An emerging strategy: probiotics enhance the effectiveness of tumor immunotherapy via mediating the gut microbiome.

The occurrence and progression of tumors are often accompanied by disruptions in the gut microbiota. Inversely, the impact of the gut microbiota on the initiation and progression of cancer is becoming increasingly evident, influencing the tumor microenvironment (TME) for both local and distant tumors. Moreover, it is even suggested to play a significant role in the process of tumor immunotherapy, contributing to high specificity in therapeutic outcomes and long-term effectiveness across various cancer types. Probiotics, with their generally positive influence on the gut microbiota, may serve as effective agents in synergizing cancer immunotherapy. They play a crucial role in activating the immune system to inhibit tumor growth. In summary, this comprehensive review aims to provide valuable insights into the dynamic interactions between probiotics, gut microbiota, and cancer. Furthermore, we highlight recent advances and mechanisms in using probiotics to improve the effectiveness of cancer immunotherapy. By understanding these complex relationships, we may unlock innovative approaches for cancer diagnosis and treatment while optimizing the effects of immunotherapy.

Lactic acid bacteria fermentation improves physicochemical properties, bioactivity, and metabolic profiles of Opuntia ficus-indica fruit juice.

Lactic acid bacteria (LAB) fermentation has been proven to promote human health. The effect of different LAB fermentation on the quality of Opuntia ficus-indica fruit juice (OFIJ) was investigated. OFIJ was an excellent substrate for fermentation, with colony counts of more than 8 log CFU/mL after fermentation. The fermentation altered the acid and sugar contents. Simultaneously, the total phenolic and anthocyanin contents significantly increased. Antioxidant activity enhanced significantly in Lactiplantibacillus plantarum HNU082-fermented OFIJ, primarily in ABTS+ (increased by 16.81%) and DPPH (increased by 23.62%) free radical scavenging ability. Lacticaseibacillus paracasei HNU502-fermented OFIJ showed the most potent inhibition of xanthine oxidase (IC50 = 31.01 ± 3.88 mg TAC/L). Analysis of volatile and non-volatile compounds indicated that fermentation changed the flavor quality and metabolic profiles and caused the most significant modifications in amino acid metabolism. These findings offer valuable information into processing of OFIJ, making it a great choice for functional foods.

Tropical postbiotics alleviate the disorders in the gut microbiota and kidney damage induced by ochratoxin A exposure.

Ochratoxin A (OTA), commonly found in various foods, significantly impacts the health of humans and animals, especially their kidneys. Our study explores OTA's effects on the gut microbiota and kidney damage while examining how postbiotics offer protection. Using metagenomic sequencing, we observed that OTA increased the potential gut pathogens such as Alistipes, elevating detrimental metabolites and inflammation. Also, OTA inhibited the Nrf2/HO-1 pathway, reducing kidney ROS elimination and leading to cellular ferroptosis and subsequent kidney damage. Postbiotics mitigate OTA's effects by downregulating the abundance of the assimilatory sulfate reduction IV pathway and virulence factors associated with iron uptake and relieving the inhibition of OTA on Nrf2/HO-1, restoring ROS-clearing capabilities and thereby alleviating chronic OTA-induced kidney damage. Understanding the OTA-gut-kidney link provides new approaches for preventing kidney damage, with postbiotics showing promise as a preventive treatment.

A key genetic factor governing arabinan utilization in the gut microbiome alleviates constipation.

Impaired gastrointestinal motility is associated with gut dysbiosis. Probiotics, such as Bifidobacteria, can improve this bowel disorder; however, efficacy is strain-dependent. We determine that a genetic factor, the abfA cluster governing arabinan utilization, in Bifidobacterium longum impacts treatment efficacy against functional constipation (FC). In mice with FC, B. longum, but not an abfA mutant, improved gastrointestinal transit time, an affect that was dependent upon dietary arabinan. abfA genes were identified in other commensal bacteria, whose effects in ameliorating murine FC were similarly abfA-dependent. In a double-blind, randomized, placebo-controlled clinical trial, supplementation with abfA-cluster-carrying B. longum, but not an abfA-deficient strain, enriched arabinan-utilization residents, increased beneficial metabolites, and improved FC symptoms. Across human cohorts, abfA-cluster abundance can predict FC, and transplantation of abfA cluster-enriched human microbiota to FC-induced germ-free mice improved gut motility. Collectively, these findings demonstrate a role for microbial abfA cluster in ameliorating FC, establishing principles for genomics-directed probiotic therapies.

Native microbiome dominates over host factors in shaping the probiotic genetic evolution in the gut.

Probiotics often acquire potentially adaptive mutations in vivo, gaining new functional traits through gut selection. While both the host and microbiome can contribute to probiotics' genetic evolution, separating the microbiome and the host's contribution to such selective pressures remains challenging. Here, we introduced germ-free (GF) and specific pathogen-free (SPF) mouse models to track how probiotic strains, i.e., Lactiplantibacillus plantarum HNU082 (Lp082) and Bifidobacterium animalis subsp. lactis V9 (BV9), genetically evolved under selection pressures derived from host factors alone and both host and microbial ecological factors. Notably, compared to the genome of a probiotic strain before consumption, the host only elicited <15 probiotic mutations in probiotic genomes that emerged in the luminal environment of GF mice, while a total of 840 mutations in Lp082 mutants and 21,579 mutations in BV9 were found in SPF mice, <0.25% of those derived from both factors that were never captured by other experimental evolution studies, indicating that keen microbial competitions exhibited the predominant evolutionary force in shaping probiotic genetic composition (>99.75%). For a given probiotic, functional genes occurring in potentially adaptive mutations induced by hosts (GF mice) were all shared with those found in mutants of SPF mice. Collectively, the native microbiome consistently drove a more rapid and divergent genetic evolution of probiotic strains in seven days of colonization than host factors did. Our study further laid a theoretical foundation for genetically engineering probiotics for better gut adaptation through in vitro artificial gut ecosystems without the selection pressures derived from host factors.

Cross-cohort single-nucleotide-variant profiling of gut microbiota suggests a novel gut-health assessment approach.

IMPORTANCE: Most studies focused much on the change in abundance and often failed to explain the microbiome variation related to disease conditions, Herein, we argue that microbial genetic changes can precede the ecological changes associated with the host physiological changes and, thus, would offer a new information layer from metagenomic data for predictive modeling of diseases. Interestingly, we preliminarily found a few genetic biomarkers on SCFA production can cover most chronic diseases involved in the meta-analysis. In the future, it is of both scientific and clinical significance to further explore the dynamic interactions between adaptive evolution and ecology of gut microbiota associated with host health status.

Lactobacillus gasseri CKCC1913 mediated modulation of the gut-liver axis alleviated insulin resistance and liver damage induced by type 2 diabetes.

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by dysregulation of lipid metabolism, insulin resistance, and gut microbiota disorder. Compared to drug interventions, probiotic interventions may have a more enduring effect without producing any side effects. Thus, the potential of probiotics as a therapeutic approach for diabetes and other metabolic disorders has gained increasing attention in recent years. In this study, we evaluated the therapeutic efficacy of Lactobacillus gasseri CKCC1913, a potential probiotic strain, in high-fat diet-induced insulin-resistant diabetes using the C57BL/6J mouse animal model. From the results, L. gasseri CKCC1913 has been shown to increase glucose tolerance, reduce fasting blood glucose levels in diabetic mice, and reduce the expression of pro-inflammatory cytokines, such as TNF-α and IL-6. Besides, L. gasseri CKCC1913 intervention effectively alleviated oxidative stress damage by increasing SOD activity, decreasing MDA levels, reducing insulin resistance, and improving dyslipidemia caused by diabetes. The potential mechanism of L. gasseri CKCC1913 in improving metabolic health and alleviating diabetes involves an increased abundance of beneficial bacteria, such as Parabacteroides merdae, which directly produce short-chain fatty acids that help regulate immune cells and reduce inflammation. SCFAs also enter the bloodstream and promote antioxidant enzyme activity in the liver, protecting against oxidative damage. Additionally, L. gasseri CKCC1913 influences local bacterial metabolism pathways, such as the superpathway of unsaturated fatty acid biosynthesis, leading to an increase in unsaturated fatty acids, increasing high-density lipoprotein cholesterol (HDL-C) levels and improving lipid metabolism and glucose control in diabetic mice. In summary, in this study, L. gasseri CKCC1913 and its potential impact on metabolic health highlight the promising potential of probiotics as a therapeutic approach for diabetes. Future research should focus on identifying the optimal dose and duration, investigating the long-term effects and mechanisms of action, and exploring the potential use of probiotics as an adjunct to other therapies or in preventing metabolic disorders.

Short-term arecoline exposure affected the systemic health state of mice, in which gut microbes played an important role.

Arecoline is a critical bioactive component in areca nuts with toxicity and pharmacological activities. However, its effects on body health remain unclear. Here, we investigated the effects of arecoline on physiologic and biochemical parameters in mouse serum, liver, brain, and intestine. The effect of arecoline on gut microbiota was investigated based on shotgun metagenomic sequencing. The results showed that arecoline promoted lipid metabolism in mice, manifested as significantly reduced serum TC and TG and liver TC levels and a reduction in abdominal fat accumulation. Arecoline intake significantly modulated the neurotransmitters 5-HT and NE levels in the brain. Notably, arecoline intervention significantly increased serum IL-6 and LPS levels, leading to inflammation in the body. High-dose arecoline significantly reduced liver GSH levels and increased MDA levels, which led to oxidative stress in the liver. Arecoline intake promoted the release of intestinal IL-6 and IL-1ß, causing intestinal injury. In addition, we observed a significant response of gut microbiota to arecoline intake, reflecting significant changes in diversity and function of the gut microbes. Further mechanistic exploration suggested that arecoline intake can regulate gut microbes and ultimately affect the host's health. This study provided technical help for the pharmacochemical application and toxicity control of arecoline.

Lactobacillus fermentum HNU312 alleviated oxidative damage and behavioural abnormalities during brain development in early life induced by chronic lead exposure.

Lead exposure is a global public health safety issue that severely disrupts brain development and causes damage to the nervous system in early life. Probiotics and gut microbes have been highlighted for their critical roles in mitigating lead toxicity. However, the underlying mechanisms by which they work yet to be fully explored. Here, we designed a two-stage experiment using the probiotic Lactobacillus fermentum HNU312 (Lf312) to uncover how probiotics alleviate lead toxicity to the brain during early life. First, we explored the tolerance and adsorption of Lf312 to lead in vitro. Second, the adsorption capacity of the strain was determined and confirmed in vivo. The shotgun metagenome sequencing showed lead exposure-induced imbalance and dysfunction of the gut microbiome. In contrast, Lf312 intake significantly modulated the structure of the microbiome, increased the abundance of beneficial bacteria and short-chain fatty acids (SCFAs)-producing bacteria, and upregulated function-related metabolic pathways such as antioxidants. Notably, Lf312 enhanced the integrity of the blood-brain barrier by increasing the levels of SCFAs in the gut, alleviated inflammation in the brain, and ultimately improved anxiety-like and depression-like behaviours induced by lead exposure in mice. Subsequently, the effective mechanism was confirmed, highlighting that Lf312 worked through integrated strategies, including ionic adsorption and microbiota-gut-brain axis regulation. Collectively, this work elucidated the mechanism by which the gut microbiota mitigates the toxic effects of lead in the brain and provides preventive measures and intervention measures for brain damage due to mass lead poisoning in children.

Two sides of the same coin: Meta-analysis uncovered the potential benefits and risks of traditional fermented foods at a large geographical scale.

Traditional fermented foods, which are well-known microbial resources, are also bright national cultural inheritances. Recently, traditional fermented foods have received great attention due to their potential probiotic properties. Based on shotgun metagenomic sequencing data, we analyzed the microbial diversity, taxonomic composition, metabolic pathways, and the potential benefits and risks of fermented foods through a meta-analysis including 179 selected samples, as well as our own sequencing data collected from Hainan Province, China. As expected, raw materials, regions (differentiated by climatic zones), and substrates were the main driving forces for the microbial diversity and taxonomic composition of traditional fermented foods. Interestingly, a higher content of beneficial bacteria but a low biomass of opportunistic pathogens and antibiotic resistance genes were observed in the fermented dairy products, indicating that fermented dairy products are the most beneficial and reliable fermented foods. In contrast, despite the high microbial diversity found in the fermented soy products, their consumption risk was still high due to the enrichment of opportunistic pathogens and transferable antibiotic resistance genes. Overall, we provided the most comprehensive assessment of the microbiome of fermented food to date and generated a new view of its potential benefits and risks related to human health.

Expanding the Colorectal Cancer Biomarkers Based on the Human Gut Phageome.

With the increasing prevalence of colorectal cancer (CRC), extending the present biomarkers for the diagnosis of colorectal cancer is crucial. Previous studies have highlighted the importance of bacteriophages in gastrointestinal diseases, suggesting the potential value of gut phageome in early CRC diagnostic. Here, based on 317 metagenomic samples of three discovery cohorts collected from China (Hong Kong), Austria, and Japan, five intestinal bacteriophages, including Fusobacterium nucleatum, Peptacetobacter hiranonis, and Parvimonas micra phages were identified as potential CRC biomarkers. The five CRC enriched bacteriophagic markers classified patients from controls with an area under the receiver-operating characteristics curve (AUC) of 0.8616 across different populations. Subsequently, we used a total of 80 samples from China (Hainan) and Italy for validation. The AUC of the validation cohort is 0.8197. Moreover, to further explore the specificity of the five intestinal bacteriophage biomarkers in a broader background, we performed a confirmatory meta-analysis using two inflammatory bowel disease cohorts, ulcerative colitis (UC) and Crohn's disease (CD). Excitingly, we observed that the five CRC-enriched phage markers also exhibited high discrimination in UC (AUC = 78.02%). Unfortunately, the five CRC-rich phage markers did not show high resolution in CD (AUC = 48.00%). The present research expands the potential of microbial biomarkers in CRC diagnosis by building a more accurate classification model based on the human gut phageome, providing a new perspective for CRC gut phagotherapy. IMPORTANCE Worldwide, by 2020, colorectal cancer has become the third most common cancer after lung and breast cancer. Phages are strictly host-specific, and this specificity makes them more accurate as biomarkers, but phage biomarkers for colorectal cancer have not been thoroughly explored. Therefore, it is crucial to extend the existing phage biomarkers for the diagnosis of colorectal cancer. Here, we innovatively constructed a relatively accurate prediction model, including: three discovery cohorts, two additional validation cohorts and two cross-disease cohorts. A total of five possible biomarkers of intestinal bacteriophages were obtained. They are Peptacetobacter hiranonis Phage, Fusobacterium nucleatum animalis 7_1 Phage, Fusobacterium nucleatum polymorphum Phage, Fusobacterium nucleatum animalis 4_8 Phage, and Parvimonas micra Phage. This study aims at identifying fine-scale species-strain level phage biomarkers for colorectal cancer diseases, so as to expand the existing CRC biomarkers and provide a new perspective for intestinal phagocytosis therapy of colorectal cancer.

Metagenomics assembled genome scale analysis revealed the microbial diversity and genetic polymorphism of Lactiplantibacillus plantarum in traditional fermented foods of Hainan, China.

Exploring the microbiome in fermented foods and their effects on food quality and sustainability is beneficial to provide data support for understanding how they affects human physiology. Here, metagenomic sequencing and metagenomic assembled genomes (MAGs) were applied to appraise the microbial diversity of fermented Yucha (FYC) and fermented vegetables (FVE). The antibiotic resistance genes (ARGs) enrichment and genetic polymorphism of Lactiplantibacillus plantarum in fermented foods of different regions were compared. The results showed that Lactiplantibacillus plantarum was the dominant species in FYC, while Lactiplantibacillus fermentum in FVE occupied the dominant position. From 32 high-quality MAGs, the central differential Lactic acid bacteria were higher in FVE. By comparing the Lactiplantibacillus plantarum MAGs in Hainan and Other regions, we found that the total Single Nucleotide Polymorphisms of Lactiplantibacillus plantarum in Hainan were significantly higher than other areas. Six non-synonymous mutations were included in the primary differential mutation, especially TrkA family potassium uptake protein and MerR family transcriptional regulator, which may be related to the hypersaline environment and highest ARGs enrichment in Hainan. This research provides valuable insight into our understanding of the microbiome of fermented food. Meanwhile, the analysis of Lactiplantibacillus plantarum genetic polymorphism based on MAGs helps us understand this strain's evolutionary history.

Lactiplantibacillus plantarum HNU082 inhibited the growth of Fusobacterium nucleatum and alleviated the inflammatory response introduced by F. nucleatum invasion.

As a potential biomarker, there is increasing evidence showing that Fusobacterium nucleatum is positively correlated with the occurrence and development of colorectal cancer. Although antibiotics were expected to eliminate F. nucleatum, the side effects associated with gut microbiotal disorders have to be considered. Here, by performing shotgun metagenomic and transcriptome sequencing, we systematically evaluated the antagonistic effects of probiotic Lactiplantibacillus plantarum HNU082 (Lp082) on F. nucleatum in vivo and in vitro. The results showed that the F. nucleatum invasion significantly altered the host intestinal microbiome including the microbial composition, specific species, metabolic pathways and metabolites, as well as impacted the transcriptome of the intestinal epithelial cells. Moreover, the F. nucleatum invasion triggered inflammatory cytokines and inflammatory responses in the intestine but did not develop into colorectal cancer. Excitingly, the Lp082 intervention inhibited the growth of F. nucleatum both in vivo and in vitro and alleviated the inflammatory response introduced by F. nucleatum invasion. Further network-based mechanism exploration demonstrated that Lp082, which negatively correlated to F. nucleatum, maintained the intestinal microbiome homeostasis and prompted the production of beneficial metabolites in the intestine which decreased the expression of inflammatory cytokines in a mouse model. The present research suggested a feasible probiotic intervention strategy for F. nucleatum antagonism in vivo, which may prevent colorectal cancer at the early stage.

Probiotic consumption influences universal adaptive mutations in indigenous human and mouse gut microbiota.

The adaptive evolution in indigenous intestinal microbes derived from probiotics is critical to safety and efficacy evaluation of probiotics, yet it is still largely underexplored. Here, through 11 publicly accessible datasets, we demonstrated that probiotic consumption can lead to widespread single-nucleotide variants (SNVs) in the native microbiota. Interestingly, the same probiotic strains introduced far more SNVs in mouse gut than humans. Furthermore, the pattern of probiotics-induced SNVs was highly probiotic-strain specific, and 17 common SNVs in Faecalibacterium prausnitzii genome were identified cross studies, which might lead to changes in bacterial protein structure. Further, nearly 50% of F. prausnitzii SNVs can be inherited for six months in an independent human cohort, whereas the other half only transiently occurred. Collectively, our study substantially extended our understanding of co-evolution of the probiotics and the indigenous gut microbiota, highlighting the importance of assessment of probiotics efficacy and safety in an integrated manner.

Probiotic Bifidobacterium longum supplied with methimazole improved the thyroid function of Graves' disease patients through the gut-thyroid axis.

Graves' disease (GD) is an autoimmune disorder that frequently results in hyperthyroidism and other symptoms. Here, we designed a 6-month study with patients divided into three treatment groups, namely, methimazole (MI, n = 8), MI + black bean (n = 9) and MI + probiotic Bifidobacterium longum (n = 9), to evaluate the curative effects of probiotics supplied with MI on thyroid function of patients with GD through clinical index determination and intestinal microbiota metagenomic sequencing. Unsurprisingly, MI intake significantly improved several thyroid indexes but not the most important thyrotropin receptor antibody (TRAb), which is an indicator of the GD recurrence rate. Furthermore, we observed a dramatic response of indigenous microbiota to MI intake, which was reflected in the ecological and evolutionary scale of the intestinal microbiota. In contrast, we did not observe any significant changes in the microbiome in the MI + black bean group. Similarly, the clinical thyroid indexes of patients with GD in the probiotic supplied with MI treatment group continued to improve. Dramatically, the concentration of TRAb recovered to the healthy level. Further mechanistic exploration implied that the consumed probiotic regulated the intestinal microbiota and metabolites. These metabolites impacted neurotransmitter and blood trace elements through the gut-brain axis and gut-thyroid axis, which finally improved the host's thyroid function.

Candidate probiotic Lactiplantibacillus plantarum HNU082 rapidly and convergently evolves within human, mice, and zebrafish gut but differentially influences the resident microbiome.

BACKGROUND: Improving probiotic engraftment in the human gut requires a thorough understanding of the in vivo adaptive strategies of probiotics in diverse contexts. However, for most probiotic strains, these in vivo genetic processes are still poorly characterized. Here, we investigated the effects of gut selection pressures from human, mice, and zebrafish on the genetic stability of a candidate probiotic Lactiplantibacillus plantarum HNU082 (Lp082) as well as its ecological and evolutionary impacts on the indigenous gut microbiota using shotgun metagenomic sequencing in combination with isolate resequencing methods. RESULTS: We combined both metagenomics and isolate whole genome sequencing approaches to systematically study the gut-adaptive evolution of probiotic L. plantarum and the ecological and evolutionary changes of resident gut microbiomes in response to probiotic ingestion in multiple host species. Independent of host model, Lp082 colonized and adapted to the gut by acquiring highly consistent single-nucleotide mutations, which primarily modulated carbohydrate utilization and acid tolerance. We cultivated the probiotic mutants and validated that these gut-adapted mutations were genetically stable for at least 3 months and improved their fitness in vitro. In turn, resident gut microbial strains, especially competing strains with Lp082 (e.g., Bacteroides spp. and Bifidobacterium spp.), actively responded to Lp082 engraftment by accumulating 10-70 times more evolutionary changes than usual. Human gut microbiota exhibited a higher ecological and genetic stability than that of mice. CONCLUSIONS: Collectively, our results suggest a highly convergent adaptation strategy of Lp082 across three different host environments. In contrast, the evolutionary changes within the resident gut microbes in response to Lp082 were more divergent and host-specific; however, these changes were not associated with any adverse outcomes. This work lays a theoretical foundation for leveraging animal models for ex vivo engineering of probiotics to improve engraftment outcomes in humans. Video abstract.

Synergistic Effects of the Jackfruit Seed Sourced Resistant Starch and Bifidobacterium pseudolongum subsp. globosum on Suppression of Hyperlipidemia in Mice.

Approximately 17 million people suffer from cardiovascular diseases caused by hyperlipidemia, making it a serious global health concern. Among others, resistant starch (RS) has been widely used as a prebiotic in managing hyperlipidemia conditions. However, some studies have reported limited effects of RS on body weight and blood lipid profile of the host, suggesting further investigation on the synergistic effects of RS in combination with probiotics as gut microbes plays a role in lipid metabolism. This study evaluated the effects of jackfruit seed sourced resistant starch (JSRS) as a novel RS on mice gut microbes and hyperlipidemia by performing 16s rRNA and shotgun metagenomic sequencing. The results showed that 10% JSRS had a limited preventive effect on bodyweight and serum lipid levels. However, the JSRS promoted the growth of Bifidobacterium pseudolongum, which indicated the ability of B. pseudolongum for JSRS utilization. In the validation experiment, B. pseudolongum interacted with JSRS to significantly reduce bodyweight and serum lipid levels and had a therapeutic effect on hepatic steatosis in mice. Collectively, this study revealed the improvements of hyperlipidemia in mice by the synergistic effects of JSRS and B. pseudolongum, which will help in the development of "synbiotics" for the treatment of hyperlipidemia in the future.

Melatonin Regulates the Neurotransmitter Secretion Disorder Induced by Caffeine Through the Microbiota-Gut-Brain Axis in Zebrafish (Danio rerio).

Melatonin has been widely used as a "probiotic agent" capable of producing strong neurotransmitter secretion regulatory effects, and the microbiota-gut-brain axis-related studies have also highlighted the role of the gut microbiota in neuromodulation. In the present study, a zebrafish neural hyperactivity model was established using caffeine induction to explore the regulatory effects of melatonin and probiotic on neurotransmitter secretion disorder in zebrafish. Disorders of brain neurotransmitter secretion (dopamine, γ-aminobutyric acid, and 5-hydroxytryptamine) caused by caffeine were improved after interference treatment with melatonin or probiotic. Shotgun metagenomic sequencing demonstrated that the melatonin-treated zebrafish gradually restored their normal intestinal microbiota and metabolic pathways. Germ-free (GF) zebrafish were used to verify the essential role of intestinal microbes in the regulation of neurotransmitter secretion. The results of the neurotransmitter and short-chain fatty acid determination revealed that the effect on the zebrafish in the GF group could not achieve that on the zebrafish in the melatonin group after adding the same dose of melatonin. The present research revealed the potential mode of action of melatonin through the microbiota-gut-brain axis to regulate the disruption of neurotransmitter secretion, supporting the future development of psychotropic drugs targeting the intestinal microbiota.

The effects of exopolysaccharides and exopolysaccharide-producing Lactobacillus on the intestinal microbiome of zebrafish (Danio rerio).

BACKGROUND: Numerous studies have reported the health-promoting effects of exopolysaccharides (EPSs) in in vitro models; however, a functional evaluation of EPSs will provide additional knowledge of EPS-microbe interactions by in vivo intestinal microbial model. In the present study, high-throughput amplicon sequencing, short-chain fatty acid (SCFAs) and intestinal inflammation evaluation were performed to explore the potential benefits of exopolysaccharides (EPSs) and EPS-producing Lactobacillus (HNUB20 group) using the healthy zebrafish (Danio rerio) model. RESULTS: The results based on microbial taxonomic analysis revealed that the abundance of four genera, Ochrobactrum, Sediminibacterium, Sphingomonas and Sphingobium, were increased in the control group in comparison to HNUB20 group. Pelomonas spp. levels were significantly higher and that of the genera Lactobacillus and Brachybacterium were significantly decreased in EPS group compared with control group. PICRUSt based functional prediction of gut microbiota metabolic pathways indicated that significantly lower abundance was found for transcription, and membrane transport, whereas folding, sorting and degradation and energy metabolism had significantly higher abundance after HNUB20 treatment. Two metabolic pathways, including metabolism and endocrine functions, were more abundant in the EPS group than control group. Similar to the HNUB20 group, transcription was also decreased in the EPS group compared with the control group. However, SCFAs and immune indexes indicated EPS and HNUB20 performed limited efficacy in the healthy zebrafish. CONCLUSIONS: The present intestinal microbial model-based study indicated that EPSs and high-yield EPS-producing Lactobacillus can shake the structure of intestinal microbiota, but cannot change SCFAs presence and intestinal inflammation.