Lactic acid bacteria of foods and their current taxonomy

The ruminant gut microbiome vs enteric methane emission: The essential microbes may help to mitigate the global methane crisis

Ruminants release enteric methane into the atmosphere, significantly increasing greenhouse gas emissions and degrading the environment. A common focus of traditional mitigation efforts is on dietary management and manipulation, which may have limits in sustainability and efficacy, exploring the potential of essential microorganisms as a novel way to reduce intestinal methane emissions in ruminants; a topic that has garnered increased attention in recent years. Fermentation and feed digestion are significantly aided by essential microbes found in the rumen, such as bacteria, fungi, and archaea. The practical implications of the findings reported in various studies conducted on rumen gut concerning methane emissions may pave the way to understanding the mechanisms of CH4 production in the rumen to enhance cattle feed efficiency and mitigate CH4 emissions from livestock. This review discussed using essential bacteria to reduce intestinal methane emissions in ruminants. It investigates how particular microbial strains or consortia can alter rumen fermentation pathways to lower methane output while preserving the health and productivity of animals. We also describe the role of probiotics and prebiotics in managing methane emissions using microbial feed additives, some recent studies involving microbial interventions have been discussed. The use of new methods involving functional metagenomics and meta-transcriptomics for exploring the rumen microbiome structure has been highlighted. This review also emphasizes the challenges faced in altering the gut microbiome and future directions in this area.

Roles of flavoprotein oxidase and the exogenous heme- and quinone-dependent respiratory chain in lactic acid bacteria

Lactic acid bacteria (LAB) are a type of bacteria that convert carbohydrates into lactate through fermentation metabolism. While LAB mainly acquire energy through this anaerobic process, they also have oxygen-consuming systems, one of which is flavoprotein oxidase and the other is exogenous heme- or heme- and quinone-dependent respiratory metabolism. Over the past two decades, research has contributed to the understanding of the roles of these oxidase machineries, confirming their suspected roles and uncovering novel functions. This review presents the roles of these oxidase machineries, which are anticipated to be critical for the future applications of LAB in industry and comprehending the virulence of pathogenic streptococci.

Iron-tannic acid nano-coating: A promising treatment approach for enhancing Lactococcus lactis antibiotic resistance

The objective of this study was to explore a novel methodology for the synthesis of nanocoated probiotics following their collection and cultivation under optimized conditions, in light of their significant contribution to human health. Probiotics are instrumental in sustaining immune health by modulating the gastrointestinal microbiota and facilitating digestion. However, the equilibrium they maintain can be adversely affected by antibiotic treatments. It is critical to investigate the vulnerability of probiotics to antibiotics, considering the potential implications. This research aimed to assess whether nanoparticle coating could augment the probiotics' resistance to antibiotic influence. A strain of Lactococcus lactis (L. lactis) was isolated, cultured, and comprehensively characterized utilizing state-of-the-art methodologies, including the VITEK® 2 compact system, VITEK® MS, and 16S rRNA gene sequencing. The nanoparticle coating was performed using iron (III) chloride hexahydrate and tannic acid, followed by an evaluation of the probiotics' resistance to a range of antibiotics. The analysis through scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrated a partial nanoparticle coating of the probiotics, which was further supported by UV/Vis spectroscopy findings, suggesting enhanced resistance to standard antibiotics. The results revealed that this strain possesses a unique protein profile and is genetically similar to strains identified in various other countries. Moreover, nano-encapsulation notably increased the strain's resistance to a spectrum of standard antibiotics, including Benzylpenicillin, Teicoplanin, Oxacillin, Vancomycin, Tetracycline, Rifampicin, Erythromycin, and Clindamycin. These findings imply that nanoparticle-coated probiotics may effectively counteract the detrimental effects of extended antibiotic therapy, thus preserving their viability and beneficial influence on gastrointestinal health.

Physicochemical and structural characterisation of a branched dextran type exopolysaccharide (EPS) from Weissella confusa S6 isolated from fermented sausage (Sucuk)

Exopolysaccharide (EPS) producing Lactic Acid Bacteria (LAB) species can be presented in distinct environments. In this study, Turkish fermented sausage (sucuk) was tested for the presence of EPS producer LAB strains and slimy-mucoid colonies were selected for further tests. Among the isolates, Weissella confusa strain S6 was identified and tested for the physicochemical characterisation of its EPS. This strain was found to produce 0.74 g L-1 of EPS in modified BHI medium conditions. Structural characterisation of EPS S6 by 1H and 13C NMR demonstrated that EPS S6 was a highly branched dextran type glucan formed by mainly (1 → 2)-linked α-d-glucose units together with low levels of (1 → 3)-linked α-d-glucose units as branching points. This structure was further confirmed by methylation analysis detected by GC-MS. An average molecular weight of 8 × 106 Da was detected for dextran S6. The FTIR analysis supported the dextran structure and revealed the presence of distinct functional groups within dextran S6 structure. A strong thermal profile was observed for dextran S6 detected by DSC and TGA analysis and dextran S6 revealed a degradation temperature of 289 °C. In terms of physical status, dextran S6 showed amorphous nature detected by XRD analysis. SEM analysis of dextran S6 demonstrated its rough, compact and porous morphology whereas AFM analysis of dextran S6 detected in its water solution showed the irregularity with no clear cross-link within the dextran chains. These technological features of dextran S6 suggests its potential to be used for in situ or ex situ application during meat fermentations.

Lactococcus lactis as an Interleukin Delivery System for Prophylaxis and Treatment of Inflammatory and Autoimmune Diseases

Target delivery of therapeutic agents with anti-inflammatory properties using probiotics as delivery and recombinant protein expression vehicles is a promising approach for the prevention and treatment of many diseases, such as cancer and intestinal immune disorders. Lactococcus lactis, a Lactic Acid Bacteria (LAB) widely used in the dairy industry, is one of the most important microorganisms with GRAS status for human consumption, for which biotechnological tools have already been developed to express and deliver recombinant biomolecules with anti-inflammatory properties. Cytokines, for  example, are immune system communication molecules present at virtually all levels of the immune response. They are essential in cellular and humoral processes, such as hampering inflammation or adjuvating in the adaptive immune response, making them good candidates for therapeutic approaches. This review discusses the advances in the development of new therapies and prophylactic approaches using LAB to deliver/express cytokines for the treatment of inflammatory and autoimmune diseases in the future.

Sodium carboxymethyl celluloses as a cryoprotectant for survival improvement of lactic acid bacterial strains subjected to freeze-drying

This study investigated the possibility of sodium carboxymethyl celluloses (Na-CMC) in protecting the viability of lactic acid bacteria (LAB) against freeze-drying stress. 1 % concentration of Na-CMC with a 0.7 substitution degree and viscosity of 1500 to 3100 (MPa.s) was found to protect Lactobacillus delbrueckii subsp. bulgaricus CICC 6098 best, giving a high survival rate of 23.19 ± 0.88 %, high key enzymatic activities, and 28-day storage stability. Additionally, Na-CMC as cryoprotectant provided good protection for other 7 lactic acid bacterial strains subjected to freeze-drying. The highest survival rate was 48.79 ± 0.20 U/mg for β-GAL, 2.75 ± 0.15 U/mg for Na+-K+-ATPase, and 2.73 ± 0.41 U/mg for Ca2+-Mg2+-ATPase as 48.48 ± 0.46 % for freeze-dried Pediococcus pentosaceus CICC 22228. It was Interesting to note that the presence of Na-CMC reduced the freezable water content of the lyophilized powders containing the tested strains through its hydroxyl group, and supplied micro-holes and fibers for protecting the integrated structure of LAB cell membrane and wall against the freezing damage. It is clear that addition of Na-CMC should be promising as a new cryoprotective agent available for processing the lyophilized stater cultures of LAB strains.

Biopreservation of Fresh Sardines (Sardina pilchardus) Using Lactiplantibacillus plantarum OV50 Isolated from Traditional Algerian Green Olives Preparations

Lactiplantibacillus plantarum OV50 is a novel strain that was isolated from Algerian olives. Prior to its use as a natural biopreservative, OV50 underwent characterization for various functions. OV50 shows no proteolytic, lipolytic, or hemolytic activity. In addition, it is non-cytotoxic to eukaryotic cells and does not exhibit acquired antibiotic resistance. OV50 was tested with Pseudomonas aeruginosa ATCC 27835, Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, and Vibrio cholerae ATCC 14035 in a sardine based-medium at 37 °C and 7 °C. At 37 °C, OV50 completely inhibited the growth of these foodborne pathogens for a maximum of 6 h. At 7 °C, it suppressed their growth for a maximum of 8 days, except for S. aureus ATCC 6538, whose growth was reduced from 4 to 2 log CFU/mL. Microbiological counts, total volatile basic nitrogen (TVB-N), and peroxide values (PV) concentrations were determined in fresh sardines inoculated with OV50 and kept at 7 °C for 12 days. The inoculated sardines showed a significant reduction in TVB-N levels at D8 (34.9 mg/100 g) compared to the control (59.73 mg/100 g) and in PV concentrations at D4 (6.67 meq/kg) compared to the control (11.44 meq/kg), as well as a significant reduction in the numbers of Enterobacterales, Coliforms, Pseudomonas spp., Vibrio spp., and S. aureus At D8 and D12 compared to the control. Taken together, these results indicate that OV50 can improve the microbiological safety, freshness, and quality of sardines.

Leuconostoc citreum: A Promising Sourdough Fermenting Starter for Low-Sugar-Content Baked Goods

This review highlights Leuconostoc citreum's promising possibilities as a proficient mannitol producer and its potential implications for sugar reduction, with a focus on its use in sourdough-based baked good products. Mannitol, a naturally occurring sugar alcohol, has gained popularity in food items due to its low calorie content and unique beneficial qualities. This study summarizes recent research findings and investigates the metabolic pathways and culture conditions that favor increased mannitol production by Leuconostoc citreum. Furthermore, it investigates the several applications of mannitol in baked goods, such as its function in increasing texture, flavor and shelf life while lowering the sugar content. Sourdough-based products provide an attractive niche for mannitol integration, as customer demand for healthier and reduced-sugar options increases.

Diagnostic and therapeutic value of EVs in lungs diseases and inflammation

Extracellular vesicles (EVs) are membrane-derived messengers which have been playing an important role in the inflammation and pathogenesis of lung diseases. EVs contain varieties of DNA, RNA, and membrane receptors through which they work as a delivery system for bioactive molecules as well as intracellular communicators. EV signaling mediates tumor progression and metastasis. EVs are linked with many diseases and perform a diagnostic role in lung injury and inflammation so are used to diagnose the severity of diseases. EVs containing a variety of biomolecules communicate with the recipient cells during pathophysiological mechanisms thereby acquiring the attention of clinicians toward the diagnostic and therapeutic potential of EVs in different lung diseases. In this review, we summarize the role of EVs in inflammation with an emphasis on their potential as a novel candidate in the diagnostics and therapeutics of chronic obstructive pulmonary disease, asthma, and sarcoidosis.

Shelf-life studies of putative probiotic Lacticaseibacillus casei strains in milk and model yogurt

Lacticaseibacillus casei are commonly utilized as probiotic in a wide-range of fermented and unfermented dairy products. The stability of probiotics in fermented dairy products during shelf-life is of concern due to low pH and high level of organic acids. The objective of this study is to evaluate L. casei for their ability to survive in a model yogurt and fluid milk; additionally, their impact on the pH, organic acids, and sensory attributes of these products was examined. The strain-to-strain differences in cell densities in yogurt and milk inoculated at a therapeutic level at the end of shelf-life were 1.2 and 1.4 log CFU/mL, respectively. Five of the strains examined increased the pH of the yogurt, while two strains were observed to reduce the pH. In milk, one strain raised the pH, while eleven strains reduced the pH. The levels of lactate, acetate, and formate in both the yogurt and milk were altered in a strain-specific manner. The results suggested that the metabolism by these strains differed significantly during the shelf-life. Careful strain selection is required to identify probiotic L. casei strains that will survive through shelf-life in either yogurt or fluid milk and not impact product quality.

Selection and Characterization of Bacteriocinogenic Lactic Acid Bacteria from the Intestine of Gilthead Seabream (Sparus aurata) and Whiting Fish (Merlangius merlangus): Promising Strains for Aquaculture Probiotic and Food Bio-Preservation

This study sought to evaluate the probiotic properties and the food preservation ability of lactic acid bacteria isolates collected from the intestines of wild marine fishes (gilthead seabream (Sparus aurata) (n = 60) and whiting fish (Merlangius merlangus) (n = 40)) from the Mediterranean sea in the area of Mostaganem city, Algeria. Forty-two isolates were identified as: Enterococcus durans (n = 19), Enterococcus faecium (n = 15), Enterococcus faecalis (n = 4), Lactococcus lactis subp. lactis (n = 3), and Lactobacillus plantarum (n = 1). All isolates showed inhibition to at least one indicator strain, especially against Listeria monocytogenes, Staphylococcus aureus, Paenibacillus larvae, Vibrio alginolyticus, Enterococcus faecalis, Bacillus cereus, and Bacillus subtilis. In all collected isolates, PCR analysis of enterocin-encoding genes showed the following genes: entP (n = 21), ent1071A/B (n = 11), entB (n = 8), entL50A/B (n = 7), entAS48 (n = 5), and entX (n = 1). Interestingly, 15 isolates harbored more than one ent gene. Antimicrobial susceptibility, phenotypic virulence, and genes encoding virulence factors were investigated by PCR. Resistance to tetracycline (n = 8: tetL + tetK), erythromycin (n = 7: 5 ermA, 2 msrA, and 1 mef(A/E)), ciprofloxacin (n = 1), gentamicin (n = 1: aac(6')-aph(2″)), and linezolid (n = 1) were observed. Three isolates were gelatinase producers and eight were α-hemolytic. Three E. durans and one E. faecium harbored the hyl gene. Eight isolates showing safety properties (susceptible to clinically relevant antibiotics, free of genes encoding virulence factors) were tested to select probiotic candidates. They showed high tolerance to low pH and bile salt, hydrophobicity power, and co-culture ability. The eight isolates showed important phenotypic and genotypic traits enabling them to be promising probiotic candidates or food bio-conservers and starter cultures.

Optimal preparation of food waste to increase its utility for sophorolipid production by Starmerella bombicola

Secondary feedstocks, such as food waste (FW), have been used for yeasts (e.g. Starmerella bombicola) to produce sophorolipids (SLs), which are commercially available biosurfactants. However, the quality of FW varies by location and season and may contains chemicals that inhibit SLs production. Therefore, it is crucial to identify such inhibitors and, if possible, remove them, to ensure efficient utilization. In this study, large scale FW was first analysed to determine the concentration of potential inhibitors. Lacticacid, acetic acid and ethanol were identified and found to be inhibitors of the growth of S. bombicola and its SLs production. Various methods were then evaluated for their ability to remove these inhibitors. Finally, a simple and effective strategy for removing inhibitors from FW was developed that complied with the 12 principles of green chemistry and could be adopted by industry for high SLs production.

Immunomodulatory effects of different strains of Lactococcus lactis in DSS-induced colitis

Inflammatory bowel diseases (IBD) are gastrointestinal disorders characterized by a breakdown in intestinal homeostasis by inflammatory immune responses to luminal antigens. Novel strategies for ameliorating IBD have been proposed in many studies using animal models. Our group has demonstrated that administration of Lactococcus lactis NCDO 2118 can improve clinical parameters of colitis induced by oral administration of dextran sulphate sodium (DSS). However, it is not clear whether other strains of L. lactis can yield the same effect. The objective of present study was to analyze the effects of three different L. lactis strains (NCDO2118, IL1403 and MG1363) in the development of DSS-induced colitis in C57BL/6 mice. Acute colitis was induced in C57/BL6 mice by the administration of 2% DSS during 7 consecutive days. Body weight loss and shortening of colon length were observed in DSS-treated mice, and none of L. lactis strains had an impact in these clinical signs of colitis. On the other hand, all strains improved the global macroscopical disease index and prevented goblet cells depletion as well as the increase of intestinal permeability. TNF-α production was reduced in gut mucosa of L. lactis DSS-treated mice indicating a modulation of a critical pro-inflammatory response by all strains tested. However, only L. lactis NCDO2118 and MG1363 induced a higher frequency of CD11c+CD11b-CD103+ tolerogenic dendritic cells in lymphoid organs of mice at steady state. We conclude that all tested strains of L. lactis improved the clinical scores and parameters of colitis, which confirm their anti-inflammatory properties in this model of colitis.

Genomic, metabolomic, and functional characterisation of beneficial properties of Pediococcus pentosaceus ST58, isolated from human oral cavity

Bacteriocins produced by lactic acid bacteria are proteinaceous antibacterial metabolites that normally exhibit bactericidal or bacteriostatic activity against genetically closely related bacteria. In this work, the bacteriocinogenic potential of Pediococcus pentosaceus strain ST58, isolated from oral cavity of a healthy volunteer was evaluated. To better understand the biological role of this strain, its technological and safety traits were deeply investigated through a combined approach considering physiological, metabolomic and genomic properties. Three out of 14 colonies generating inhibition zones were confirmed to be bacteriocin producers and, according to repPCR and RAPD-PCR, differentiation assays, and 16S rRNA sequencing it was confirmed to be replicates of the same strain, identified as P. pentosaceus, named ST58. Based on multiple isolation of the same strain (P. pentosaceus ST58) over the 26 weeks in screening process for the potential bacteriocinogenic strains from the oral cavity of the same volunteer, strain ST58 can be considered a persistent component of oral cavity microbiota. Genomic analysis of P. pentosaceus ST58 revealed the presence of operons encoding for bacteriocins pediocin PA-1 and penocin A. The produced bacteriocin(s) inhibited the growth of Listeria monocytogenes, Enterococcus spp. and some Lactobacillus spp. used to determine the activity spectrum. The highest levels of production (6400 AU/ml) were recorded against L. monocytogenes strains after 24 h of incubation and the antimicrobial activity was inhibited after treatment of the cell-free supernatants with proteolytic enzymes. Noteworthy, P. pentosaceus ST58 also presented antifungal activity and key metabolites potentially involved in these properties were identified. Overall, this strain can be of great biotechnological interest towards the development of effective bio-preservation cultures as well as potential health promoting microbes.

Targeting NAD+ regeneration enhances antibiotic susceptibility of Streptococcus pneumoniae during invasive disease

Anaerobic bacteria are responsible for half of all pulmonary infections. One such pathogen is Streptococcus pneumoniae (Spn), a leading cause of community-acquired pneumonia, bacteremia/sepsis, and meningitis. Using a panel of isogenic mutants deficient in lactate, acetyl-CoA, and ethanol fermentation, as well as pharmacological inhibition, we observed that NAD(H) redox balance during fermentation was vital for Spn energy generation, capsule production, and in vivo fitness. Redox balance disruption in fermentation pathway-specific fashion substantially enhanced susceptibility to killing in antimicrobial class-specific manner. Blocking of alcohol dehydrogenase activity with 4-methylpyrazole (fomepizole), an FDA-approved drug used as an antidote for toxic alcohol ingestion, enhanced susceptibility of multidrug-resistant Spn to erythromycin and reduced bacterial burden in the lungs of mice with pneumonia and prevented the development of invasive disease. Our results indicate fermentation enzymes are de novo targets for antibiotic development and a novel strategy to combat multidrug-resistant pathogens.

Effects of Lactobacillus plantarum and its Fermentation Products on Growth Performance, Immune Function, Intestinal pH and Cecal Microorganisms of Lingnan Yellow Chicken

The present research was conducted to investigate the effects of dietary supplementation of Lactobacillus plantarum and its fermentation products on growth performance, specific immune function, intestinal pH, and cecal microorganisms in yellow-feather broilers. A total of 1,200 yellow-feather broilers of similar weight and good health condition at 1 d of age were selected and randomly divided into 5 groups. The CK group was fed the basal diet, and the experimental group (I, II, III, IV) were supplemented with 0.1, 0.15% L. plantarum and 3, 4% L. plantarum fermentation products. The results showed that each treatment could improve the growth performance (P < 0.05) and feed conversion rate of yellow-feather broilers. Besides, the pH value of the gastrointestinal tract of yellow-feather broilers (P < 0.05) was significantly reduced through the use of L. plantarum and its fermentation products as additives, which also facilitated the animals to regulate the balance of cecal microorganisms. The immune function assay showed that the bursal index (P < 0.05), spleen index (P < 0.05), and the content of serum immunoglobulins IgA and IgG (P < 0.05) were significantly increased in yellow-finned broilers aged 1 to 21 d by supplementing the diet with L. plantarum. In conclusion, adding L. plantarum or its fermentation products to the diet can improve the growth performance of yellow-feather broilers, and the direct addition of L. plantarum is better than adding fermentation products.

Microbial growth kinetics as a method to model and predict the development of starter cultures

A comparative study was conducted on the growth rate of lactic acid bacteria involved in starter cultures for the production of lactic acid products. Based on the data obtained, with respect to the rate of development, it is possible to predict their development as monocultures or as cultures in symbiotic relationship. In order to achieve the set objective, culture of lactic acid microorganisms was carried out in a bioreactor for 24 hours. Data on the rate of development in the different phases, represented by the acid formation curve, are reported for the following strains: Lactobacillus delbrueckii ssp. bulgaricus S22; Streptococcus thermophilus S1; Lacticaseibacillus casei ssp. rhamnosus AS15; Lactobacillus casei ssp. shirota 51C. The conclusions drawn allow the correct and predictable use of the investigated strains of lactic acid bacteria in starter cultures for the production of lactic acid products.

Lactic Acid Bacteria: A Promising Tool for Menopausal Health Management in Women

Menopause is a period during which women undergo dramatic hormonal changes. These changes lead to physical and mental discomfort, are greatly afflictive, and critically affect women's lives. However, the current safe and effective management measures for women undergoing menopause are insufficient. Several probiotic functions of lactic acid bacteria (LAB) have been recognized, including alleviation of lactose intolerance, protection of digestive tract health, activation of the immune system, protection against infections, improvement of nutrient uptake, and improvement of the microbiota. In this review, we highlight the currently available knowledge of the potential protective effects of LAB on preventing or mitigating menopausal symptoms, particularly in terms of maintaining balance in the vaginal microbiota, reducing bone loss, and regulating the nervous system and lipid metabolism. Given the increasing number of women entering menopause and the emphasis on the management of menopausal symptoms, LAB are likely to soon become an indispensable part of clinical/daily care for menopausal women. Herein, we do not intend to provide a comprehensive analysis of each menopausal disorder or to specifically judge the reliability and safety of complementary therapies; rather, we aim to highlight the potential roles of LAB in individualized treatment strategies for the clinical management of menopause.

Fermented Minor Grain Foods: Classification, Functional Components, and Probiotic Potential

Fermented minor grain (MG) foods often have unique nutritional value and functional characteristics, which are important for developing dietary culture worldwide. As a kind of special raw material in fermented food, minor grains have special functional components, such as trace elements, dietary fiber, and polyphenols. Fermented MG foods have excellent nutrients, phytochemicals, and bioactive compounds and are consumed as a rich source of probiotic microbes. Thus, the purpose of this review is to introduce the latest progress in research related to the fermentation products of MGs. Specific discussion is focused on the classification of fermented MG foods and their nutritional and health implications, including studies of microbial diversity, functional components, and probiotic potential. Furthermore, this review discusses how mixed fermentation of grain mixtures is a better method for developing new functional foods to increase the nutritional value of meals based on cereals and legumes in terms of dietary protein and micronutrients.

Lactic Acid Bacteria (LAB): Autochthonous and Probiotic Microbes for Meat Preservation and Fortification

The enhanced concern of the consumers regarding the safety, quality of the food products, and avoidance of the use of chemical food preservatives has resulted in a breakthrough in biopreservation. This has resulted in the use of beneficial microbial species, including bacteria and their secondary metabolites, to enhance the shelf-life and quality of the food products. Meat preservation and fortification are among the biggest concerns, as they are relevant to the majority of food products. The chemical preservatives conventionally used in preserving meat and meat products possess several detrimental effects on the consumers. Thus, alternative strategies are needed to combat strategically in facilitating the shelf-life and quality. Lactic acid bacteria (LAB) are considered the safest organism and have a profound role in food and food-processing industries. The biofilm developed by the bacteria prevents the growth of various undesirable microorganisms on meat and meat products. Various studies depicted that LAB produces various antimicrobial metabolites that can act effectively on the food-degrading pathogens, rendering it safe and enhancing shelf-life. This review, thus, deals with the use of LAB as biopreservatives for enhancing the shelf-life of meat and meat products and helping its fortification.

Use of genetically modified lactic acid bacteria and bifidobacteria as live delivery vectors for human and animal health

There is now strong evidence to support the interest in using lactic acid bacteria (LAB)in particular, strains of lactococci and lactobacilli, as well as bifidobacteria, for the development of new live vectors for human and animal health purposes. LAB are Gram-positive bacteria that have been used for millennia in the production of fermented foods. In addition, numerous studies have shown that genetically modified LAB and bifodobacteria can induce a systemic and mucosal immune response against certain antigens when administered mucosally. They are therefore good candidates for the development of new mucosal delivery strategies and are attractive alternatives to vaccines based on attenuated pathogenic bacteria whose use presents health risks. This article reviews the most recent research and advances in the use of LAB and bifidobacteria as live delivery vectors for human and animal health.

Recent Progress in Electronic Noses for Fermented Foods and Beverages Applications

Fermented foods and beverages have become a part of daily diets in several societies around the world. Emitted volatile organic compounds play an important role in the determination of the chemical composition and other information of fermented foods and beverages. Electronic nose (E-nose) technologies enable non-destructive measurement and fast analysis, have low operating costs and simplicity, and have been employed for this purpose over the past decades. In this work, a comprehensive review of the recent progress in E-noses is presented according to the end products of the main fermentation types, including alcohol fermentation, lactic acid fermentation, acetic acid fermentation and alkaline fermentation. The benefits, research directions, limitations and challenges of current E-nose systems are investigated and highlighted for fermented foods and beverage applications.

Progressive dysbiosis of human orodigestive microbiota along the sequence of gastroesophageal reflux, Barrett's esophagus, and esophageal adenocarcinoma

The incidence of esophageal adenocarcinoma (EA) has drastically increased in the United States since 1970s for unclear reasons. We hypothesized that the widespread usage of antibiotics has increased the procarcinogenic potential of the orodigestive microbiota along the sequence of gastroesophageal reflux (GR), Barrett's esophagus (BE), and EA phenotypes. This case control study included normal controls (NC) and three disease phenotypes GR, BE, and EA. Microbiota in the mouth, esophagus, and stomach, and rectum were analyzed using 16S rRNA gene sequencing. Overall, we discovered 44 significant pairwise differences in abundance of microbial taxa between the four phenotypes, with 12 differences in the mouth, 21 in the esophagus, two in the stomach, and nine in the rectum. Along the GR→BE→EA sequence, oral and esophageal microbiota were more diversified, the dominant genus Streptococcus was progressively depleted while six other genera Atopobium, Actinomyces, Veillonella, Ralstonia, Burkholderia, and Lautropia progressively enriched. In NC, Streptococcus appeared to control populations of other genera in the foregut via numerous negative and positive connections, while in disease states, the rich network was markedly simplified. Inferred gene functional content showed a progressive enrichment through the stages of EA development in genes encoding antibiotic resistance, ligands of Toll-like and NOD-like receptors, nitrate-nitrite-nitric oxide pathway, and acetaldehyde metabolism. The orodigestive microbiota is in a progressive dysbiotic state along the GR-BE-EA sequence. The increasing dysbiosis and antibiotic and procarcinogenic genes in the disease states warrants further study to define their roles in EA pathogenesis. This article is protected by copyright. All rights reserved.

Antifungal Mechanisms and Application of Lactic Acid Bacteria in Bakery Products: A Review

Bakery products are nutritious, but they are susceptible to fungal contamination, which leads to a decline in quality and safety. Chemical preservatives are often used to extend the shelf-life of bakery products, but long-term consumption of these preservatives may increase the risk of chronic diseases. Consumers increasingly demand food with fewer chemical preservatives. The application of lactic acid bacteria (LAB) as a novel biological preservative not only prolongs the shelf-life of bakery products but also improves the baking properties of bakery products. This review summarizes different types and action mechanisms of antifungal compounds produced by LAB, factors affecting the production of antifungal compounds, and the effects of antifungal LAB on bakery products, providing a reference for future applications of antifungal LAB in bakery products.

Microbial Consortium Associated with Crustacean Shells Composting

Soil microbes play an essential role in the biodegradation of crustacean shells, which is the process of sustainable bioconversion to chitin derivatives ultimately resulting in the promotion of plant growth properties. While a number of microorganisms with chitinolytic properties have been characterized, little is known about the microbial taxa that participate in this process either by active chitin degradation or by facilitation of this activity through nutritional cooperation and composting with the chitinolytic microorganisms. In this study, we evaluated the transformation of the soil microbiome triggered by close approximation to the green crab shell surface. Our data indicate that the microbial community associated with green crab shell matter undergoes significant specialized changes, which was reflected in a decreased fungal and bacterial Shannon diversity and evenness and in a dramatic alteration in the community composition. The relative abundance of several bacterial and fungal genera including bacteria Flavobacterium, Clostridium, Pseudomonas, and Sanguibacter and fungi Mortierella, Mycochlamys, and Talaromyces were increased with approximation to the shell surface. Association with the shell triggered significant changes in microbial cooperation that incorporate microorganisms that were previously reported to be involved in chitin degradation as well as ones with no reported chitinolytic activity. Our study indicates that the biodegradation of crab shells in soil incorporates a consortium of microorganisms that might provide a more efficient way for bioconversion.

Bioprophylactic potential of novel human colostrum probiotics via apoptotic induction of colon cancer cells and cell immune activation

The potential and modes of action of novel human colostrum probiotics were investigated with the aim of studying their application as an alternative in the bioprophylactic and biotherapy of colon cancer. A total of 218 isolates of Gram-positive rod and cocci bacteria obtained from the colostrum of 50 healthy lactating females were collected. Beneficial probiotic criteria from these isolates, which included growth inhibition against seven foodborne pathogens (Helicobacter pylori, Escherichia coli, Salmonella Enteritidis, Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus and Listeria monocytogenes), no blood haemolysis and tolerance to acid and bile salt conditions, resulted in only eight probiotic bacteria successfully inhibiting the proliferation of colon cancer cells at rates of 32.47-61.21%. Two probiotic bacteria with higher anticancer efficacy (Streptococcus salivarius CP163 and S. salivarius CP208) were identified using 16S rRNA sequences. High rates of cell surface hydrophobicity, autoaggregation and coaggregation were obtained from both probiotics. The probiotic mode of action involved synergic probiotic adhesion to colon cancer cells that triggered SCFA bioproduction. Apoptotic induction of colon cancer cell death through caspase-2 activity, DNA fragmentation and morphological change as assessed by AO/PI staining were also observed. Immune stimulation by S. salivarius CP163 and S. salivarius CP208 resulted in B and T-cell lymphocyte activation. This study suggests that these novel human colostrum probiotics could be applied as a functional food to facilitate a bioprophylactic strategy in colon cancer.

Effect of phenyllactic acid on silage fermentation and bacterial community of reed canary grass on the Qinghai Tibetan Plateau

Background

This study aimed to investigate the effect of phenyllactic acid as an additive on silage fermentation and bacterial community of reed canary grass (RCG, Phalaris arundinacea L.) on the Qinghai Tibetan Plateau. At the heading stage, RCG was harvested, chopped and ensiled in small bag silos. The silage was treated without (control, 1.0 g/mL sterile water, on a fresh matter basis (FM)) or with phenyllactic acid (PLA, 3 mg/mL, FM), antimicrobial additive (PSB, a mixture of potassium sorbate and sodium benzoate, 2%, FM), lactic acid bacteria inoculant (LABi, L. plantarum + L. curvatus, 1 × 10⁶ cfu/g, FM) and PLA + LABi, and then stored in a dark room at the ambient temperature (5 ~ 15 °C) for 60 days.

Results

Compared with control, PLA decreased lactic acid, acetic acid and ammonia-N contents, and subsequently increased CP content of RCG silage. PLA enhanced the growth of lactic acid bacteria and reduced the count of yeasts (P < 0.05) in RCG silage, with reduced bacterial richness index (Chao1), observed operational taxonomic units and diversity index (Simpson). In relative to control, moreover, PLA and PLA + LABi increased the relative abundance of Lactococcus in RCG silage by 27.73 and 16.93%, respectively.

Conclusions

Therefore, phenyllactic acid at ensiling improved nutritional quality of RCG silage by advancing the disappearance of yeasts and the dominance of Lactococcus.

Effect of β-Estradiol on Mono- and Mixed-Species Biofilms of Human Commensal Bacteria Lactobacillus paracasei AK508 and Micrococcus luteus C01 on Different Model Surfaces

The impact of steroid hormones, and particularly estradiol, on human microbiota could be recognized as a substantial part of human-microbiota interactions. However, an area that remains poorly investigated is that of the skin and vaginal microbial communities and biofilms, which contain non-pathogenic bacteria of phyla Firmicutes and Actinobacteria, especially probiotic bacteria of the genus Lactobacillus and the widespread, safe skin genus, Micrococcus. Experiments with Lactobacillus paracasei AK508 and Micrococcus luteus C01 biofilms on PTFE cubes showed dose-dependent effects of estradiol at concentrations of 0.22 nM and 22 nM. The hormone mostly inhibits L. paracasei growth and stimulates M. luteus. The presented studies of colony-forming unit (CFU) amountsand cell aggregation in biofilms on glass fiber filters showed the same general tendencies. Estradiol generally increased the aggregation of cells in monospecies communities and potentially changed the synthesis of antibacterial metabolites in L. paracasei. The balance between two bacteria in mixed-species biofilms depended on the initial adhesion stage, and when this stage was reduced, micrococci were more resistant to the antagonistic action of L. paracasei. Moreover, in mixed-species biofilms, the effect of estradiol on lactobacilli altered from inhibition to stimulation, potentially due to the presence of M. luteus. At the same time, ethanol as a solvent for estradiol at the concentration 0.6% acted mostly as an antagonist of the hormone and had an opposite effect on bacteria; nevertheless, the overlapping of ethanol and estradiol effects was shown to be minimal. The data obtained prove the complexity of microbial interactions and the regulatory effect of estradiol on commensal bacteria biofilms.

Inhibitory Effect of Lactiplantibacillusplantarum and Lactococcus lactis Autochtonous Strains against Listeria monocytogenes in a Laboratory Cheese Model

In the present study, six Lactococcus lactis and seven Lactiplantibacillus plantarum strains isolated from artisanal Sardinian dairy products were evaluated for their efficacy in controlling the growth of Listeria monocytogenes during the storage of miniature fresh cheese manufactured on a laboratory scale to exploit their possible use as biopreservatives. The strains were tested for antimicrobial activity and some technological characteristics before using them in miniature fresh cheese to evaluate their in situ antilisterial effect. Our results showed that five strains (L. lactis 16FS16-9/20234-11FS16 and Lpb. plantarum 1/14537-4A/20045) could be considered suitable candidates for use as protective cultures in fresh cheese manufacture since they significantly lowered the pathogen counts by 3–4 log units compared to the control; however, all strains tested were capable of decreasing L. monocytogenes numbers. Our results suggest that the single and combined action of the acidifying power and the production of bacteriocin of these strains was capable of controlling and/or reducing the growth of L. monocytogenes. Considering their technological characteristics, they might be used as starter/adjunct cultures to increase the safety of the products, perhaps in association with other antimicrobial hurdles.

Vaccination in Leishmaniasis: A Review Article

Leishmaniasis is caused by protozoan Leishmania parasites that are transmitted through female sandfly bites. The disease is predominantly endemic to the tropics and semi-tropics and has been reported in more than 98 countries. Due to the side effects of anti-Leishmania drugs and the emergence of drug-resistant isolates, there is currently no encouraging prospect of introducing an effective therapy for the disease. Hence, it seems that the key to disease control management is the introduction of an effective vaccine, particularly against its cutaneous form. Advances in understanding underlying immune mechanisms are feasibale using a variety of candidate antigens, including attenuated live parasites, crude antigens, pure or recombinant Leishmania proteins, Leishmania genes encoding protective proteins, as well as immune system activators from the saliva of parasite vectors. However, there is still no vaccine against different types of human leishmaniasis. In this study, we review the works conducted or being performed in this field.

Effect of genus Clostridium abundance on mixed-culture fermentation converting food waste into biohydrogen

This study examined the effect of various inocula on mixed-culture dark fermentative H₂ production from food waste. Heat-treated and frozen H₂-producing granular sludge (HPG) grown with monomeric sugars showed a higher H₂ yield, production rate, and acidogenic efficiency along with a shorter lag phase than heat-treated methanogenic sludge. Among three different methods of methanogenic sludge inoculation, inoculation after centrifugation showed better H₂ production performance. Propionic acid production and homoacetogenesis were regarded as major H₂-consuming pathways when methanogenic sludge was used, whereas only homoacetogenesis was found in HPG-inoculated fermentation. During fermentation, the abundance of Clostridium increased greater than 48-fold for methanogenic sludge and greater than 108-fold for HPG, respectively. The initial abundance of Clostridium showed a linear relationship with the H₂ production rate and lag-phase time. The use of inoculum with a high abundance of Clostridium is essential for H₂ production from food waste.

Development and Optimization of Djulis Sourdough Bread Fermented by Lactic Acid Bacteria for Antioxidant Capacity

This study developed a nutritionally valuable product with bioactive activity that improves the quality of bread. Djulis (Chenopodium formosanum), a native plant of Taiwan, was fermented using 23 different lactic acid bacteria strains. Lactobacillus casei BCRC10697 was identified as the ideal strain for fermentation, as it lowered the pH value of samples to 4.6 and demonstrated proteolysis ability 1.88 times higher than controls after 24 h of fermentation. Response surface methodology was adopted to optimize the djulis fermentation conditions for trolox equivalent antioxidant capacity (TEAC). The optimal conditions were a temperature of 33.5 °C, fructose content of 7.7%, and dough yield of 332.8, which yielded a TEAC at 6.82 mmol/kg. A 63% increase in TEAC and 20% increase in DPPH were observed when compared with unfermented djulis. Subsequently, the fermented djulis was used in different proportions as a substitute for wheat flour to make bread. The total phenolic and flavonoid compounds were 4.23 mg GAE/g and 3.46 mg QE/g, marking respective increases of 18% and 40% when the djulis was added. Texture analysis revealed that adding djulis increased the hardness and chewiness of sourdough breads. It also extended their shelf life by approximately 2 days. Thus, adding djulis to sourdough can enhance the functionality of breads and may provide a potential basis for developing djulis-based functional food.

Metagenomic Analysis of Bacterial Diversity in Traditional Fermented Foods Reveals Food-Specific Dominance of Specific Bacterial Taxa

Traditional fermented foods have been recognized by various communities to be good for health since ancient times. There is a provincial legacy of traditional fermented foods among the ethnic population of North-East India. Fermented bamboo shoots (local name: Tuaither), soybeans (Bekang), and pork fat (Sa-um) are famous in the Mizoram state and represent a primary portion of the daily diet. These foods are prepared using methods based on cultural traditions inherited from previous generations, and prepared using a relatively uncontrolled fermentation process. Analysis of the bacterial diversity in these foods can provide important information regarding the flavor and texture of the final products of fermentation. Unfortunately, studies on the microbial composition and health benefits of such traditional fermented foods have rarely been documented. Therefore, the present study aims to highlight this bacterial diversity, along with the proximate composition of different traditional fermented foods (Tuaither, Bekang and Sa-um) primarily consumed in Mizoram state, India. Samples were collected on three different days of fermentation (3rd, 5th and 7th day), and bacterial diversity analysis was performed using the V3-V4 variable region of 16S rRNA gene with Illumina sequencing. Results revealed differences in the bacterial composition of dominant group members among all of the three food types. Firmicutes (82.72–94.00%), followed by Proteobacteria (4.67–15.01%), were found to dominate to varying degrees in all three of the fermented foods. However, at genus level high variation was observed in bacterial composition among these three different types of fermented foods. Lactobacillus (91.64–77.16%), Staphylococcus (52.00–17.90%), and Clostridium (72.48–55.40%) exhibited the highest relative abundances in the Tuaither, Bekang and Sa-um foods, respectively, in descending order from the 3rd to 7th day of fermentation. A few of the bacterial genera such as Lactobacilli were positively correlated with fermented bamboo shoot samples, and Staphylococcus was positively correlated with protein, carbohydrate and crude fiber content in soybean samples. In general, Tuaither, Bekang and Sa-um exhibited distinct differences in bacterial composition. This variation may be due to differences in the raw materials and/or methods used in the preparation of the different fermented food products. This is the first study to describe the bacterial composition of these traditional fermented foods using high-throughput sequencing techniques, and could help to drive research attention to comprehensive studies on improving understanding of the role of microbial communities in the preparation of traditional foods and their health benefits.

Production of L (+) Lactic Acid by Lactobacillus casei Ke11: Fed Batch Fermentation Strategies

Lactic acid and its derivatives are widely used in pharmaceutical, leather, textile and food industries. However, until now there have been few systematic reports on fed-batch fermentation for efficient production and high concentration of l-lactic acid by lactic acid bacteria. This study describes the obtainment of L (+) lactic acid from sucrose using the Lactobacillus casei Ke11 strain through different feeding strategies using an accessible pH neutralizer such as CaCO3. The exponential feeding strategy can increase lactic acid production and productivity (175.84 g/L and 3.74 g/L/h, respectively) with a 95% yield, avoiding inhibition by high initial substrate concentration and, combined with the selected agent controller, avoids the cellular stress that could be caused by the high osmotic pressure of the culture media. The purification of the acid using charcoal and celite, followed by the use of a cation exchange column proved to be highly efficient, allowing a high yield of lactic acid, high removal of sugars and proteins. The described process shows great potential for the production of lactic acid, as well as the simple, efficient and low-cost purification method. This way, this work is useful to the large-scale fermentation of L. casei Ke11 for production of l-lactic acid.

Isolation and Identification of Lactic Acid Bacteria from Cow Milk and Milk Products

Lactic acid bacteria (LAB) have long been consumed by people in several fermented foods such as dairy products. A study was conducted on lactating dairy cows to isolate and characterize LAB from dairy products found in and around Bahir-Dar city, North Western Ethiopia. Milk and milk products were randomly collected from dairy farms, milk vending shops, individual households, and supermarkets for bacteriological investigations. A total of sixteen samples were taken from different sources and cultured on different selective media: de Man, Rogosa, and Sharpe (MRS) agar for Lactobacillus spp.; M17 agar for Lactococcus spp.; Rogasa SL agar for Streptococci spp.; and MRS supplemented with cysteine (0.5%) for Bifidobacteria spp. Different laboratory techniques were implemented for LAB isolation and identification. A total of 41 bacterial isolates were grouped under five different genera of LAB and Bifidobacteria spp. were identified based on the growth morphology on the selective media, growth at a different temperature, gas production from glucose, carbohydrate fermentation, and other biochemical tests. LAB genera such as Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, Streptococcus, and Bifidobacterium spp. were isolated and identified from raw milk, cheese, and yogurt. Based on the current study, the majority of the LAB (24.38%) was isolated from cheese and yogurt. Among these, Lactobacillus, Lactococcus (21.94%), Streptococcus (19.51%), Leuconostoc (14.64%), Bifidobacteria (12.19%), and Pediococcus (7.31%) spp. were also identified from these products. Furthermore, based on the bacterial load count and different identification methodologies, our study revealed that Lactobacillus spp. were the dominant LAB isolated from milk and milk products. As a result, since there are few studies on the isolation and identification of lactic acid bacteria from dairy products in Ethiopia, more research studies are needed to complete the identification and characterization to species level and their possible role as probiotics.

Effects of Lactobacillus plantarum on growth traits, slaughter performance, serum markers and intestinal bacterial community of Daheng broilers

Probiotics are expected to be an ideal alternative for antibiotics in the poultry industry. This study aimed to investigate the effect of Lactobacillus plantarum on growth traits, slaughter performance, serum markers and intestinal bacterial community of Daheng broilers. A total of 2400 healthy one-day-old Daheng broilers were randomly divided into 5 groups with 6 replicates per group and 40 individuals per replicate. Birds in control group were fed a basal diet, and others were fed basal diets supplemented with 10⁵ , 10⁶ , 10⁷ and 10⁸  CFU/kg Lactobacillus plantarum, respectively. It turned out that adding Lactobacillus plantarum to diet could significantly improve the serum immune performance of broilers (p < 0.05), enhance the antioxidant capacity to a certain extent (p > 0.05), but had no significant effect on growth traits and slaughter performance. Moreover, Lactobacillus plantarum could improve the diversity of intestinal bacterial community, but with the increase of addition concentration, the diversity would gradually decrease. In conclusion, Lactobacillus plantarum can be used as feed additive in broiler production, but whether it is more effective than antibiotics needs further investigation.

Lactiplantibacillus plantarum 22A-3 isolated from pickle suppresses ovalbumin-induced food allergy in BALB/c mice and 2,4-dinitrochlorobenzene-induced atopic dermatitis in NC/Nga mice

In the previous study, pickle-derived Lactiplantibacillus plantarum 22A-3 (LP22A3) suppressed ear edema in passive cutaneous anaphylaxis by its oral administration. Moreover, LP22A3 treatment directly to RBL-2H3 cells shows no effect on β-hexosaminidase release from RBL-2H3 but inhibited its release using the Caco-2/RBL-2H3 cells co-culture system stimulated with LP22A3 from the apical side. In this study, oral administration of LP22A3 decreased total IgE and ovalbumin (OVA) specific IgE contents in blood of BALB/c mice induced food allergy by OVA. Moreover, its oral administration suppressed the development of dermatitis induced by 2,4-dinitrochlorobenzene (DNCB) which was used to develop atopic dermatitis-like lesions in NC/Nga mice. This alleviation was further correlated with a reduction of elevated serum total IgE, transepidermal water loss and elevated acanthosis in the LP22A3-treated group compared with vehicle-treated positive group. In co-culture system composed of Caco-2 and RBL-2H3 cells, LP22A3 treatment on apical side before or after the sensitization with anti-dinitrophenyl (DNP) IgE antibody indicated the different effect on β-hexosaminidase release from RBL-2H3. Its treatment before the sensitization decreased β-hexosaminidase release, but not after sensitization, indicating that LP22A3 affected mast cells sensitized with allergen through intestinal epithelial cells. These results suggest that LP22A3 may have a potential therapeutic property for Type 1 hypersensitivity and atopic dermatitis.

Comparative genomics analysis of Pediococcus acidilactici species

Pediococcus acidilactici is a reliable bacteriocin producer and a promising probiotic species with wide application in the food and health industry. However, the underlying genetic features of this species have not been analyzed. In this study, we performed a comprehensive comparative genomic analysis of 41 P. acidilactici strains from various ecological niches. The bacteriocin production of 41 strains were predicted and three kinds of bacteriocin encoding genes were identified in 11 P. acidilactici strains, namely pediocin PA-1, enterolysin A, and colicin-B. Moreover, whole-genome analysis showed a high genetic diversity within the population, mainly related to a large proportion of variable genomes, mobile elements, and hypothetical genes obtained through horizontal gene transfer. In addition, comparative genomics also facilitated the genetic explanation of the adaptation for host environment, which specify the protection mechanism against the invasion of foreign DNA (i.e. CRISPR/Cas locus), as well as carbohydrate fermentation. The 41 strains of P. acidilactici can metabolize a variety of carbon sources, which enhances the adaptability of this species and survival in different environments. This study evaluated the antibacterial ability, genome evolution, and ecological flexibility of P. acidilactici from the perspective of genetics and provides strong supporting evidence for its industrial development and application.

Heat-Killed Lactic Acid Bacteria Inhibit Nitric Oxide Production via Inducible Nitric Oxide Synthase and Cyclooxygenase-2 in RAW 264.7 Cells

Heat-killed lactic acid bacteria perform immunomodulatory functions and are advantageous as probiotics, considering their long product shelf-life, easy storage, and convenient transportation. In this study, we aimed to develop appropriate heat treatments for industrial preparation of probiotics with antioxidant activity. Among 75 heat-killed strains, Lactococcus lactis MG5125 revealed the highest nitric oxide inhibition (86.2%), followed by Lactobacillus acidophilus MG4559 (86.0%), Lactobacillus plantarum MG5270 (85.7%), Lactobacillus fermentum MG4510 (85.3%), L. plantarum MG5239 (83.9%), L. plantarum MG5289 (83.2%), and L. plantarum MG5203 (81.8%). Moreover, the heat-killed selected strains markedly inhibited lipopolysaccharide-induced nitric oxide synthase and cyclooxygenase-2 expression. The use of heat-killed bacteria with intact bio-functionality can elongate the shelf-life and simplify the food processing steps of probiotic foods, given their high stability. The antioxidant and immune-modulatory activities of the heat-killed strains selected in this study indicate a strong potential for their utilization probiotic products manufacturing.

Limosilactobacillus fermentum CECT5716: Mechanisms and Therapeutic Insights

Probiotics microorganisms exert their health-associated activities through some of the following general actions: competitive exclusion, enhancement of intestinal barrier function, production of bacteriocins, improvement of altered microbiota, and modulation of the immune response. Among them, Limosilactobacillus fermentum CECT5716 has become one of the most promising probiotics and it has been described to possess potential beneficial effects on inflammatory processes and immunological alterations. Different studies, preclinical and clinical trials, have evidenced its anti-inflammatory and immunomodulatory properties and elucidated the precise mechanisms of action involved in its beneficial effects. Therefore, the aim of this review is to provide an updated overview of the effect on host health, mechanisms, and future therapeutic approaches.

Biodiversity of Lactobacillus helveticus isolates from dairy and cereal fermentations reveals habitat-adapted biotypes

For the present study, we collected 22 Lactobacillus helveticus strains from different dairy (n = 10) and cereal (n  = 12) fermentations to investigate their biodiversity and to uncover habitat-specific traits. Biodiversity was assessed by comparison of genetic fingerprints, low-molecular-weight subproteomes, metabolic and enzymatic activities, growth characteristics and acidification kinetics in food matrices. A clear distinction between the dairy and cereal strains was observed in almost all examined features suggesting that the different habitats are domiciled by different L. helveticus biotypes that are adapted to the specific environmental conditions. Analysis of the low-molecular-weight subproteome divided the cereal isolates into two clusters, while the dairy isolates formed a separate homogeneous cluster. Differences regarding carbohydrate utilization were observed for lactose, galactose, sucrose and cellobiose as well as for plant-derived glucosides. Enzymatic differences were observed mainly for ß-galactosidase and ß-glucosidase activities. Further, growth temperature was optimal in the range from 33 to 37°C for the cereal strains, whereas the dairy strains showed optimal growth at 40°C. Taken together, adaptation of the various biotypes results in a growth benefit in the particular environment. Acidification and growth tests using either sterile skim milk or a wheat flour extract confirmed these results. Differentiation of these biotypes and their physiological characteristics enables knowledge-based starter culture development for cereal versus dairy products within one species.

Study of the bacterial profile of raw milk butter, made during a challenge test with Listeria monocytogenes, depending on cream maturation temperature

Bacteria can play different roles and impart various flavors and characteristics to food. Few studies have described bacterial microbiota of butter. In this study, next-generation sequencing was used to determine bacterial content of raw milk butter, processed during a challenge test, depending on cream maturation temperature and on the presence or not of L. monocytogenes. Two batches were produced. pH and microbiological analyses were conducted during cream maturation and butter storage. DNA was also isolated from all samples for 16S rRNA amplicon sequencing analysis. For butter made from cream matured at 14 °C, a growth potential of L. monocytogenes of - 1.72 log cfu/g was obtained. This value corresponds to the difference between the median of counts at the end of storage and the median of counts at the beginning of storage. This butter (pH value of 4.75 ± 0.04) was characterized by a dominance of Lactococcus. The abundance of Lactococcus was significantly higher in inoculated samples than in control samples (p value < 0.05). Butter made from cream matured at 4 °C (pH value of 6.81 ± 0.01) presented a growth potential of 1.81 log cfu/g. It was characterized by the abundance of psychrotrophic bacteria mainly Pseudomonas. This study demonstrated that cream maturation temperature impacts butter microbiota, affecting thus product's characteristics and its ability to support or not the growth of pathogens like L. monocytogenes.

Safety assessment of Lactobacillus reuteri IDCC 3701 based on phenotypic and genomic analysis

Purpose

Lactobacillus reuteri is one of the most largely studied human-commensal bacteria and widely used as a form of probiotics. Safety of probiotics has become increasingly important for human consumption due to increasing health-concerns in food industry. In this study, the safety of L. reuteri IDCC 3701 isolated from human breast milk was thoroughly investigated.

Methods

Whole-genome sequence analysis was performed to identify antibiotic resistance and toxigenicity of L. reuteri IDCC 3701. Phenotypic analysis such as minimal inhibitory concentration, β-hemolysis, extracellular enzyme activity, and the production of biological amines and L/D-lactate, was investigated. Finally, acute oral toxicity test was performed to access L. reuteri IDCC 3701 safety.

Results

Although multiple resistances to gentamicin and kanamycin were observed in L. reuteri IDCC 3701, it was revealed that these resistances are intrinsic and not transferable through whole-genome analysis. In addition, various phenotypic analysis concerning hemolysis, enzyme activity, and D-lactate production did not show any negative results. Although L. reuteri IDCC 3701 harbors a histidine decarboxylase gene, no biogenic amines were detected. Finally, L. reuteri IDCC 3701 exhibited no evidence of acute toxicity according to an in vivo study.

Conclusion

Our findings demonstrate that L. reuteri IDCC 3701 is considered to be safe for human consumption as probiotics based on the in silico, in vitro and in vivo studies.