Genus Parabacteroides Research Articles

Parabacteroides faecalis sp. nov. Isolated from Swine Faeces.

A Gram-negative, obligate anaerobic, non-motile, non-spore-forming, rod-shaped bacterial strain designated AGMB00274T was isolated from swine faeces. An 16S rRNA gene analysis indicated that strain AGMB00274T belonged to the genus Parabacteroides, with the highest similarity to Parabacteroides johnsonii (P. johnsonii) DSM 18315T (sequence similarity of 94.9%). The genome size of strain AGMB00274T was 4,308,683bp, with a DNA G+C content of 42.5mol%. The biochemical analysis of strain AGMB00274T showed that it was positive for gelatin hydrolysis and α-fucosidase, but negative for the acid production from D-glucose, D-mannitol, D-maltose, salicin, glycerol, D-cellobiose, D-mannose, D-melezitose, D-sorbitol, D-trehalose, and negative for α-arabinosidase, glutamic acid decarboxylase, and pyroglutamic acid arylamidase. The dominant cellular fatty acids (> 10%) of the isolate were anteiso-C15: 0 (23.2%), iso-C15: 0 (16.6%), C18: 1 ω9c (16.4%), summed feature 11 (iso-C17: 0 3-OH and/or C18: 2 DMA) (12.5%), and C16: 0 (11.3%). The major respiratory quinones of strain AGMB00274T were MK-9 (55.4%) and MK-10 (44.6%). The major polar lipid was phosphatidylethanolamine. Based on phylogenetic, genetic, physiological, and chemotaxonomic analyses, as a novel species of the genus Parabacteroides, strain AGMB00274T was proposed with the name Parabacteroides faecalis sp. nov. The type strain used was AGMB00274T (= KCTC 25286T = GDMCC 1.2742T).

Cellulose Butyrate as a Potent Fiber Supplement for Mono-Gastric Animals to Modulate Hindgut Microbiota and Fermentation: In Vitro Evaluations

To evaluate the function of cellulose butyrate (CB), a new synthetic, fibrous, candidate food additive, a series of batch culture study was carried out. Fecal cultures were prepared using fresh feces from human volunteers and swines, and anaerobically incubated to characterize the effect of CB on hindgut fermentation and microbial community, and thereby evaluate the potential use of CB as a food additive in mono-gastric animals. Three types of CB differing in the degree of substitution and in the carbon position of glucose residue where butyl groups are substituted were tested to proceed multiple comparisons for measured parameters. Among three types of CB tested, partially water-soluble CB3 was associated with the highest increase in butyrate production in human and swine fecal cultures. CB3 supplementation shifted fecal microbiota toward greater abundance of bacteria in the Bacteroidetes phylum, in particular the genus Parabacteroides, in which the increase of Parabacteroides distasonis was remarkable even with individual variations. CB3 also lowered putrefactive products, including ammonia, indole and skatole, in the cultures. Dietary use of partially water-soluble CB3 might be expected to have useful effects in humans and other mono-gastric animals, judging from the present results of enhanced butyrate production and lowered putrefactive products with CB3 addition to feces. The results might be partly attributable to a shift in hindgut microbiota, represented by the increased abundance of Bacteroidetes, especially Parabacteroides species. Therefore, CB3 can be considered as a functional additive candidate for the use in mono-gastric animals such as human and pigs.

The Auxiliary Effects of Low-Molecular-Weight Fucoidan in Locally Advanced Rectal Cancer Patients Receiving Neoadjuvant Concurrent Chemoradiotherapy Before Surgery: A Double-Blind, Randomized, Placebo-Controlled Study.

Patients with cancer use low-molecular-weight fucoidan (LMF) as a supplement to therapy. However, most studies of LMF are in vitro or conducted using animals. Concurrent chemoradiotherapy (CCRT) is the gold standard for locally advanced rectal cancer (LARC). This study investigated the quality of life (QoL) and clinical outcomes of patients with LARC taking LMF as a supplement to neoadjuvant CCRT. This was a double-blind, randomized, placebo-controlled study. The sample comprised 87 patients, of whom 44 were included in a fucoidan group and 43 were included in a placebo group. We compared their QoL scores and clinical outcomes before treatment, and at 1 month, 2 months, and 3 months posttreatment. Pretreatment and posttreatment gut microbiota differences were also compared. Although enhanced physical well-being (PWB) at 2 months and 3 months posttreatment in the fucoidan group were observed (both P < .0125), the improvements of the Functional Assessment of Cancer Therapy for Patients with Colorectal Cancer (FACT-C) were nonsignificant (all P > .0125). Skin rash and itching and fatigue were less common in the fucoidan group (both P < .05). Posttreatment, the genus Parabacteroides was significantly more common in the gut microbiota of the fucoidan group. LMF administration improved the QoL, skin rash and itching, fatigue, and gut microbiota composition of the patients with LARC receiving CCRT.Clinical Trial Registration: NCT04342949.

Effects of Dietary Quinoa Seeds on Cecal Microorganisms and Muscle Fatty Acids of Female Luhua Chickens.

To study the effects of adding quinoa seed (raw grain) to the diet of the Luhua chicken on the cecal microorganism abundance and fatty acid composition of muscle, 120 49-day-old healthy female dewormed Luhua chickens (body weight 1476.21 ± 101.39 g) were randomly divided into 4 groups, with 3 replicates in each group and 10 chickens in each repetition. The control group (CK group) was fed a basal diet and the experimental groups were fed with 4% (Q4), 8% (Q8), and 12% (Q12) quinoa seed (raw grain) added to the basal diet for 75 days. After 121 days of age, the animals were slaughtered and the 16S rRNA characteristics of cecal flora, as well as composition and content of fatty acids in muscle, were determined and analyzed. The content of unsaturated fatty acids (UFAs), docosahexaenoic acid (C22:6n3; DHA) and n-3 polyunsaturated fatty acids (n-3 PUFAs) in the breast and leg muscles significantly increased in the experimental groups supplemented with quinoa seeds (p < 0.05). However, the content of saturated fatty acids (SAFs) and ratio of n-6/n-3 in breast muscle and leg muscle significantly decreased (p < 0.05). In addition, adding a certain percentage of quinoa seeds in the diet can also affect the community composition and content of microorganisms in the ceca of Luhua chickens. At the phylum level, the Proteobacteria, Actinobacteria, Synergistetes and Melainabacteria in experimental groups (Q4, Q8 and Q12) were significantly lower than those in the CK group (p < 0.05). At the genus level, Desulfovibrio, Synergistes, Olsenella, Parabacteroides, Mailhella, Sutterella and Ruminiclostridiu in group Q4 were significantly lower than those in group CK (p < 0.05) while Faecalibacterium in Q8 group, and Lawsonia and Faecalibacterium in Q12 group were significantly higher than those in the CK group (p < 0.05). Enrichment analysis of the microbial function showed that compared with the CK group, Metabolism and Enzyme Families were significantly enriched in the Q4 group (p < 0.05). Cellular Processes and Signaling were significantly enriched in the Q8 group (p < 0.05). The association analysis of fatty acids with microorganisms showed that the abundance of Faecalibacterium, Lawsonia and Meagmonas was significantly correlated with partial SFAs and UFAs (p < 0.05). In conclusion, adding quinoa seeds to diets significantly increased the content of muscle DHA, UFAs and n-3 PUFAs. The content of SAFs and the n-6/n-3 ratio were significantly reduced. Taken together, quinoa can effectively improve the cecal microbiota structure, inhibit the number of harmful bacteria and increase the number of beneficial bacteria, regulating the intestinal environment and promoting the body health of female Luhua chickens.

Alteration of gut microbiota in migraine patients with irritable bowel syndrome in a Chinese Han population.

Migraine is frequently reported in patients with irritable bowel syndrome (IBS), and emerging evidence suggests that gut microbiota plays a role in migraine and IBS. However, alterations in the gut microbiome in migraine patients with IBS remain unknown. This study aimed to explore the compositions of gut microbiota in migraine patients with IBS in a Chinese Han population. Sixteen migraine patients with IBS and thirteen age- and gender-matched IBS patients with similar dietary and lifestyle habits were enrolled in this pilot study. Demographic data, clinical data, eating habits, lifestyle habits, comorbidities, and medications were recorded using a unified case registration form. Questionnaires for the Migraine Disability Assessment (MIDAS), Pittsburgh Sleep Quality Index (PSQI), Hamilton Anxiety Scale (HAMA), and Hamilton Depression Scale (HAMD) were completed. Fecal samples were collected, and microbial DNA was extracted. Gut microbiota 16S ribosomal RNA (16S rRNA) gene sequencing targeting the V4 region was performed using the Illumina HiSeq 2500 high-throughput sequencing platform. The relationships between gut microbiota and clinical characteristics of migraine were analyzed. The structure of gut microbiota differed between migraine patients with IBS and patients with IBS, while the richness and diversity of gut microbiota in migraine patients with IBS showed no significant difference from that of patients with IBS. We found a higher relative abundance of the genus Parabacteroides and a lower relative abundance of the genera Paraprevotella, Lachnospiraceae_UCG-010, Lactococcus, Collinsella, and Comamonas in migraine patients with IBS than in patients with IBS. According to random forest predictive models, the phylum Bacteroidota shows the most important role in migraine patients with IBS. Furthermore, no statistical correlation was found between significantly different taxa at the genus level and migraine clinical data. This study identified that altered gut microbiota occurred in Chinese Han migraine patients with IBS, but no correlation was found between gut microbiota and the clinical characteristics of migraine. Further study is needed to better understand the role of gut microbiota in the pathogenesis of migraine in IBS.

Epidemiology and antibiotic susceptibility profiles of obligate anaerobes in a hospital of central Italy during a one-year (2019) survey

ObjectivesIn this study, we report on the epidemiology and susceptibility profiles of anaerobic pathogens consecutively isolated from various clinical samples at an Italian hospital during a one-year survey. MethodsThe collection included all non-duplicated consecutively collected anaerobic clinical isolates during 2019 in San Luca Hospital (Lucca, Italy). Antimicrobial susceptibility testing was performed using MICRONAUT-S Anaerobes MIC lyophilized plates (MERLIN Diagnostika, Germany) and interpreted using EUCAST criteria (11.0). ResultsA total of 169 Gram-negative and 213 Gram-positive were collected. The most frequent anaerobes were Bacteroides spp. (120, 31.4%) followed by Finegoldia magna (62, 16.2%). External ulcers were the most common source of isolates (39%), followed by blood (25.7%). In 230 patients (65%) polymicrobial aerobic/anaerobic isolates were cultured from the same external ulcer specimen. High resistance rates to clindamycin were overall detected, with the highest values among the genera Parabacteroides, Bacteroides, Prevotella, Gram-positive anaerobic cocci and Clostridium. High resistance rates were also observed to metronidazole among both Gram-positive and Gram-negative species, ranging between 10.8-50% and 13.8–46.2%, respectively. ConclusionsOur findings revealed that anaerobes susceptibility patterns have become less predictable due to an increase of resistance and suggest that periodic resistance surveillance should also be carried out for anaerobes in order to guide empirical therapy.

The gut microbiota modulates responses to anti-PD-1 and chemotherapy combination therapy and related adverse events in patients with advanced solid tumors.

Immune checkpoint inhibitors (ICIs) targeting programmed cell death protein 1 (PD-1) have been widely used in treating different malignancies. Several studies have reported that the gut microbiota modulates the response and adverse events (AEs) to ICIs in melanoma, non-small cell lung cancer (NSCLC), renal cell cancer and hepatocellular carcinoma, but data on other cancer types and ICI combination therapy are limited. Stool samples were collected from patients with cancer who received anti-PD-1 and chemotherapy combination treatment and were analyzed by fecal metagenomic sequencing. The microbiota diversity and composition were compared between the responder (R) and non-responder (NR) groups and the AE vs. the non-AE (NAE) groups. In addition, associated functional genes and metabolic pathways were identified. At baseline, the microbiota diversity of the groups was similar, but the genera Parabacteroides, Clostridia bacterium UC5.1_2F7, and Bifidobacterium dentium were enriched in the R group, whereas Bacteroides dorei and 11 species of Nocardia were enriched in the NR group. At 6 weeks, the beta diversity was significantly different between the R and NR groups. Further analysis found that 35 genera, such as Alipes, Parabacteroides, Phascolarctobacterium, Collinsella, Ruminiclostridium, Porphyromonas, and Butyricimonas and several genera of the Fibrobacteraceae family, were frequently distributed in the R group, whereas 17 genera, including Enterococcus, Lachnoclostridium, Hungatella, and Bilophila and several genera of the Pseudonocardiaceae and Beijerinckiaceae families, were more abundant in the NR group. A total of 66 and 52 Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologs (KOs) were significantly enriched in the R and NR groups, respectively. In addition, pathway analysis revealed functional differences in the gut microbacteria in the R group, including the enrichment of anabolic pathways and DNA damage repair (DDR) pathways. Dynamic comparisons of the bacterial composition at baseline, 6 weeks, and 12 weeks showed that the abundance of Weissella significantly increased in the R group at 6 weeks and the abundance of Fusobacterium and Anaerotruncus significantly increased in the NR group at 12 weeks. Linear discriminant analysis effect size analysis indicated that bacteria of Bacteroidetes, especially Bacteroides, were enriched in the NAE group, whereas flora of Firmcutes, such as Faecalibacterium prausnitzii, Bacteroides fragilis, and Ruminococcus lactaris, were enriched in the AE group. Beta diversity and differences in the gut microbiota modulated AEs and the response to anti-PD-1 blockade combined with chemotherapy, by regulating related anabolic and DDR pathways. Dynamic changes in the intestinal microbiome may predict the efficacy of PD-1 inhibitor-basedtherapy.

A Chinese medical nutrition therapy diet accompanied by intermittent energy restriction alleviates type 2 diabetes by enhancing pancreatic islet function and regulating gut microbiota composition

Medicine food homologous (MFH) plants and wholegrains have gained increasing attention for prevention and treatment of type 2 diabetes (T2D). Substantial evidence supports the effectiveness of intermittent energy restriction (IER) in T2D management. However, there are few studies that report intermittent use of a low-calorie pre-prepared food including MFH plants and wholegrains in T2D. The aim of this study was to investigate the effects of Chinese Medical Nutrition Therapy (CMNT), a MFH plants and wholegrains diet accompanied by IER, on glycemic control and potential mechanism. Ten-week-old diabetic db/db mice were randomly divided into CMNT group (feeding low-calorie mouse CMNT diet in day 1–4 and ad libitum regular chow for up to 7 days per cycle) and control group (ad libitum access to regular chow). The results showed that CMNT reduced fasting blood glucose, improved glucose tolerance with higher insulin secretion, attenuated macrophage infiltration, promoted β-cell proliferation of pancreatic islets, and increased diabetes-improving microbiota (Bacteroides, Rikenellaceae_RC9_gut_group and Coprococcus_1) in db/db mice. Additionally, we performed a pilot study evaluating CMNT in thirty-nine T2D patients without obesity. Participants with T2D randomly assigned to two groups: CMNT group (receiving a consecutive 5-day low-calorie human CMNT diet with 10 days of habitual eating per cycle for 90 days) and control group (continuing on a normal diet). We observed an improvement in glycemic control in CMNT group with significant reduction in HbA1c, fasting glucose, 2 h postprandial blood glucose but control group were not affected. After CMNT intervention, the abundance of the phylum Bacteroidetes, and genus Bacteroides, Parabacteroides and Roseburia were significantly higher than baseline in T2D patient, which were closely associated with glycemic control. These findings suggested that CMNT is a promising nutritional intervention approach in diabetes management.

Influences of Gastrointestinal Microbiota Dysbiosis on Serum Proinflammatory Markers in Epithelial Ovarian Cancer Development and Progression.

Simple SummaryAdvanced epithelial ovarian cancer (EOC) is the deadliest gynecologic cancer due to the lack of available early screening methods that are available in clinical settings. Unique gastrointestinal (GI) microbiota have been detected in the ovaries and peritoneal fluid of women with EOC that are not found in women without disease. However, there are limited data available to determine possible links in GI microbiota composition and early ovarian cancer development while women are largely asymptomatic. This research utilizes an EOC animal model to investigate the effects of GI microbial disruption on systemic inflammation during early disease development and progression. The identification of distinct GI microbial communities that may potentially mediate systemic immune response during carcinogenesis can open new opportunities to disentangle the complex ovarian tumor microenvironment for the discovery of valid clinical tools for early EOC detection.GI microbiota has been implicated in producing the inflammatory tumor microenvironment of several cancers. Women with ovarian cancer often report GI-related symptoms at diagnosis although minimal is known about the possible GI bacteria that may trigger pro-tumorigenic immune responses in early EOC. The purpose of this study was to investigate the influences of GI microbiota dysbiosis on serum inflammatory markers during EOC utilizing a rodent model. This experimental design consisted of C57BL/6 mice randomly assigned to either the microbiota dysbiosis group (n = 6) or control group (n = 5). The CD7BL/6 mice assigned to the microbiota dysbiosis group were administered a mixture of broad-spectrum antibiotics (bacitracin and neomycin) for 2 weeks. Both groups were injected intraperitoneally with mouse ovarian epithelial cells that induce ovarian tumorigenesis. Levels of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) were assessed in the serum, and the composition of the GI microbiota in fecal samples was measured using 16S rRNA gene sequencing. Overall CRP serum levels were significantly lower and TNFα levels were significantly higher in the microbiota dysbiosis group compared to the control group. The abundances of microbiota that correlated with CRP serum levels in the combined groups were genus Parabacteroides, Roseburia, and Emergencia and species Ruminococcus faecis, Parabacteroides distasonis, Roseburia Faecis, and Emergencia timonensis. This study provides evidence to support for further investigation of the GI microbial profiles in patients at risk of EOC.

The Genus Parabacteroides Is a Potential Contributor to the Beneficial Effects of Truncal Vagotomy–Related Bariatric Surgery

PurposeEvidences about the gut microbiota role in weight loss after bariatric surgery (BS) are growing. The objective of this study was to observe the changes of gut microbiota after sleeve gastrectomy (SG) and SG plus truncal vagotomy (SG-TV) and identify specific microbes that may contribute to the improvement of obesity after surgeries.Materials and MethodsForty high-fat diet-induced obesity (DIO) mice were randomized to SG, SG-TV, or sham operation (SH) groups. Body weight (BW) and fast blood glucose (FBG) were measured before and 1, 2, 4, 8, and 12 weeks post-operatively. Fecal samples were collected before and at post-operative week 12 and profiled using 16S rRNA relative and absolute quantitative sequencing.ResultsAfter the surgery, the SG and SG-TV surgeries significantly reduce BW and FBG levels compared with SH, and the SG-TV achieved better effects than SG. A decreasing trend in alpha diversity of gut microbiota and significant changes in taxonomic composition were observed after surgeries. Then, we identified a set of microbes and pathways significantly different in abundance after BS. The genus Parabacteroides and one pathway (polyketide sugar unit biosynthesis) increased in SG-TV group specially, which was also negatively correlated with BW and FBG.ConclusionSG and SG-TV indeed achieve effects of weight loss, but TV could enhance the efficacy of SG. The identified different microbes and pathways, like Parabacteroides, polyketide sugar unit biosynthesis, may partly mediate the beneficial effects of BS, and thus possibly contribute to the development of novel bacteria-based therapeutic approaches.Graphical

Parabacteroides pekinense sp. nov.: a new bacterium isolated from the stool of a healthy man living in China

Strain Quantibio-BCGUT is a new species from the genus Parabacteroides that was isolated from a stool sample of a 49-year-old healthy Chinese male adult. Cells are Gram-negative and obligate anerobic bacilli. Strain Quantibio-BCGUT exhibits 95.86% 16S rRNA gene sequence similarity to Parabacteroides merdae strain JCM 9497 (NR_041343.1), the phylogenetically closely related species with standing in nomenclature. Major fatty acids are C16:0, C18:0 and C19:0-IS. Quantibio-BCGUT exhibits a high level of resistance to aztreonam. Growth occurred at pH 5.5–9.0. Optimal growth was observed at 35 °C in YCFA medium in anerobic condition, no growth occurs at 25 °C or 50 °C. Strain grows in YCFA medium in the presence of 0.1%–2.0% (w/v) NaCl (optimum 1.0%). Based on the phenotypic and phylogenetic evidence, OrthoANI values and results of the biochemical tests, the new species is named Parabacteroides pekinense sp. nov., for which strain Quantibio-BCGU T (= CGMCC = QHBCGU) is proposed as the type strain.

THE SYNTHETIC GLYCAN KB295 OPTIMIZES MICROBIOME COMPOSITION AND FUNCTION IN ULCERATIVE COLITIS – RESULTS FROM A PROOF OF PRINCIPLE HUMAN STUDY

Abstract The pathogenesis of ulcerative colitis (UC) involves genetic susceptibility, immune-mediated tissue injury and environmental factors including disturbances of the gut microbiota. Nearly all current approved therapies modify host immunity, rather than directly targeting the microbiota. Fecal microbiota transplantation provides encouraging evidence for the therapeutic potential of gut microbiome modulation. Bacteria in the GI tract are ecologically differentiated by their ability to use specific glycans as growth substrates, making glycans a promising and safe alternative to target the microbiome. To explore this, we used an ex vivo fecal microbiota culture system to identify a synthetic glycan (KB295) with desirable microbiological activity and conducted a proof of principle study of safety and tolerability of KB295 in patients with UC. Fecal microbial communities from healthy subjects were incubated anaerobically with and without (negative control) KB295. KB295 increased short chain fatty acid (SCFA) production across ten fecal samples to a median concentration of 47.0 mM compared to 15.2 mM with the negative control in culture supernatants, including increases in acetate, propionate, and butyrate in all cases. Metagenomic sequencing of the ex vivo fecal pellets revealed that KB295 depleted pathobionts in the family Enterobacteriaceae to a median relative abundance of 10.8% compared to 38.2% with the negative control. Pathobiont depletion was associated with enrichments of diverse genera in the phyla Bacteroidetes and Firmicutes. Twelve patients with mild to moderate UC were enrolled in an open-label single-arm study with an 8-week intake of KB295. KB295 was well tolerated with generally mild adverse events, and only one AE resulted in discontinuation. The most frequently occurring adverse events were changes in bowel habit, flatulence, and headache. Fecal calprotectin and lactoferrin decreased by median values of 69.0% (n=11) and 86.0% (n=6), respectively, from screening to the end of the KB295 intake. Consistent with the ex vivo preclinical findings, of the subjects for whom we have data to date, the relative abundance of the fecal pathobiont family Enterobacteriaceae decreased from five participants, and the commensal genus Parabacteroides was enriched in four of five participants. These results establish a proof of principle for the glycobiological modulation of gut microbiome composition and function and provide insight into the potential utility of this strategy in patients with ulcerative colitis. The safety, tolerability, and encouraging evidence for reduced inflammation with KB295 call for a Phase 2 study, which is planned.

P098 Mucosal Microbiota Composition Predicts Infliximab Response in Inflammatory Bowel Diseases

Abstract Background The inflammatory bowel disease (iBD) etiology remain elusive and both genetic and environmental factors have been implicated in the establishment of systemic inflammatory reactions that typify IBD. A basic, modifiable environmental factor is the gut microbiota and dysbiosis seems to be a key factor in IBD pathogenesis. Nowadays, it is well known that anti-TNF therapy significantly improves the rates of remission in patients with inflammatory bowel disease (IBD), however, there is a subgroup of patients who do not respond to treatment. The aim of the present study is to profile changes in the mucosal gut microbiome before and after anti-TNF therapy and investigate its possibility to predict patient response at baseline. Methods Mucosal biopsy samples from IBD patients [14 Crohn’s disease patients (CD), 6 ulcerative colitis (UC) patients] and healthy controls (HC) were examined for differences in microbiota composition (16S rRNA gene sequencing) at baseline and upon completion of anti-TNF treatment, accordingly, via an in silico pipeline. Results Although no statistically significant differences at phylum level were noted, a relative reduction in Bacteroidetes and an increase in Actinobacteria, Fusobacteria and Chloroflexi were detected in IBD versus HC biopsies, however the microbiomes of UC, CD and HC display qualitative differences at the OTU level. At genus level, statistically significant differential abundance between the HC and IBD groups was observed. The genera Parabacteroides, Barnesiella, Butyricimonas, Ruminococcus_1, Ruminococcaceae_UCG013, Phascolarctobacterium, Ruminoclostridium_6, Paraprevotella as well as members of the Eubacterium_ruminantium group appear reduced in IBD, whereas Dialister abundance is increased. The genus Collinsella exhibits an induction during UC versus both HC and CD. Regarding anti-TNF treatment on the microbiome, Alpha-diversity is reduced after anti-TNF treatment. Beta-diversity indicates differences before and after treatment as well as between responders and non-responders. By using the biomarker discovery tool LEfSe, we identified microbial genera associated mainly with anti-TNF responders. Conclusion In the present study, we showed that the response to anti-TNF therapy is related to specific microbiota profiles in the gut mucosa. Correlation analysis between these parameters of response at baseline showed that the assessment of microbial taxa can further distinguish responders from non-responders.

P493 The synthetic glycan KB295 optimises microbiome composition and function in ulcerative colitis: Results from a proof of principle human study

Abstract Background Ulcerative colitis (UC) pathogenesis involves genetic susceptibility, immune-mediated tissue injury, and gut microbiota disturbances. Most approved therapies modify host immunity, rather than directly targeting the microbiota. Faecal microbiota transplantation provides encouraging evidence for the therapeutic potential of gut microbiome modulation. Gastrointestinal tract bacteria are ecologically differentiated by their ability to use specific glycans as growth substrates, making glycans a promising and safe alternative to target the microbiome. To explore this, we used an ex vivo faecal microbiota culture system to identify a synthetic glycan (KB295) with desirable microbiological activity and conducted a proof of principle study (NCT04508413) of safety and tolerability of KB295 in patients with UC. Methods In ex vivo studies, faecal microbial communities from healthy subjects were incubated anaerobically (negative control) ± KB295. Taxa counts from shotgun metagenomic sequencing data were used to evaluate microbial response to KB295. Short-chain fatty acid (SCFA) levels were also assessed. KB295 was evaluated in an open-label single-arm study in adult patients with mild to moderate UC. KB295 was ingested over an 8-wk period. Objectives included KB295 safety (primary) and effect on gut microbiota composition and faecal biomarkers. Results In ex vivo studies, KB295 increased SCFA levels across 10 faecal samples to a median of 47.0 vs 15.2 mM with negative control, including increases in acetate, propionate, and butyrate levels. Metagenomic sequencing showed pathobiont depletion in the family Enterobacteriaceae with KB295 to a median relative abundance of 10.8% vs 38.2% with negative control. Pathobiont depletion was associated with enrichments of diverse genera in the phyla Bacteroidetes and Firmicutes. In patients with UC (n=12), KB295 was well tolerated with generally mild adverse events (AEs). The most frequently occurring AEs were bowel habit changes, flatulence, and headache. Median faecal calprotectin and lactoferrin levels decreased by 69.0% (n=11) and 86.0% (n=6), respectively, from screening to end of the KB295 intake. Consistent with our ex vivo results, of the patients for whom we have data to date, the relative abundance of the faecal pathobiont family Enterobacteriaceae decreased in 5 of 5 participants, and the commensal genus Parabacteroides was enriched in 4 of 5 participants. Conclusion Our results establish a proof of principle for the glycan modulation of gut microbiome composition and function and provide insight into the potential utility of this strategy in patients with UC. The safety and tolerability of KB295, along with evidence of reduced inflammation, support a phase 2 study, which is planned.

Resistance and Endurance Exercise Training Induce Differential Changes in Gut Microbiota Composition in Murine Models.

Background: The effect of resistance training on gut microbiota composition has not been explored, despite the evidence about endurance exercise. The aim of this study was to compare the effect of resistance and endurance training on gut microbiota composition in mice.Methods: Cecal samples were collected from 26 C57BL/6N mice, divided into three groups: sedentary (CTL), endurance training on a treadmill (END), and resistance training on a vertical ladder (RES). After 2 weeks of adaption, mice were trained for 4 weeks, 5 days/week. Maximal endurance and resistance capacity test were performed before and after training. Genomic DNA was extracted and 16S Ribosomal RNA sequenced for metagenomics analysis. The percentages for each phylum, class, order, family, or genus/species were obtained using an open-source bioinformatics pipeline.Results: END showed higher diversity and evenness. Significant differences among groups in microbiota composition were only observed at genera and species level. END showed a significantly higher relative abundance of Desulfovibrio and Desulfovibrio sp., while Clostridium and C. cocleatum where higher for RES. Trained mice showed significantly lower relative abundance of Ruminococcus gnavus and higher of the genus Parabacteroides compared to CTL. We explored the relationship between relative taxa abundance and maximal endurance and resistance capacities after the training period. Lachnospiraceae and Lactobacillaceae families were negatively associated with endurance performance, while several taxa, including Prevotellaceae family, Prevotella genus, and Akkermansia muciniphila, were positively correlated. About resistance performance, Desulfovibrio sp. was negatively correlated, while Alistipes showed a positive correlation.Conclusion: Resistance and endurance training differentially modify gut microbiota composition in mice, under a high-controlled environment. Interestingly, taxa associated with anti- and proinflammatory responses presented the same pattern after both models of exercise. Furthermore, the abundance of several taxa was differently related to maximal endurance or resistance performance, most of them did not respond to training.

Parabacteroides distasonis induces depressive-like behavior in a mouse model of Crohn’s disease

Patients with inflammatory bowel disease (IBD) are particularly susceptible to behavioral diagnoses, and the microbiome has been repeatedly implicated in the pathogenesis of IBD. The intestinal microbiome’s ability to affect behavior has become increasingly recognized and studied. The so-called ‘psychobiome’ has been linked to a plethora of neurological and psychological diagnoses, including autism and Parkinson’s disease. Despite the ability of many bacterial species within the human intestinal microbiome to synthesize neurotransmitters, it has never been previously reported that a single bacterial species is sufficient to induce depression. Here, we demonstrate that our mouse model of Crohn’s disease (CD)-like ileitis, the SAMP1/YitFc (SAMP1), does not exhibit baseline behavioral abnormalities. By comparison, SAMP6 mice develop depressive-like behavior that is associated with a rise in the GABA-producing bacterial genus Parabacteroides. We finally demonstrate that administration of Parabacteroides distasonis into our SAMP1 mice induces depressive-like behavior. Colonization with P. distasonis was not associated with increased intestinal inflammation or alterations in other measures of behavior. The intestinal environment of CD may be particularly conducive to colonization with P. distasonis and subsequent induction of depressive-like behavior. To our knowledge, this is the first report of a bacterial species specifically inducing depressive-like behavior.

Gut microbial taxa elevated by dietary sugar disrupt memory function

Emerging evidence highlights a critical relationship between gut microbiota and neurocognitive development. Excessive consumption of sugar and other unhealthy dietary factors during early life developmental periods yields changes in the gut microbiome as well as neurocognitive impairments. However, it is unclear whether these two outcomes are functionally connected. Here we explore whether excessive early life consumption of added sugars negatively impacts memory function via the gut microbiome. Rats were given free access to a sugar-sweetened beverage (SSB) during the adolescent stage of development. Memory function and anxiety-like behavior were assessed during adulthood and gut bacterial and brain transcriptome analyses were conducted. Taxa-specific microbial enrichment experiments examined the functional relationship between sugar-induced microbiome changes and neurocognitive and brain transcriptome outcomes. Chronic early life sugar consumption impaired adult hippocampal-dependent memory function without affecting body weight or anxiety-like behavior. Adolescent SSB consumption during adolescence also altered the gut microbiome, including elevated abundance of two species in the genus Parabacteroides (P. distasonis and P. johnsonii) that were negatively correlated with hippocampal function. Transferred enrichment of these specific bacterial taxa in adolescent rats impaired hippocampal-dependent memory during adulthood. Hippocampus transcriptome analyses revealed that early life sugar consumption altered gene expression in intracellular kinase and synaptic neurotransmitter signaling pathways, whereas Parabacteroides microbial enrichment altered gene expression in pathways associated with metabolic function, neurodegenerative disease, and dopaminergic signaling. Collectively these results identify a role for microbiota “dysbiosis” in mediating the detrimental effects of early life unhealthy dietary factors on hippocampal-dependent memory function.

Active DNRA and denitrification in oxic hypereutrophic waters

Since the start of synthetic fertilizer production more than a hundred years ago, the coastal ocean has been exposed to increasing nutrient loading, which has led to eutrophication and extensive algal blooms. Such hypereutrophic waters might harbor anaerobic nitrogen (N) cycling processes due to low-oxygen microniches associated with abundant organic particles, but studies on nitrate reduction in coastal pelagic environments are scarce. Here, we report on 15N isotope-labeling experiments, metagenome, and RT-qPCR data from a large hypereutrophic lagoon indicating that dissimilatory nitrate reduction to ammonium (DNRA) and denitrification were active processes, even though the bulk water was fully oxygenated (> 224 µM O2). DNRA in the bottom water corresponded to 83% of whole-ecosystem DNRA (water + sediment), while denitrification was predominant in the sediment. Microbial taxa important for DNRA according to the metagenomic data were dominated by Bacteroidetes (genus Parabacteroides) and Proteobacteria (genus Wolinella), while denitrification was mainly associated with proteobacterial genera Pseudomonas, Achromobacter, and Brucella. The metagenomic and microscopy data suggest that these anaerobic processes were likely occurring in low-oxygen microniches related to extensive growth of filamentous cyanobacteria, including diazotrophic Dolichospermum and non-diazotrophic Planktothrix. By summing the total nitrate fluxes through DNRA and denitrification, it results that DNRA retains approximately one fifth (19%) of the fixed N that goes through the nitrate pool. This is noteworthy as DNRA represents thus a very important recycling mechanism for fixed N, which sustains algal proliferation and leads to further enhancement of eutrophication in these endangered ecosystems.

Distinctive Microbial Signatures and Gut-Brain Crosstalk in Pediatric Patients with Coeliac Disease and Type 1 Diabetes Mellitus

Coeliac disease (CD) and Type 1 diabetes mellitus (T1DM) are immune-mediated diseases. Emerging evidence suggests that dysbiosis in the gut microbiome plays a role in the pathogenesis of both diseases and may also be associated with the development of neuropathy. The primary goal in this cross-sectional pilot study was to identify whether there are distinct gut microbiota alterations in children with CD (n = 19), T1DM (n = 18) and both CD and T1DM (n = 9) compared to healthy controls (n = 12). Our second goal was to explore the relationship between neuropathy (corneal nerve fiber damage) and the gut microbiome composition. Microbiota composition was determined by 16S rRNA gene sequencing. Corneal confocal microscopy was used to determine nerve fiber damage. There was a significant difference in the overall microbial diversity between the four groups with healthy controls having a greater microbial diversity as compared to the patients. The abundance of pathogenic proteobacteria Shigella and E. coli were significantly higher in CD patients. Differential abundance analysis showed that several bacterial amplicon sequence variants (ASVs) distinguished CD from T1DM. The tissue transglutaminase antibody correlated significantly with a decrease in gut microbial diversity. Furthermore, the Bacteroidetes phylum, specifically the genus Parabacteroides was significantly correlated with corneal nerve fiber loss in the subjects with neuropathic damage belonging to the diseased groups. We conclude that disease-specific gut microbial features traceable down to the ASV level distinguish children with CD from T1DM and specific gut microbial signatures may be associated with small fiber neuropathy. Further research on the mechanisms linking altered microbial diversity with neuropathy are warranted.

Intratracheally instillated diesel PM2.5 significantly altered the structure and composition of indigenous murine gut microbiota

A diverse and large community of gut microbiota reside in the intestinal tract of various organisms and play important roles in metabolism and immune homeostasis of its host. The disorders of microbiota-host interaction have been closely associated with numerous chronic inflammatory and metabolic diseases, including inflammatory bowel disease and type 2 diabetes. The accumulating evidence has shown that fine particulate matter (PM2.5) exposure contributes to the diabetes, atherosclerosis and inflammatory bowel diseases; however, few studies have explored the impact of inhaled diesel PM2.5 on gut microbiota in vivo. In this study, C57BL/6J mice were exposed to diesel PM2.5 for 14 days via intratracheal instillation, and colon tissues and feces were harvested for microbiota analysis. Using high-throughput sequencing technology, we observed that intratracheally instillated diesel PM2.5 significantly altered the gut microbiota diversity and community. At the phylum and genus levels, principal coordinate analysis (PCoA) and principal component analysis (PCA) indicated pronounced segregation of microbiota compositions, which were further confirmed by β diversity analysis. As the most affected phylum, Bacteroidetes was greatly diminished by diesel PM2.5. On the genus level, Escherichia, Parabacteroides, Akkermansia, and Oscillibacter were significantly elevated by diesel PM2.5 exposure. Our findings provided clear evidence that exposure to diesel PM2.5 via intratracheal instillation deteriorated the gastrointestinal (GI) tract and significantly altered the structure and composition of gut microbiota, which might subsequently contribute to the developmental abnormalities of inflammation, immunity and metabolism.