generation Probiotic.” We investigated the genomic characteristics, probiotic properties, cytotoxicity, oral toxicity, colonization characteristics of the bacterium, and its effect on the gut microbiota. The genome contains few genes encoding virulence factors, three clustered regularly interspaced short palindromic repeat (CRISPR) sequences, two Cas genes, no toxic biogenic amine synthesis genes, and several essential amino acid and vitamin synthesis genes. Seven prophages and 41 genomic islands were predicted. In addition to a bacteriocin (Zoocin A), the bacterium encodes four metabolic gene clusters that synthesize short-chain fatty acids and 222 carbohydrate-active enzyme modules. This bacterium is sensitive to antibiotics specified by the European Food Safety Authority, does not exhibit hemolytic or gelatinase activity, and exhibits some acid resistance. R. intestinalis adheres to intestinal epithelial cells and inhibits the invasion of certain pathogens. In vitro experiments showed that the bacterium was not cytotoxic. R. intestinalis did not affect the diversity or abundance of the gut flora. Using the fluorescent labelling method, we discovered that R. intestinalis colonizes the cecum and mucus of the colon. An oral toxicity study did not reveal any obvious adverse effects. The lethal dose (LD)50 of R. intestinalis exceeded 1.9 × 10⁹ colony forming units (CFU)/kg, whereas the no observed adverse effect level (NOAEL) derived from this study was 1.32 × 10⁹ CFU/kg/day for 28 days. The current research shows that, R. intestinalis is a suitable next-generation probiotic considering its probiotic properties and safety.

The Detection of Potential Native Probiotics Lactobacillus spp. against Salmonella Enteritidis, Salmonella Infantis and Salmonella Kentucky ST198 of Lebanese Chicken Origin

Salmonella continues to be a major threat to public health, especially with respect to strains from a poultry origin. In recent years, an increasing trend of antimicrobial resistance (AMR) in Salmonella spp. was observed due to the misuse of antibiotics. Among the approaches advised for overcoming AMR, probiotics from the Lactobacillus genus have increasingly been considered for use as effective prophylactic and therapeutic agents belonging to the indigenous microbiota. In this study, we isolated lactobacilli from the ilea and ceca of hens and broilers in order to evaluate their potential probiotic properties. Four species were identified as Limosilactobacillusreuteri (n = 22, 45.8%), Ligilactobacillussalivarius (n = 20, 41.6%), Limosilactobacillus fermentum (n = 2, 4.2%) and Lactobacillus crispatus (n = 1, 2%), while three other isolates (n = 3, 6.25%) were non-typable. Eight isolates, including Ligilactobacillussalivarius (n = 4), Limosilactobacillusreuteri (n = 2), L. crispatus (n = 1) and Lactobacillus spp. (n = 1) were chosen on the basis of their cell surface hydrophobicity and auto/co-aggregation ability for further adhesion assays using the adenocarcinoma cell line Caco-2. The adhesion rate of these strains varied from 0.53 to 10.78%. Ligilactobacillussalivarius A30/i26 and 16/c6 and Limosilactobacillus reuteri 1/c24 showed the highest adhesion capacity, and were assessed for their ability to compete in and exclude the adhesion of Salmonella to the Caco-2 cells. Interestingly, Ligilactobacillussalivarius 16/c6 was shown to significantly exclude the adhesion of the three Salmonella serotypes, S. Enteritidis, S. Infantis and S. Kentucky ST 198, to Caco-2 cells. The results of the liquid co-culture assays revealed a complete inhibition of the growth of Salmonella after 24 h. Consequently, the indigenous Ligilactobacillussalivarius 16/c6 strain shows promising potential for use as a preventive probiotic added directly to the diet for the control of the colonization of Salmonella spp. in poultry.

In vitro evaluation of probiotic properties and antioxidant activities of Bifidobacterium strains from infant feces in the Uyghur population of northwestern China

Purpose

Bifidobacterium is an important probiotic used in food and medicine production. The probiotic properties of bifidobacteria are strain specific, so it is necessary to evaluate the probiotic properties of bifidobacteria isolated from specific populations, especially when developing products suitable for specific populations. The objective of this study was to evaluate the probiotic potential and safety of bifidobacteria isolated from healthy Uyghur infants from northwestern China.

Methods

In this study, antimicrobial activity, antibiotic sensitivity, hemolytic, acid and bile tolerance, hydrophobicity, co-aggregation, auto-aggregation, and antioxidant activity were evaluated.

Results

Based on antagonistic activity spectrum against seven intestinal pathogenic bacteria, 14 excellent strains were initially selected. Among 14 strains, four bifidobacteria strains (BF17-4, BF52-1, BF87-3, and BF88-5) were superior to strain Lactobacillus rhamnosus GG in cell surface hydrophobicity and auto-aggregation percentages and close to strain GG in co-aggregation with Escherichia coli EPEC O127: K63 (CICC 10411). The antioxidant activities of each of the 14 bifidobacteria strains varied with the cell components. Most of the strains were sensitive to all the antimicrobials tested, except kanamycin and amikacin.

Conclusion

BF17-4 and BF52-1 are good candidates for further in vivo studies and further used in functional foods.

Advantages and disadvantages of non-starter lactic acid bacteria from traditional fermented foods: Potential use as starters or probiotics

Traditional fermented foods are a significant source of starter and/or non-starter lactic acid bacteria (nsLAB). Moreover, these microorganisms are also known for their role as probiotics. The potential of nsLAB is huge; however, there are still challenges to be overcome with respect to characterization and application. In the present review, the most important steps that autochthonous lactic acid bacteria isolated from fermented foods need to overcome, to qualify as novel starter cultures, or as probiotics, in food technology and biotechnology, are considered. These different characterization steps include precise identification, detection of health-promoting properties, and safety evaluation. Each of these features is strain specific and needs to be accurately determined. This review highlights the advantages and disadvantages of nsLAB, isolated from traditional fermented foods, discussing safety aspects and sensory impact.

In Vitro Probiotic Characteristics and Whole Genome Sequence Analysis of Lactobacillus Strains Isolated from Cattle-Yak Milk

Cattle-yak milk is an important raw material and an indispensable source of high-quality food for local farmers and herdsmen to produce ghee, milk residue, yogurt, and other dairy products. In this study, Lactobacillus strains were isolated from cattle-yak milk for potential probiotic candidates using a series of in vitro tests, including probiotic characterization and safety evaluation (antibiotic susceptibility and hemolytic ability). The results found that the Lactobacillus rhamnosus CY12 strain showed a high survival rate in bile salts, under acid conditions, and in the gastrointestinal juice environment, as well as showing high antimicrobial activity and adhesive potential. The safety evaluation showed that all strains were considered non-hemolytic. In addition, the whole-genome sequencing indicated that the strain CY12 spanned 2,506,167 bp, with an average length of 881 bp; the GC content in the gene region (%) was 47.35, contained 1347 protein-coding sequences, and accounted for 85.72% of the genome. The genome annotation showed that genes mainly focused on the immune system process, metabolic process, carbohydrate utilization, carbon metabolism, galactose metabolism, and biological adhesion, etc. This study revealed that the Lactobacillus rhamnosus CY12 strain might be an excellent potential probiotic in the development of feed additives for animals and has the ability to promote health.

The Microbiota of Grana Padano Cheese. A Review

Grana Padano (GP) is the most appreciated and marketed cheese with Protected Designation of Origin in the world. The use of raw milk, the addition of undefined cultures (defined as 'sieroinnesto naturale'), the peculiar manufacturing proces, and the long ripening make the cheese microbiota play a decisive role in defining the quality and the organoleptic properties of the product. The knowledge on the microbial diversity associated with GP has been the subject, in recent years, of several studies aimed at understanding its composition and characteristics in order, on the one hand, to improve its technological performances and, on the other hand, to indirectly enhance the nutritional quality of the product. This review aims to briefly illustrate the main available knowledge on the composition and properties of the GP microbiota, inferred from dozens of studies carried out by both classical microbiology techniques and metagenomic analysis. The paper will essentially, but not exclusively, be focused on the lactic acid bacteria (LAB) derived from starter (SLAB) and the non-starter bacteria, both lactic (NSLAB) and non-lactic, of milk origin.

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

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&nbsp;paracasei strains NSMJ15 and NFFJ04, Lentilactobacillus parabuchneri NSMJ16, Levilactobacillus&nbsp;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.

Complete genome analysis of Lactobacillus fermentum YLF016 and its probiotic characteristics

Lactobacillus fermentum (L. fermentum) YLF016 is a well-characterized probiotic with several favorable characteristics. This study aimed to analyze the probiotic characteristics of L. fermentum and uncover the genes implicated in its potential probiotic ability on the base of its genomics features. The complete genome of L. fermentum YLF016 was found to have a circular chromosome of 2,094,354 bp, and 51.46% G + C content without any plasmid. Its chromosome contained 2,130 predicted protein-encoding genes, 58 tRNA, and 15 rRNA-encoding genes. Also, it was found to have many other probiotic properties, such as a high survival rate in the gastrointestinal tract with strong adherence to intestinal cells, antibacterial activity against pathogens, and antioxidant activity. Moreover, the genome sequence analysis demonstrated specific genes coding for carbon metabolism pathway, genetic adaption, stress resistance, and adhesive ability. Further analysis revealed its non-hemolytic activity and its non-functional ability of virulence factors. In conclusion, L. fermentum YLF016 possesses many valuable probiotic properties that refer to its potential probiotic ability.

Probiotic and Antioxidant Properties of Lactic Acid Bacteria Isolated from Indigenous Fermented Tea Leaves (Miang) of North Thailand and Promising Application in Synbiotic Formulation

Miang, a traditional fermented tea from Northern Thailand, potentially hosts beneficial probiotic bacteria. A total of 133 isolates of lactic acid bacteria (LAB) isolated from Miang were evaluated for probiotic potential. Among them, 5 strains showed high tolerance to bile and acidic conditions and were selected for further evaluation. All selected strains showed inhibitory activity against human pathogens, including Bacillus cereus, Staphylococcus aureus, and Salmonella ser. Typhimurium. Nucleotide sequences analysis of the 16S rRNA gene revealed that 3 isolates were identified as Lactobacillus pentosus; the remaining were L. plantarum and Pediococcus pentosaceus, respectively. All 5 strains showed a high survival rate of more than 90% when exposed to simulated gastrointestinal conditions and were also susceptible to antibiotics such as erythromycin, tetracycline, and gentamycin, and resistant to vancomycin, streptomycin, and polymycin. In addition, the selected isolates exhibited different degrees of cell surface hydrophobicity (58.3–92.9%) and auto-aggregation (38.9–46.0%). The antioxidant activity reflected in DPPH scavenging activities of viable cells and their cell-free culture supernatants (CFCS) were also found in selected LAB isolates. Moreover, selected LAB isolates showed ability to grow on commercial prebiotics (GOS, FOS or XOS). The preliminary study of spray-drying using cyclodextrin as thermoprotectant suggested that all strains can be designed as a powdered formulation. L. pentosus A14-6 was the best strain, with high tolerance against simulated gastrointestinal conditions, high cell surface hydrophobicity, effective response to tested commercial oligosaccharides, especially XOS, and the highest cell antioxidant properties. L. pentosus A14-6 was therefore targeted for further applications in food and synbiotic applications.

Optimization of bioprocess of Schleiferilactobacillus harbinensis Ca12 and its viability in frozen Brazilian berries (Açai, Euterpe oleracea Mart.)

Amazonian palm berries (açaí, Euterpe oleracea Mart.) are fruits with high nutritional value and antioxidant activity and have aroused the interest of consumers, popularizing fruit pulps enriched with probiotics. Amazonian palm berries (açaí, Euterpe oleracea Mart.) are fruits with high nutritional potential, providing a source of carbohydrates, fibers, proteins, lipids, vitamins, and minerals. Furthermore, açai provides several health benefits, including antioxidant activity. Nutritionally enhanced foods have aroused the interest of consumers, popularizing fruit pulps enriched with probiotics. Probiotics are dietary supplements consisting of live, beneficial microorganisms in the host which improve the intestinal microbiota. The objective of this study was to isolate, identify, and characterize the probiotic potential of an isolated Schleiferilactobacillus harbinensis strain (dubbed Ca12) and provide an optimized bioprocess for its production, using the complete factorial and central rotational compound design to supplement the frozen açai pulp. The isolated strain S. harbinensis Ca12 presented adequate resistance to gastric juice and bile salts, microbial activity against different Candida strains, self-aggregation and coaggregation properties, high adhesion in HT-29 cells, and 35% inhibition of Salmonella in HT-29 cells. When optimized, the cellular biomass production of the S. harbinensis Ca12 strain was approximately 600% higher than the unsupplemented whey, with a production of 3.6 × 1010 CFU mL^-1. The S. harbinensis Ca12 strain's viability in the creamy and traditional frozen açai pulp was shown to be stable for up to 6 months at 20 °C. The impact of this study involved for the first time the S. harbinensis Ca12 described in the Brazilian cocoa pulp with activity against Candida albicans of clinical importance, creating the potential of a new functional food with important benefits to human health as prevention for candidiasis.

Use of Fourier Transform Infrared Spectroscopy for Monitoring the Shelf Life and Safety of Yogurts Supplemented With a Lactobacillus plantarum Strain With Probiotic Potential

The current study aimed to explore the performance of a probiotic Lactobacillus strain as an adjunct culture in yogurt production and to assess Fourier transform infrared spectroscopy as a rapid, noninvasive analytical technique to evaluate the quality and the shelf life of yogurt during storage. In this respect, bovine milk (full-fat) was inoculated with the typical yogurt starter culture without (control case) or with the further addition of Lactobacillus plantarum T571 as an adjunct (probiotic case). The milk was also inoculated with a cocktail mixture of three strains of Listeria monocytogenes in two different initial levels of inoculum, and the fermentation process was followed. Accordingly, yogurt samples were stored at 4 and 12°C, and microbiological, physicochemical, molecular, and sensory analyses were performed during storage. Results showed that the lactic acid bacteria exceeded 7 log CFU/g during storage in all samples, where the probiotic samples displayed higher acidity, lower pH, and reduced counts of Lb. monocytogenes in a shorter period than the control ones at both temperatures. Pulsed-field gel electrophoresis verified the presence of the probiotic strain until the end of storage at both temperatures and in adequate amounts, whereas the survival and the distribution of Listeria strains depended on the case. The sensory evaluation showed that the probiotic samples had desirable organoleptic characteristics, similar to the control. Finally, the spectral data collected from the yogurt samples during storage were correlated with microbiological counts and sensory data. Partial least squares and support vector machine regression and classification models were developed to provide quantitative estimations of yogurt microbiological counts and qualitative estimations of their sensory status, respectively, based on Fourier transform infrared fingerprints. The developed models exhibited satisfactory performance, and the acquired results were promising for the rapid estimation of the microbiological counts and sensory status of yogurt.

Selection of lactic acid bacteria with promising probiotic aptitudes from fruit and ability to survive in different food matrices

Lactic acid bacteria (LAB) are among the most prevalent microorganisms forming the autochthonous microbiota of fruit. This study aimed to select LAB isolates with probiotic aptitudes from apple, banana, grape, and orange through evaluation of in vitro safety, technological, and functional-related properties. The ability of most promising selected isolates to survive in commercial apple and orange juice, meat stew, vegetable puree, and UHT milk during 28 days of refrigeration storage was evaluated. Ninety-three isolates identified preliminarily as LAB were recovered from fruit and 66 of these isolates passed safety tests. Most of these isolates were pre-identified as belonging to Lactobacillus or Enterococcus genus based on MALDI-ToF MS profiling. These 66 isolates were categorized into three homogeneous groups based on a preliminary cluster analysis run with data from experiments to measure technological characteristics. Nine LAB isolates were selected as the most promising for probiotic use based on a principal component analysis run with data from experiments to measure probiotic-related properties. Four of these isolates were sensitive to different antibiotics and identified (16S-rRNA gene sequencing) as Lactobacillus brevis (recently reclassified as L. brevis) or Lactobacillus spp. These 4 selected isolates had high viable counts and high percentages of physiologically active cells in apple and orange juice, beef stew, vegetable puree, and UHT milk during refrigeration storage. The results showed that apple, banana, orange, and grape are potential sources of LAB with aptitudes to be exploited for a possible probiotic use and distinguished abilities to survive in different food matrices.

Probiotic potential of Enterococcus hirae in goat milk and its survival in canine gastrointestinal conditions simulated in vitro

In canine nutrition, the use of goat nutraceutical dairy products is an innovative proposal. Therefore, the objective of this study was to prepare fermented goat milk with probiotic potential in dogs in an in vitro model. A total of 40 lactic acid bacteria (LAB) species were grown, of which 30 were CAP isolates originally from goat milk and 10 were CAN isolates originally from fecal material of newborn dogs. The isolates were selected based on resistance to the simulated canine gastrointestinal condition and acidifying ability. After this preliminary screening, the analyses were performed regarding β-galactosidase and exopolysaccharide formation, diacetyl production, adhesion proteins Mub and mapa, hydrophobicity, DPPH assay, virulence and antibiotic resistance. With these evaluations, four LAB isolates were identified using sequencing of the 16S rRNA gene. These were identified as Enterococcus hirae and were used to produce fermented goat milk. For statistical analysis, the data were analyzed using the Scott-Knott test and also submitted to analysis of variance and the Tukey test (P < 0.05). In the evaluation of goat milk fermented with E. hirae and control, over the 36-day storage period there was a reduction in pH and an increase in acidity, and higher levels of LAB were observed in goat milk fermented with E. hirae. Therefore, both these E. hirae isolates and the fermented goat milk produced showed satisfactory results in vitro, demonstrating probiotic efficiency and food safety for dogs.

Evaluation of indigenous lactic acid bacteria of raw mare milk from pastoral areas in Xinjiang, China, for potential use in probiotic fermented dairy products

In the present study 114 lactic acid bacteria strains, isolated from raw mare milks from pastoral areas for ethnic minorities in northwest China, were screened for probiotic traits, and their characteristics were compared with those of Lactobacillus rhamnosus GG, a commercial strain. Among the 114 strains identified, the most common species was Pediococcus pentosaceus (n = 52), followed by Leuconostoc lactis (n = 35), Lactobacillus helveticus (n = 7), Lactobacillus plantarum (n = 6), Lactobacillus kefiri (n = 5), Lactobacillus curvatus (n = 4), Lactobacillus paracasei (n = 3), and Lactococcus garvieae (n = 3). Based on acid and bile salt tolerance, 15 strains were further selected. All selected strains were subjected to a series of in vitro tests to assess their technological properties, including cell surface hydrophobicity (13.6-56.2%), autoaggregation ability (9.26-38.30%), coaggregation ability, and heat and lysozyme survival rates (84.74-94.01% and 80.52-99.37%, respectively). In vitro antagonism showed that Lb. plantarum (M5-19, M8-60, M8-59) exhibited the most strong inhibitory activity against 7 tested pathogens. Moreover, antibiotic resistance and hemolytic activity were investigated for safety assessment. No strain exhibited hemolytic activity, and most of the strains were sensitive to a series of 14 antibiotics of clinical importance. Ultimately, the principal component analysis of all data obtained above showed that 2 Lb. plantarum strains (M8-59, M8-60) and Lb. paracasei M1-36 exhibited the best potential for their inclusion as adjunct functional cultures in local fermented dairy products.

A clinical pilot study on the effect of the probiotic Lacticaseibacillus rhamnosus TOM 22.8 strain in women with vaginal dysbiosis

Lactobacilli with probiotic features play an essential role in maintaining a balanced vaginal microbiota and their administration has been suggested for the treatment and prevention of vaginal dysbiosis. The present study was aimed to in vitro and in vivo investigate the probiotic potential of the Lacticaseibacillus rhamnosus TOM 22.8 strain, isolated from the vaginal ecosystem of a healthy woman. For this purpose, safety and functional properties were in depth evaluated. The strain exhibited a broad spectrum of antagonistic activity against vaginal pathogens; adhesion capacity to both the vaginal VK2/E6E7 and the intestinal Caco-2 cells; anti-inflammatory and antioxidant activities, suggesting its promising probiotic features. In addition, an in vivo pilot-study was planned. Based on both clinical and microbiological parameters, the oral or vaginal strain administration, determined a significant pathogens reduction after 10 days of administration and a maintenance of eubiosis up to 30 days after the end of the treatment. Therefore, the L. rhamnosus TOM 22.8 strain can be proposed as valuable oral and/or vaginal treatment for vaginal dysbiosis.

Isolation and Genetic Identification of Endophytic Lactic Acid Bacteria From the Amazonian Açai Fruits: Probiotics Features of Selected Strains and Their Potential to Inhibit Pathogens

The açai palm (Euterpe oleracea) is native to the Amazon basin, a humid tropical forest. High levels of total mesophilic bacteria with high diversity have been consistently reported in açai fruits. As local consumers have few digestive problems, the results of the present study reveal the lactic acid bacteria (LAB) recovered from açai fruits with characteristics that suggest they are possible candidates for probiotics and antagonistic potential against pathogens for the first time. Açai fruits were sampled from five different locations in the Eastern Amazonia floodplains. Sixty-six isolates were recovered from fruits and tested for some probiotic characteristics following FAO/WHO guidelines. Approximately 65% of the isolates showed no catalase or oxidase activity, Gram-positive staining or cocci and bacilli cell morphology. Furthermore, 48% of the isolates demonstrated preliminary characteristics that suggest safety for use, as they presented no coagulase enzyme activity or gamma-hemolysis. These strains were identified as belonging to the genera Lactiplantibacillus and Pediococcus, and 32 strains also presented resistance to vancomycin, ciprofloxacin and streptomycin. In addition, 28 isolates showed a survival rate, expressed as log cycle reduction, higher than 0.9 under gastric conditions (pH 2). All strains tested positive in bile salts deconjugation tests and showed a survival rate higher than 0.8 in the presence of this salt. Regarding antimicrobial activity against pathogens, all strains were able to inhibit Salmonella Typhimurium (ATCC^® 14028^TM) and 97% were capable of inhibiting Escherichia coli (ATCC^® 25922^TM). Concerning the results of in vitro antagonistic assays, three isolates (B125, B135, and Z183 strains) were selected for antagonistic tests using açai juice contaminated with these two pathogens. All tested LAB strains were able to inhibit pathogen growth in açai juice. In summary, açai fruits are a potential source of LAB isolates to be investigated as probiotics.

Identification and probiotic potential of lactic acid bacteria from camel milk

In the present study, a total of 80 presumed lactic acid bacteria (LAB) were isolated from camel milk. Selected LAB were identified as Lactococcus lactis (cam 12), Enterococcus lactis (cam 14) and Lactobacillus plantarum (cam 15) and their potential were tested by tolerance & de-conjugation of bile salts, antimicrobial activity, surface hydrophobicity and adhesion potential) along with this of probiotics were evaluated for curd formation and assessed for sensory properties and syneresis. Selected LABs showed antimicrobial activity against wide range of pathogenic bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus and Escherchiaia. coli). LAB (cam 12, cam 14 and cam15) were highly sceptible to chloramphenicol, vancomycin, and tetracyclin. In vitro adhesion studies with Caco-2 cells demonstrated strong adhesion activity with hydrophobicity (99%) was observed. Acute oral toxicity of E. lactis and L. plantarum showed non-toxic, non-virulent and safe for industrial application. The study provides potential LAB which may act as a substitute of functional food, synthetic feed and industrial curd formulation with in the shortest span (240 min at 28–32 °C).

Evaluation of Biological, Textural, and Physicochemical Parameters of Panela Cheese Added with Probiotics

Biological, physicochemical and textural parameters of a Panela cheese with and without probiotics (LSB-c and C-c) were analyzed during 15 days of storage at 4 °C. Changes in cohesiveness, hardness, springiness, and chewiness were measured by texture profile analysis. Additionally, moisture, pH, nitrogenous fractions (nitrogen soluble in pH 4.6, non-protein nitrogen, 70% ethanol-soluble nitrogen, and water-soluble extract) were evaluated. The peptide profile of nitrogenous fractions was also analyzed. Finally, biological activity was evaluated by ABTS (2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) and DPPH (2,2-diphenyl-1-picrylhydrazyl), as well as the Inhibition of Angiotensin-Converting Enzyme. Analysis of variance showed significant differences for most of the evaluated parameters. By principal component analysis (PCA), two groups were separated, one corresponding to LSB-c and the other corresponding to C-c. The separation was given mostly by hardness, chewiness, and ABTS of all nitrogenous fractions. LSB-c showed higher biological activities than C-c.

Complete Genome Sequence of Lactobacillus hilgardii LMG 7934, Carrying the Gene Encoding for the Novel PII-Like Protein PotN

Lactic acid bacteria are widespread in various ecological niches with the excess of nutrients and have reduced capabilities to adapt to starvation. Among more than 280 Lactobacillus species known to the date, only five, including Lactobacillus hilgardii, carry in their genome the gene encoding for PII-like protein, one of the central regulators of cellular metabolism generally responding to energy- and carbon-nitrogen status in many free-living Bacteria, Archaea and in plant chloroplasts. In contrast to the classical PII encoding genes, in L. hilgardii genome the gene for PII homologue is located within the potABCD operon, encoding the ABC transporter for polyamines. Based on the unique genetic context and low sequence identity with genes of any other so-far characterized PII subfamilies, we termed this gene potN (Pot-protein, Nucleotide-binding). The second specific feature of L. hilgardii genome is that many genes encoding the proteins with similar function are present in two copies, while with low mutual identity. Thus, L. hilgardii LMG 7934 genome carries two genes of glutamine synthetase with 55% identity. One gene is located within classical glnRA operon with the gene of GlnR-like transcriptional regulator, while the second is monocistronic. Together with the relative large genome of L. hilgardii as compared to other Lactobacilli (2.771.862 bp vs ~ 2.2 Mbp in median), these data suggest significant re-arrangements of the genome and a wider range of adaptive capabilities of L. hilgardii in comparison to other bacteria of the genus Lactobacillus.

Evaluation of bacterial communities of Grana Padano cheese by DNA metabarcoding and DNA fingerprinting analysis

The composition of the bacterial community of Grana Padano (GP) cheese was evaluated by an amplicon-based metagenomic approach (DNA metabarcoding) and RAPD-PCR fingerprinting. One hundred eighteen cheeses, which included 118 dairies located in the production area of GP, were collected. Two hundred fifty-four OTUs were detected, of which 82 were further discriminated between dominant (32 OTUs; > 1% total reads) and subdominant (50 OTUs; between 0.1% and 1% total reads) taxa. Lactobacillus (L.) delbrueckii, Lacticaseibacillus (Lact.) rhamnosus, Lact. casei, Limosilactobacillus fermentum, Lactococcus (Lc.) raffinolactis, L. helveticus, Streptococcus thermophilus, and Lc. lactis were the major dominant taxa ('core microbiota'). The origin of samples significantly impacted on both richness, evenness, and the relative abundance of bacterial species, with peculiar pattern distribution among the five GP production regions. A differential analysis allowed to find bacterial species significantly associated with specific region pairings. The analysis of pattern similarity among RAPD-PCR profiles highlighted the presence of a 'core' community banding pattern present in all the GP samples, which was strictly associated with the core microbiota highlighted by DNA metabarcoding. A trend to group samples according to the five production regions was also observed. This study widened our knowledge on the bacterial composition and ecology of Grana Padano cheese.

Bio-functional properties of probiotic Lactobacillus: current applications and research perspectives

Lactic acid bacteria as a starter culture are very important component in the fermentation process of dairy and food industry. Application of lactic acid bacteria as probiotic bacteria adds more functionality to the developed product. Gut colonizing bacteria have attractive benefits related to human health. Bio-functional properties such as antimicrobial activity, anti-inflammatory, ACE-inhibitory, antioxidant, antidiarrheal, antiviral, immunomodulatory, hypocholesterolemic, anti-diabetic and anti-cancer activities are the most applicable research areas of lactic acid bacteria. Different strains of Lactobacillus are generally consumed as probiotics and colonize the gastrointestinal tract. Sometimes these bacteria may possess antimicrobial activity and may positively influence the effect of antibiotics. Use of Lactobacillus spp. for the development of functional foods is one of the promising areas of current research and applications. Individual bacterial species have unique biological activity, which may vary from strains to strains and identification of this uniqueness could be helpful in the development of functional and therapeutic food products.

Histamine and cholesterol lowering abilities of lactic acid bacteria isolated from artisanal Pico cheese

AIMS

This study was designed to select lactic acid bacteria with histamine- and cholesterol-reducing abilities to be used as potential probiotics.

METHODS AND RESULTS

Thirty strains of lactic acid bacteria isolated from an artisanal raw milk cheese were screened for their abilities to degrade histamine, reduce cholesterol and hydrolyse bile salts. Strains were also screened for safety and probiotic traits, such as resistance to gastrointestinal conditions, adhesion to Caco-2 cells, resistance to antibiotics and presence of virulence genes. Two Lactobacillus paracasei strains presented high cholesterol- and histamine-lowering abilities, tested negative for the presence of virulence genes and showed susceptibility to most important antibiotics. These strains were also shown to possess desirable in vitro probiotic properties, revealed by tolerance to gastrointestinal conditions and high adhesion to intestinal cells.

CONCLUSIONS

Among the screened strains, Lb. paracasei L3C21M6 revealed the best cholesterol and histamine reducing abilities together with desirable probiotic and safety features to be used in food applications.

SIGNIFICANCE AND IMPACT OF THE STUDY

The strain L3C21M6 is a good candidate for use as a probiotic with histamine-degrading activity and cholesterol lowering effect. In addition, this strain could be use in dairy foods to prevent histamine food poisoning.

Cultivable non-starter lactobacilli from ripened Parmigiano Reggiano cheeses with different salt content and their potential to release anti-hypertensive peptides

The impact of salt and fat intake on human health drives the consumer's attention towards dairy food with reduced salt and fat contents. How changes in salt and fat content modulate dairy LAB population and the associated proteolytic activities have been poorly studied. Here, non-starter LAB populations from 12 Parmigiano Reggiano (PR) cheeses (12-month ripened), clustered in low salt and fat content (LL-PR) and high salt and fat content (HH-PR) groups, were investigated and identified at specie-level with molecular assays. Lactobacillus rhamnosus was dominant in HH-PR samples, whereas Lactobacillus paracasei in LL-PR samples. (GTG)₅ rep-PCR analysis discriminated 11 and 12 biotypes for L. rhamnosus and L. paracasei isolates, respectively. Screening for proteolytic activity identified L. rhamnosus strains more proteolytic than L. paracasei, and, within L. rhamnosus species, HH-PR strains were generally more proteolytic than LL-PR strains. Two L. rhamnosus representatives, namely strain 0503 from LL-PR and strain 2006 from HH-PR, were functionally characterized in cow milk fermentation assay. HH-PR strain 2006 overcame LL-PR strain 0503 in acidification performance, leading to a fermented milk with higher angiotensin I-converting enzyme inhibitory and antioxidant activities. L. rhamnosus 2006 was more prone to release VPP, while L. rhamnosus 0503 released higher amount of IPP. This study provides evidences that salt/fat content affects NSLAB cultivable fraction and the associated proteolytic ability resulting in a complex occurrence of bioactive peptides featuring health-promoting properties.