Reuteri Strains Research Articles

Coupled Effect of Nutritional Food Molecules and Lactobacillus reuteri Surface Protein Interaction on the Bacterial Gastrointestinal Tolerance.

Lactobacillus reuteri, which is present in fermented foods, can produce LPxTG motif proteins (LMPs) to help the strain resist gastrointestinal fluid environmental stress and enhance the adherence and colonizing properties. Intestinal nutrient small molecules can interact with LMPs and cooperate with Lactobacillus to exert probiotic effects in the host intestine. However, the mechanism of their correlation with gastrointestinal tolerance needs to be further studied. In this study, different kinds of nutritional food molecules, such as intestinal phenols, sugars, and acids, were screened and the interaction between the LPxTG proteins and small molecules was explored via the molecular docking approach. The docking results showed that phenols and oligosaccharides were more likely to bind to the LPxTG protein (B3XKV5), with the benzene ring, phenolic hydroxyl group, and glycosidic bond in the small molecule more easily binding to the active site of B3XKV5. Furthermore, the gastrointestinal tolerance was enhanced under the rutin, myricetin, quercetin phenols, and stachyose-treated L. reuteri strain groups, especially the phenol group, which revealed the relationship between the molecular interaction of the strain with the small molecules and strain tolerance mechanism. All the findings illustrated the gastrointestinal tolerance escape effect of the Lactobacillus strain under enriched intestinal nutrient small molecular conditions, and they also provide insight regarding the small molecules for the Lactobacillus strain under abnormal growth environments.

Development of a Limosilactobacillus reuteri therapeutic delivery platform with reduced colonization potential.

Bacterial biotherapeutic delivery vehicles have the potential to treat a variety of diseases. This approach obviates the need to purify the recombinant effector molecule, allows delivery of therapeutics in situ via oral or intranasal administration, and protects the effector molecule during gastrointestinal transit. Lactic acid bacteria have been broadly developed as therapeutic delivery vehicles though risks associated with the colonization of a genetically modified microorganism have so-far not been addressed. Here, we present an engineered Limosilactobacillus reuteri strain with reduced colonization potential. We applied a dual-recombineering scheme for efficient barcoding and generated mutants in genes encoding five previously characterized and four uncharacterized putative adhesins. Compared with the wild type, none of the mutants were reduced in their ability to survive gastrointestinal transit in mice. CmbA was identified as a key protein in L. reuteri adhesion to HT-29 and enteroid cells. The nonuple mutant, a single strain with all nine genes encoding adhesins inactivated, had reduced capacity to adhere to enteroid monolayers. The nonuple mutant producing murine IFN-β was equally effective as its wild-type counterpart in mitigating radiation toxicity in mice. Thus, this work established a novel therapeutic delivery platform that lays a foundation for its application in other microbial therapeutic delivery candidates and furthers the progress of the L. reuteri delivery system towards human use.IMPORTANCEOne major advantage to leverage gut microbes that have co-evolved with the vertebrate host is that evolution already has taken care of the difficult task to optimize survival within a complex ecosystem. The availability of the ecological niche will support colonization. However, long-term colonization of a recombinant microbe may not be desirable. Therefore, strategies need to be developed to overcome this potential safety concern. In this work, we developed a single strain in which we inactivated the encoding sortase, and eight genes encoding characterized/putative adhesins. Each individual mutant was characterized for growth and adhesion to epithelial cells. On enteroid cells, the nonuple mutant has a reduced adhesion potential compared with the wild-type strain. In a model of total-body irradiation, the nonuple strain engineered to release murine interferon-β performed comparable to a derivative of the wild-type strain that releases interferon-β. This work is an important step toward the application of recombinant L. reuteri in humans.

Probiotics and Other Supplements for Autism Spectrum Disorder (ASD): A Comprehensive Review

Introduction: Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition characterized by social interaction challenges, communication difficulties, and repetitive behaviors. While ASD lacks a cure, there is a growing interest in supplements, notably probiotics, for potential benefits. Probiotics are live microorganisms with health potential due to their role in the gut microbiome. Gut-brain axis is a bi-directional communication system that connects the gastrointestinal (GI) tract and the brain. Objective: This comprehensive review systematically searched scientific databases up to September 2023 to examine the use of supplements, particularly probiotics, in individuals with ASD. The review focused on addressing gut-related issues and improving behavior, speech, and overall well-being. Methods: A systematic search across databases such as PubMed, PsycINFO, and Cochrane library was conducted using keywords like "probiotics," "supplements," "ASD," "gut dysbiosis," and "therapeutic interventions." Studies meeting inclusion criteria, including clinical trials, observational studies, and case reports, were considered. Results: Several studies suggest that probiotics may improve behavior, brain activity, and eye contact in individuals with ASD by addressing gut dysbiosis. Lactobacillus reuteri and specific Bifidobacterium strains are recommended probiotics, but more research is needed to confirm their efficacy. This review also explores supplements like Vitamin B6, magnesium, Vitamin B12, Vitamin C, and Omega-3 fatty acids, which show potential in supporting speech and overall well-being in individuals with ASD. However, they are not a cure and should be used under professional guidance. The article also discusses supplements for adults with ASD, underlining the importance of consulting healthcare professionals before use and the necessity for further research to determine effectiveness and optimal dosages. Conclusion: Probiotics and supplements offer potential benefits for individuals with ASD, but they should be seen as complementary therapies rather than cures. A holistic approach, including medical supervision, therapy, and dietary considerations, is crucial for addressing the complex needs of individuals with ASD. Further research is necessary to uncover the precise mechanisms and therapeutic potential of these supplements in enhancing the lives of those with ASD. Categories: Neurology, Gastroenterology, Nutrition

Glycerol-derived reuterin regulates human intestinal microbiota and metabolites.

Reuterin, a mixture of different forms of 3-hydroxypropanal (3-HPA), including HPA hydrate and HPA dimer, is an antimicrobial compound converted from glycerol by Lactobacillus reuteri and other strains. Although its antimicrobial function may be related to its interaction with thiol groups, its temperature stability and effect on the gut environment remain unclear. The present study evaluated the antimicrobial effects and activity of reuterin against Escherichia coli and Salmonella typhimurium. Utilization of a reliable in vitro gut microbiome fermentation system revealed that reuterin has a modulatory effect on the gut microbial community. Reuterin treatment completely inhibited H2 and NH3 production in the gut and significantly enhanced the synthesis of branched short-chain fatty acids. 16s rRNA sequencing indicated that reuterin promoted the growth of Proteobacteria and Bacteroidetes in the in vitro system and significantly modulated gut microbiota composition.

Limosilactobacillus reuteri Alleviates Anxiety-like Behavior and Intestinal Symptoms in Two Stressed Mouse Models.

Limosilactobacillus (Lm.) reuteri is a widely utilized probiotic, recognized for its significant role in alleviating symptoms associated with gastrointestinal and psychiatric disorders. However, the effectiveness of Lm. reuteri is strain-specific, and its genetic diversity leads to significant differences in phenotypes among different strains. This study aims to identify potential probiotic strains by comparing the strain-specific characteristics of Lm. reuteri to better understand their efficacy and mechanisms in alleviating stress-induced anxiety-like behaviors and gastrointestinal symptoms. We cultivated 11 strains of Lm. reuteri from healthy human samples and conducted phenotypic and genomic characterizations. Two strains, WLR01 (=GOLDGUT-LR99) and WLR06, were screened as potential probiotics and were tested for their efficacy in alleviating anxiety-like behavior and intestinal symptoms in mouse models subjected to sleep deprivation (SD) and water avoidance stress (WAS). The results showed that the selected strains effectively improved mouse behaviors, including cognitive impairment and inflammatory response, as well as improving anxiety and regulating gut microbiota composition. The improvements with WLR01 were associated with the regulation of the NLRP3 inflammasome pathway in the SD model mice and were associated with visceral hypersensitivity and intestinal integrity in the WAS model mice. In summary, this study identified the Lm. reuteri strain WLR01 as having the potential to alleviate anxiety-like behavior and intestinal symptoms through the analysis of Lm. reuteri genotypes and phenotypes, as well as validation in mouse models, thereby laying the foundation for future clinical applications.

Highly accurate and sensitive absolute quantification of bacterial strains in human fecal samples

BackgroundNext-generation sequencing (NGS) approaches have revolutionized gut microbiome research and can provide strain-level resolution, but these techniques have limitations in that they are only semi-quantitative, suffer from high detection limits, and generate data that is compositional. The present study aimed to systematically compare quantitative PCR (qPCR) and droplet digital PCR (ddPCR) for the absolute quantification of Limosilactobacillus reuteri strains in human fecal samples and to develop an optimized protocol for the absolute quantification of bacterial strains in fecal samples.ResultsUsing strain-specific PCR primers for L. reuteri 17938, ddPCR showed slightly better reproducibility, but qPCR was almost as reproducible and showed comparable sensitivity (limit of detection [LOD] around 104 cells/g feces) and linearity (R2 > 0.98) when kit-based DNA isolation methods were used. qPCR further had a wider dynamic range and is cheaper and faster. Based on these findings, we conclude that qPCR has advantages over ddPCR for the absolute quantification of bacterial strains in fecal samples. We provide an optimized and easy-to-follow step-by-step protocol for the design of strain-specific qPCR assays, starting from primer design from genome sequences to the calibration of the PCR system. Validation of this protocol to design PCR assays for two L. reuteri strains, PB-W1 and DSM 20016 T, resulted in a highly accurate qPCR with a detection limit in spiked fecal samples of around 103 cells/g feces. Applying our strain-specific qPCR assays to fecal samples collected from human subjects who received live L. reuteri PB-W1 or DSM 20016 T during a human trial demonstrated a highly accurate quantification and sensitive detection of these two strains, with a much lower LOD and a broader dynamic range compared to NGS approaches (16S rRNA gene sequencing and whole metagenome sequencing).ConclusionsBased on our analyses, we consider qPCR with kit-based DNA extraction approaches the best approach to accurately quantify gut bacteria at the strain level in fecal samples. The provided step-by-step protocol will allow scientists to design highly sensitive strain-specific PCR systems for the accurate quantification of bacterial strains of not only L. reuteri but also other bacterial taxa in a broad range of applications and sample types.-oGjUmj5e8MXZDxyDjzcm-Video

Limosilactobacillus reuteri promotes the expression and secretion of enteroendocrine- and enterocyte-derived hormones.

Observations that intestinal microbes can beneficially impact host physiology have prompted investigations into the therapeutic usage of such microbes in a range of diseases. For example, the human intestinal microbe Limosilactobacillus reuteri strains ATCC PTA 6475 and DSM 17938 are being considered for use for intestinal ailments including colic, infection, and inflammation as well as non-intestinal ailments including osteoporosis, wound healing, and autism spectrum disorder. While many of their beneficial properties are attributed to suppressing inflammatory responses in the gut, we postulated that L. reuteri may also regulate hormones of the gastrointestinal tract to affect physiology within and outside of the gut. To determine if L. reuteri secreted factors impact the secretion of enteric hormones, we treated an engineered jejunal organoid line, NGN3-HIO, which can be induced to be enriched in enteroendocrine cells, with L. reuteri 6475 or 17938 conditioned medium and performed transcriptomics. Our data suggest that these L. reuteri strains affect the transcription of many gut hormones, including vasopressin and luteinizing hormone subunit beta, which have not been previously recognized as being produced in the gut epithelium. Moreover, we find that these hormones appear to be produced in enterocytes, in contrast to canonical gut hormones which are produced in enteroendocrine cells. Finally, we show that L. reuteri conditioned media promotes the secretion of several enteric hormones including serotonin, GIP, PYY, vasopressin, and luteinizing hormone subunit beta. These results support L. reuteri affecting host physiology through intestinal hormone secretion, thereby expanding our understanding of the mechanistic actions of this microbe.

Effects of Limosilactobacillus reuteri strains PTA-126787 and PTA-126788 on intestinal barrier integrity and immune homeostasis in an alcohol-induced leaky gut model

Intestinal barrier is a first line of defense that prevents entry of various harmful substances from the lumen into the systemic environment. Impaired barrier function with consequent translocation of harmful substances into systemic circulation (“leaky gut”) is a central theme in many gastrointestinal, autoimmune, mental, and metabolic diseases. Probiotics have emerged as a promising strategy to maintain intestinal integrity and address “leaky gut”. Using in silico, in vitro and avian in vivo analyses, we previously showed that two novel L. reuteri strains, PTA-126787 (L. reuteri 3630) and PTA-126788 (L. reuteri 3632), isolated from broiler chickens possess favorable safety profiles. Consistent with a recent study, here we show that L. reuteri 3630 and 3632 are phylogenetically similar to human L. reuteri strains. Daily administration of high doses of L. reuteri 3630 and 3632 to Sprague Dawley rats for 28 days was found to be safe with no adverse effects. More importantly, administration of L. reuteri 3630 and 3632 significantly reduced markers associated with alcohol-induced leaky gut, by downregulating inflammatory cytokines and upregulating anti-inflammatory cytokines in an alcohol model of leaky gut in mice. While L. reuteri 3630 cells and supernatant showed no activation, L. reuteri 3632 cells but not supernatant showed activation of AhR, a key transcription factor that regulates gut and immune homeostasis. L. reuteri 3630 is creamish white in morphology typical of Lactobacillus species and L. reuteri 3632 displays a unique orange pigmentation, which was stable even after passaging for 480 generations. We identified a rare polyketide biosynthetic gene cluster in L. reuteri 3632 that likely encodes for the orange-pigmented secondary metabolite. Similar to L. reuteri 3632 cells, the purified orange metabolite activated AhR. All together, these data provide evidence on the phylogenetic relatedness, safety, efficacy, and one of the likely mechanisms of action of L. reuteri 3630 and 3632 for potential probiotic applications to address “leaky gut” and associated pathologies in humans.

Gut microbiota metabolite indole-3-acetic acid maintains intestinal epithelial homeostasis through mucin sulfation

ABSTRACT The global incidence and prevalence of inflammatory bowel disease (IBD) are gradually increasing. A high-fat diet (HFD) is known to disrupt intestinal homeostasis and aggravate IBD, yet the underlying mechanisms remain largely undefined. Here, a positive correlation between dietary fat intake and disease severity in both IBD patients and murine colitis models is observed. A HFD induces a significant decrease in indole-3-acetic acid (IAA) and leads to intestinal barrier damage. Furthermore, IAA supplementation enhances intestinal mucin sulfation and effectively alleviates colitis. Mechanistically, IAA upregulates key molecules involved in mucin sulfation, including 3’-phosphoadenosine 5’-phosphosulfate synthase 2 (Papss2) and solute carrier family 35 member B3 (Slc35b3), the synthesis enzyme and the transferase of 3’-phosphoadenosine-5’-phosphosulfate (PAPS), via the aryl hydrocarbon receptor (AHR). More importantly, AHR can directly bind to the transcription start site of Papss2. Oral administration of Lactobacillus reuteri, which can produce IAA, contributes to protecting against colitis and promoting mucin sulfation, while the modified L. reuteri strain lacking the iaaM gene (Lactobacillus ΔiaaM ) and the ability to produce IAA fail to exhibit such effects. Overall, IAA enhances intestinal mucin sulfation through the AHR-Papss2-Slc35b3 pathway, contributing to the protection of intestinal homfeostasis.

Effects of Limosilactobacillus reuteri ID-D01 Probiotic Supplementation on Exercise Performance and Gut Microbiota in Sprague-Dawley Rats.

The gut microbiota composition in animals and humans has recently been found to be influenced by exercise. Although Limosilactobacillus reuteri strains have notable probiotic properties that promote human health, understanding of its effects in combination with exercise and physical activity is limited. Therefore, this study examined the effects of L. reuteri ID-D01, a human-derived probiotic, on exercise performance and fatigue in Sprague-Dawley rats. Organ weight, maximal running distance, serum biochemistry, muscle performance, microbial community composition, and short-chain fatty acid (SCFA) levels were assessed. Results indicated that ID-D01 supplementation significantly improved endurance performance. Rats in the probiotic group demonstrated a significant increase in maximal running distance compared with that in the control group (p < 0.05). Additionally, levels of fatigue markers, such as lactate and creatine phosphokinase, were significantly reduced in the ID-D01-administered groups, suggesting its potential to alleviate exercise-induced fatigue. Microbiome analysis revealed a distinct shift in gut microbiota composition in response to ID-D01 administration. The group that received ID-D01 probiotics exhibited a significant increase in the abundance of SCFA-producing bacteria, particularly Akkermansia spp., compared with that in the control groups. Furthermore, they showed elevated production of SCFAs, such as acetate and butyrate. In conclusion, this study demonstrated that ID-D01 can enhance exercise performance and reduce fatigue. Herein, we highlighted that human-derived probiotics could improve physical performance, as observed by changes in gut microbiota composition and SCFA production.

Complete genome sequences of Lactobacillus acidophilus strain P42 and Limosilactobacillus reuteri strain P43 isolated from chicken cecum.

The gut microflora contains a diverse microbial population that is influenced by the host and the environment. We report the complete circular genome sequences of Lactobacillus acidophilus strain P42 and Limosilactobacillus reuteri strain P43 isolated from chicken cecal samples. P42 and P43 could potentially serve as poultry probiotic strains.

Whole genome sequencing analysis of Limosilactobacillus reuteri from the intestinal tract of mice recovering from ulcerative colitis and preliminary study on anti-inflammatory effects of its derived peptides.

Limosilactobacillus reuteri is an indigenous inhabitant of the animal gut known for its probiotic effects on the host. In our previous study, a large number of L. reuteri strains were isolated from the gastrointestinal tract of mice recovering from ulcerative colitis, from which we randomly selected L. reuteri RE225 for whole genome sequencing to explore its probiotic properties. The results of next-generation sequencing and third-generation single molecule sequencing showed that L. reuteri RE225 contained many genes encoding functional proteins associated with adhesion, anti-inflammatory and pathogen inhibition. And compared to other L. reuteri strains in NCBI, L. reuteri RE225 has unique gene families with probiotic functions. In order to further explore the probiotic effect of the L. reuteri RE225, the derived peptides were identified by LC-MS/MS, and the peptides with tumor necrosis factor-α binding ability were screened by reverse molecular docking and microscale thermophoresis. Finally, cell experiments demonstrated the anti-inflammatory ability of the peptides. Western blotting and qPCR analyses confirmed that the selected peptides might alleviate LPS-induced inflammation in NCM460 cells by inhibiting JAK2/STAT3 pathway activation.

Intestinal microbiota features of children born by cesarean section and its correction

Introduction. Studying the gut microbiota of C-section newborns and its correction is a topical problem at present.Aim. To study the process of gut microbiota formation in healthy C-section infants, and the option for its correction using a Lactobacillus reuteri strain DSM 17938 probiotic.Materials and methods. A total of 80 healthy newborns were included in the study. Of these, 59 completed the study: the treatment group consisted of 36 elective caesarean (EC)-section infants and the control group was made up of 23 vaginally delivered infants. Newborns of the treatment study group were randomized into subgroups, one of which received the L. reuteri strain DSM 17938 (L subgroup) probiotic, and the second one did not receive it (0 subgroup). During the entire period of the study, infants were exclusively breastfed. The gut microbiota was analysed with the 16S rRNA sequencing method, and the metabolic activity of the gut microbiota was additionally assessed using gas-liquid chromatography.Results and discussion. The metagenomic analysis showed that the taxonomic richness and biological diversity of the gut microbiota in L subgroup infants increased in time interval 3, which indicated the active effect of the strain on the infant microbiota by Exposure Day 30. The gas-liquid chromatography analysis showed more pronounced changes in short-chain fatty acids in infants of the L subgroup: they were more similar to the findings in the control group (vaginal delivery). Also, bowel problems and allergies occurred less frequently in infants of this subgroup and they less frequently suffered from respiratory diseases during the year. The study showed the association between the mode of delivery and changes in anthropometric measurements.Conclusion. The use of L. reuteri strain DSM 17938 probiotic had a significant effect on the formation of the microbiota by the 30th day of age. A daily long-term addition of a L. reuteri strain DSM 17938 probiotic can prevent early microbiota dysbiosis and have a protective effect in later age period.

Analysis of the key genes of Lactobacillus reuteri strains involved in the protection against alcohol-induced intestinal barrier damage.

Gastrointestinal inflammation and intestinal barrier function have important effects on human health. Alcohol, an important foodborne hazard factor, damages the intestinal barrier, increasing the risk of disease. Lactobacillus reuteri strains have been reported to reduce gastrointestinal inflammation and strengthen the intestinal barrier. In this study, we selected three anti-inflammatory L. reuteri strains to evaluate their role in the protection of the intestinal barrier and their immunomodulatory activity in a mouse model of gradient alcohol intake. Among the three strains tested (FSCDJY33M3, FGSZY33L6, and FCQHCL8L6), L. reuteri FSCDJY33M3 was found to protect the intestinal barrier most effectively, possibly due to its ability to reduce the expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) and increase the expression of tight junction proteins (occludin, claudin-3). Genomic analysis suggested that the protective effects of L. reuteri FSCDJY33M3 may be related to functional genes and glycoside hydrolases associated with energy production and conversion, amino acid transport and metabolism, carbohydrate transport and metabolism, and DNA replication, recombination, and repair. These genes include COG2856, COG1804, COG2071, and COG1061, which encode adenine deaminase, acyl-CoA transferases, glutamine amidotransferase, RNA helicase, and glycoside hydrolases, including GH13_20, GH53, and GH70. Our results identified functional genes that may be related to protection against alcohol-induced intestinal barrier damage, which might be useful for screening lactic acid bacterial strains that can protect the intestinal barrier.

IL-6 expression-suppressing Lactobacillus reuteri strains alleviate gut microbiota-induced anxiety and depression in mice.

Fecal microbiota transplantation from patients with depression/inflammatory bowel disease (PDI) causes depression with gut inflammation in mice. Here, we investigated the effects of six Lactobacillus reuteri strains on brain-derived neurotropic factor (BDNF), serotonin, and interleukin (IL)-6 expression in neuronal or macrophage cells and PDI fecal microbiota-cultured microbiota (PcM)-induced depression in mice. Of these strains, L6 most potently increased BDNF and serotonin levels in corticosterone-stimulated SH-SY5Y and PC12 cells, followed by L3. L6 most potently decreased IL-6 expression in lipopolysaccharide (LPS)-stimulated macrophages. When L1 (weakest in vitro), L3, and L6 were orally administered in mice with PcM-induced depression, L6 most potently suppressed depression-like behaviors and hippocampal TNF-α and IL-6 expression and increased hippocampal serotonin, BDNF, 5HT7, GABAARα1, and GABABR1b expression, followed by L3 and L1. L6 also suppressed TNF-α and IL-6 expression in the colon. BDNF or serotonin levels in corticosterone-stimulated neuronal cells were negatively correlated with depression-related biomarkers in PcM-transplanted mice, while IL-6 levels in LPS-stimulated macrophage were positively correlated. These findings suggest that IL-6 expression-suppressing and BDNF/serotonin expression-inducing LBPs in vitro, particularly L6, may alleviate gut microbiota-involved depression with colitis in vivo.

Microencapsulated Limosilactobacillus reuteri Encoding Lactoferricin-Lactoferrampin Targeted Intestine against Salmonella typhimurium Infection.

Salmonella enterica serovar Typhimurium (S. typhimurium) is an important foodborne pathogen that infects both humans and animals and develops acute gastroenteritis. As porcine intestines are relatively similar to the human ones due to their relatively similar sizes and structural similarity, S. typhimurium causes analogous symptoms in both. Novel strategies for controlling S. typhimurium infection are also desired, such as mucosal-targeted delivery of probiotics and antimicrobial peptides. The bovine lactoferricin-lactoferrampin-encoding Limosilactobacillus reuteri (LR-LFCA) strain improves intestinal barrier function by strengthening the intestinal barrier. Weaned piglets were selected for oral administration of microencapsulated LR-LFCA (microcapsules entrap LR-LFCA into gastro-resistant polymers) and then infected with S. typhimurium for 3 days. We found that orally administering microencapsulated LR-LFCA to weaned piglets attenuated S. typhimurium-induced production of inflammatory factors in the intestinal mucosa by inhibiting the nuclear factor-kappa B (NF-κB) and P38 mitogen-activated protein kinases (MAPK) signaling pathway. Moreover, microencapsulated LR-LFCA administration significantly suppressed the oxidative stress that may correlate with gut microbiota (reduced Salmonella population and increased α-diversity and Lactobacillus abundance) and intestinal function (membrane transport and metabolism). Our work demonstrated that microencapsulated LR-LFCA effectively targeted intestine delivery of Lactobacillus and antimicrobial peptides and modulated gut microbiota and mucosal immunity. This study reveals a novel targeting mucosal strategy against S. typhimurium infection.

Rhizospheric Lactobacillus spp. contribute to the high Cd-accumulating characteristics of Phytolacca spp. in acidic Cd-contaminated soil

Screening high Cd-accumulating plants and understanding the interactions between plants, rhizospheric microbes and Cd are important in developing microbe-assisted phytoremediation techniques for Cd-contaminated soils. In this study, the Cd tolerance and accumulation characteristics of Phytolacca americana L., P. icosandra L. and P. polyandra Batalin growing in acidic Cd-contaminated soil were compared to evaluate their phytoremediation potential. According to Cd concentrations (root: 8.26–37.09 mg kg−1, shoot: 2.80–9.26 mg kg−1), bioconcentration factors (BCFs) and translocation factors (TFs), the three Phytolacca species exhibited high Cd-accumulation capacities, ranked in the following order: P. icosandra (root BCF: 1.25, shoot BCF: 0.31, TF: 0.25) > P. polyandra (root BCF: 0.68, shoot BCF: 0.26, TF: 0.44) > P. americana (root BCF: 0.28, shoot BCF: 0.09, TF: 0.38). Phytolacca icosandra and P. polyandra can thus be considered as two new Cd accumulators for phytoremediation. Soil pH, available Cd (ACd) concentration and certain bacterial taxa (e.g. Lactobacillus, Helicobacter, Alistipes, Desulfovibrio and Mucispirillum) were differentially altered in the rhizospheres of the three Phytolacca species in comparison to unplanted soil. Correlation analysis showed that there were significant interactions between rhizospheric ACd concentration, pH and Lactobacillus bacteria (L. murinus, L. gasseri and L. reuteri), which affected Cd uptake by Phytolacca plants. The mono- and co-inoculation of L. murinus strain D51883, L. gasseri strain D51533 and L. reuteri strain D24591 in the rhizosphere of P. icosandra altered the rhizospheric pH and ACd concentrations, in addition to increasing the shoot Cd contents by 31.9%–44.6%. These results suggest that recruitment of rhizospheric Lactobacillus spp. by Phytolacca plants contributes to their high Cd-accumulating characteristics. This study provides novel insights into understanding the interactions between plants, rhizobacteria and heavy metals.

Construction of prophage-free and highly-transformable Limosilactobacillus reuteri strains and their use for production of 1,3-propanediol.

The lactic acid bacterium Limosilactobacillus reuteri (formerly Lactobacillus reuteri) is a desirable host for the production of 1,3-propanediol (1,3-PDO) from glycerol when 1,3-PDO is used in the food or cosmetic industry. However, the production is hindered by strain instability, causing cell lysis, and difficult gene manipulation. This study reveals that the stability of L. reuteri DSM 20016 and its 1,3-PDO production, especially in the alcohol dehydrogenases (ADHs)-deletion mutants, are greatly enhanced after the deletion of two prophages (Φ3 and Φ4) present in the L. reuteri's chromosome. The resulting phage-free and ADHs-deletion mutant could produce >825 mM 1,3-PDO in 48 h without cell lysis at the theoretical maximum yield on glucose of ~2 mol/mol. Compared to the wild-type strain, the mutant exhibited a 45.2% increase in 1,3-PDO production titer and a 2.1-fold increase in yield. In addition, this study reports that the transformation efficiency of L. reuteri Δadh2Δadh6 mutant strains were greatly enhanced by >300-fold after the deletion of prophage Φ3, probably due to the removal of a restriction-modification (RM) system which resides in the phage genome. With improved stability and higher transformation efficiency, recombinant L. reuteri DSM 20016 Δadh2Δadh6ΔΦ3ΔΦ4 can be a more reliable and amenable host for industrial applications.

Bioluminescent monitoring of recombinant lactic acid bacteria and their products.

Lactic acid bacteria constitute a genetically diverse group of microorganisms with significant roles in the food industry, biotechnology, agriculture, and medicine. A core understanding of bacterial physiology in diverse environments is crucial to select and develop bacteria for industrial and medical applications. However, there is a lack of versatile tools to track (recombinant) protein production in lactic acid bacteria. In this study, we adapted a peptide-based bioluminescent tagging system that is functional across multiple genera and species. This system enables tracking of tagged proteins both in vitro and in situ, while it also can be used to enumerate recombinant bacteria from the mouse gastrointestinal tract with accuracy comparable to that of conventional plate counts. Our work expands the lactic acid bacteria genetic toolbox and will facilitate researchers in industry and academia with opportunities to monitor microbes and proteins under different physiologically relevant conditions.

Lactobacillus reuteri in digestive system diseases: focus on clinical trials and mechanisms.

Digestive system diseases have evolved into a growing global burden without sufficient therapeutic measures. Lactobacillus reuteri (L. reuteri) is considered as a new potential economical therapy for its probiotic effects in the gastrointestinal system. We have provided an overview of the researches supporting various L. reuteri strains' application in treating common digestive system diseases, including infantile colic, diarrhea, constipation, functional abdominal pain, Helicobacter pylori infection, inflammatory bowel disease, diverticulitis, colorectal cancer and liver diseases. The summarized literature in this review was derived from databases including PubMed, Web of Science, and Google Scholar. The therapeutic effects of L. reuteri in digestive system diseases may depend on various direct and indirect mechanisms, including metabolite production as well as modulation of the intestinal microbiome, preservation of the gut barrier function, and regulation of the host immune system. These actions are largely strain-specific and depend on the activation or inhibition of various certain signal pathways. It is well evidenced that L. reuteri can be effective both as a prophylactic measure and as a preferred therapy for infantile colic, and it can also be recommended as an adjuvant strategy to diarrhea, constipation, Helicobacter pylori infection in therapeutic settings. While preclinical studies have shown the probiotic potential of L. reuteri in the management of functional abdominal pain, inflammatory bowel disease, diverticulitis, colorectal cancer and liver diseases, its application in these disease settings still needs further study. This review focuses on the probiotic effects of L. reuteri on gut homeostasis via certain signaling pathways, and emphasizes the importance of these probiotics as a prospective treatment against several digestive system diseases.