Bifidobacterium longum LBUX23 Isolated from Feces of a Newborn; Potential Probiotic Properties and Genomic Characterization

Hypoglycemic, Antioxidant Activities, and Probiotic Characteristics of Lacticaseibacillus rhamnosus LBUX2302 Isolated from Stool Samples of Neonates

Lacticaseibacillus species have shown potential in managing hyperglycemia, hypercholesterolemia, and oxidative stress, depending on the strain and species. This study aimed to isolate a novel Lacticaseibacillus rhamnosus strain from healthy newborns and assess its hypoglycemic and antioxidative activity, along with other probiotic properties. A non-hemolytic L. rhamnosus LBUX2302 was isolated, and it exhibited survival rates of 2.7%, 22%, and 27.5% at pH 2, 3, and 5 for 120 min. It metabolized various carbon sources and showed resistance to gentamicin, dicloxacillin, and penicillin; coaggregated with Salmonella typhi ATCC14028, Staphylococcus aureus STCC6538, and Escherichia coli O157:H7. L. rhamnosus LBUX2302 showed hydrophobicity, autoaggregation, and adhesion to HaCat, HeLa, MCF-7, SK-LU-1, and SW620 cell lines. It also exhibited extracellular activity of bile salt hydrolase. Enzymatic inhibition assays revealed 66% and 24% inhibitions of α-amylase and α-glucosidase, respectively. Its cell-free supernatant inhibited DPPH (89%), hydroxyl (81%), and superoxide anion radicals (61%). Also, antioxidant activity was observed in whole cells and cell fragments. Finally, the presence of ferulic acid activity was detected. The results highlight L. rhamnosus LBUX2302 as a promising probiotic with hypoglycemic and antioxidant effects, warranting further in vivo evaluation for its possible inclusion in functional food and health formulations.

Analysis of the antioxidant properties of Lactiplantibacillus plantarum EA3 isolated from fermented yak milk based on whole genome sequencing

Lactiplantibacillus plantarum EA3 was isolated from traditional fermented yak milk in the Gannan Tibetan Autonomous Prefecture of Gansu Province, China. Whole-genome analysis revealed that the EA3 genome is 3.47 Mb in size, consisting of a circular chromosome and three plasmids. The circular chromosome measures 3,318,230 bp in length with a GC content of 44.48 %. Functional annotation identified at least ten regulatory pathways and 33 protein-coding genes associated with oxidative stress, whose abundance correlates with free radical scavenging rates and oxygen tolerance. Additionally, genes encoding ten acid-tolerant proteins, ten bile salt-tolerant proteins, 26 adhesive proteins, and 12 bacteriocin-related proteins were detected. In vitro experiments have confirmed that EA3 can withstand up to 4 mM H2O2. Both the cell suspension and fermentation supernatant of EA3 exhibited significant radical scavenging activity and reducing power, highlighting its robust antioxidant properties. EA3 demonstrated high survival rates under harsh conditions, including pH 2.5 (90.24 %) and 1.2 % bile salt, and displayed antibacterial activity against Salmonella and Staphylococcus aureus. The EA3 genome lacked virulence factors, and its sensitivity to antibiotics, absence of hemolytic activity, and inability to produce biogenic amines confirmed its safety. These findings suggest that Lactiplantibacillus plantarum EA3 possesses exceptional antioxidant properties, making it a promising candidate for functional food production.

The Genomic Characteristics of Potential Probiotics: Two Streptococcus salivarius Isolates from a Healthy Individual in China

The isolation and characterization of novel probiotics from dairy products, fermented foods, and the gut have gained significant attention. In particular, Streptococcus salivarius shows promise for use in oral probiotic preparations. In this study, we isolated two strains of S. salivarius-S.82.15 and S.82.20-from the oral cavity of a healthy individual. These strains exhibited distinct antimicrobial profiles. We thoroughly assessed the morphology and growth patterns of both strains and confirmed auto-aggregation and hemolytic activity. Through comprehensive genomic analysis, we found notable strain differences within the same bacterial species isolated from the same individual. Notably, the presence or absence of plasmids varied between the two strains. The genome of S.82.15 spans 2,175,688 bps and contains 1994 coding DNA sequences (CDSs), while S.82.20 has a genome size of 2,414,610 bps, a GC content of 40.62%, and 2276 annotated CDSs. Both strains demonstrated antibacterial activity against Group A Streptococcus (GAS), Micrococcus. luteus, and Porphyromonas gingivalis. To investigate the antibacterial properties further, we identified a gene cluster of salivaricin 9 on the plasmid of S.82.20 and a blp gene family on the chromosomes of both S.82.15 and S.82.20. Moreover, the gene expression of the blp family was upregulated when the isolated strains were co-cultured with GAS.

Regulatory mechanisms of the probiotic-targeted gut-liver axis for the alleviation of alcohol-related liver disease: a review

Alcohol abuse-triggered alcohol-related liver disease (ALD) has become as a global public health concern that substantially affects the well-being and clinical status of patients. Although modern medicine provides various treatments for ALD, their effectiveness is limited and can lead to adverse side effects. Probiotics have been employed to prevent, alleviate, and even treat ALD, with promising results. However, few comprehensive reviews are available on how they mitigate ALD by targeting the gut-liver axis. This review systematically clarifies the specific mediators of the gut-liver axis in healthy states. It also describes the alterations observed in ALD. Furthermore, this review thoroughly summarizes the underlying mechanisms through which probiotics act on the gut-liver axis to relieve ALD. It also discusses the current status and challenges faced in clinical research applications. Finally, we discuss the challenges and future prospects of using probiotics to treat ALD. This review improves our understanding of ALD and supports the development and application of probiotics that target the gut-liver axis for therapeutic use.

The gut core microbial species Bifidobacterium longum: Colonization, mechanisms, and health benefits

Bifidobacterium longum (B. longum) is a species of the core microbiome in the human gut, whose abundance is closely associated with host age and health status. B. longum has been shown to modulate host gut microecology and have the potential to alleviate various diseases. Comprehensive understanding on the colonization mechanism of B. longum and mechanism of the host-B. longum interactions, can provide us possibility to prevent and treat human diseases through B. longum-directed strategies. In this review, we summarized the gut colonization characteristics of B. longum, discussed the diet factors that have ability/potential to enrich indigenous and/or ingested B. longum strains, and reviewed the intervention mechanisms of B. longum in multiple diseases. The key findings are as follows: First, B. longum has specialized colonization mechanisms, like a wide carbohydrate utilization spectrum that allows it to adapt to the host's diet, species-level conserved genes encoding bile salt hydrolase (BSHs), and appropriate bacterial surface structures. Second, dietary intervention (e.g., anthocyanins) could effectively improve the gut colonization of B. longum, demonstrating the feasibility of diet-tuned strain colonization. Finally, we analyzed the skewed abundance of B. longum in different types of diseases and summarized the main mechanisms by which B. longum alleviates digestive (repairing the intestinal mucosal barrier by stimulating Paneth cell activity), immune (up-regulating the regulatory T cell (Treg) populations and maintaining the balance of Th1/Th2), and neurological diseases (regulating the kynurenine pathway and quinolinic acid levels in the brain through the gut-brain axis).

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.

Cholesterol lowering in diet-induced hypercholesterolemic mice using Lactobacillus bile salt hydrolases with different substrate specificities

The cholesterol-lowering effect of lactic acid bacteria with high activity of bile salt hydrolase (BSH) is unclear. We believe that distinguishing BSH substrate specificity is necessary to study the effect of various BSH enzymes. We engineered a BSH mutant enzyme recombinant strain named F67A, which exclusively hydrolyzes taurocholic acid (TCA) using site-directed mutagenesis, and a previously lab-constructed BSH recombinant strain, YB81 that exclusively hydrolyzes glycocholic acid (GCA). We also constructed the recombinant strain named NB5462, which carries the empty pSIP411 plasmid and was used as a blank control strain. The intestinal flora in pseudo-germ-free (PGF) mice in which intestinal flora were eliminated via antibiotics, and F67A successfully reduced serum cholesterol levels in high-cholesterol diet-fed mice, whereas YB81 did not yield the same results. However, YB81 regained its cholesterol-lowering capacity in specific pathogen-free (SPF) mice with intact intestinal flora. The cholesterol-lowering mechanism of F67A involved modifying the bile acid pool through BSH enzyme activity. This adjustment regulated the expression of intestinal farnesoid X receptor and subsequently elevated hepatic cholesterol 7α-hydroxylase (CYP7A1), effectively reducing cholesterol levels. Conversely, GCA, the substrate of YB81, was found in minimal quantities in mice, preventing it from inducing changes in bile acid pools. In the presence of intestinal flora, the YB81 BSH enzyme induced notable alterations in bile acids by regulating changes in the intestinal flora and BSH within the flora, ultimately resulting in cholesterol reduction. This is the first study investigating the substrate specificity of BSH, demonstrating that different substrate-specific BSH enzymes exhibit cholesterol-lowering properties. Additionally, we elaborate on the mechanism of BSH-mediated enterohepatic axis regulation.

metaProbiotics: a tool for mining probiotic from metagenomic binning data based on a language model

Beneficial bacteria remain largely unexplored. Lacking systematic methods, understanding probiotic community traits becomes challenging, leading to various conclusions about their probiotic effects among different publications. We developed language model-based metaProbiotics to rapidly detect probiotic bins from metagenomes, demonstrating superior performance in simulated benchmark datasets. Testing on gut metagenomes from probiotic-treated individuals, it revealed the probioticity of intervention strains-derived bins and other probiotic-associated bins beyond the training data, such as a plasmid-like bin. Analyses of these bins revealed various probiotic mechanisms and bai operon as probiotic Ruminococcaceae's potential marker. In different health-disease cohorts, these bins were more common in healthy individuals, signifying their probiotic role, but relevant health predictions based on the abundance profiles of these bins faced cross-disease challenges. To better understand the heterogeneous nature of probiotics, we used metaProbiotics to construct a comprehensive probiotic genome set from global gut metagenomic data. Module analysis of this set shows that diseased individuals often lack certain probiotic gene modules, with significant variation of the missing modules across different diseases. Additionally, different gene modules on the same probiotic have heterogeneous effects on various diseases. We thus believe that gene function integrity of the probiotic community is more crucial in maintaining gut homeostasis than merely increasing specific gene abundance, and adding probiotics indiscriminately might not boost health. We expect that the innovative language model-based metaProbiotics tool will promote novel probiotic discovery using large-scale metagenomic data and facilitate systematic research on bacterial probiotic effects. The metaProbiotics program can be freely downloaded at https://github.com/zhenchengfang/metaProbiotics.