Changes In Bacterial Composition Research Articles

Metal-organic-framework-based sitagliptin-release platform for multieffective radiation-induced intestinal injury targeting therapy and intestinal flora protective capabilities

In patients with abdominal or pelvic tumors, radiotherapy can result in radiation-induced intestinal injury (RIII), a potentially severe complication for which there are few effective therapeutic options. Sitagliptin (SI) is an oral hypoglycemic drug that exhibits antiapoptotic, antioxidant, and anti-inflammatory activity, but how it influences RIII-associated outcomes has yet to be established. In this study, a pH-responsive metal-organic framework-based nanoparticle platform was developed for the delivery of SI (SI@ZIF-8@MS NP). These NPs incorporated mPEG-b-PLLA (MS) as an agent capable of resisting the effects of gastric acid, and are capable of releasing Zn2+ ions. MS was able to effectively shield these SI@ZIF-8 NPs from rapid degradation when exposed to an acidic environment, enabling the subsequent release of SI and Zn2+ within the intestinal fluid. Notably, SI@ZIF-8@MS treatment was able to mitigate radiation-induced intestinal dysbiosis in these mice. restored radiation-induced changes in bacterial composition. In summary, these data demonstrate the ability of SI@ZIF-8@MS to protect against WAI-induced intestinal damage in mice, suggesting that these NPs represent a multimodal targeted therapy that can effectively be used in the prevention or treatment of RIII.

Characteristics of the intestinal tract microbiota in calves with various forms of acute catarrhal bronchopneumonia

The intestinal barrier is one of the most important components that maintain gastrointestinal homeostasis, therefore changes in bacterial composition can lead to increased intestinal permeability and the development of intestinal translocation of opportunistic microorganisms, with the subsequent development or complication of various infectious diseases. A comparative description of the microbiota of the intestinal tract of calves with compensated, subcompensated and decompensated acute catarrhal bronchopneumonia of calves was carried out in the conditions of livestock farms of Vladimir and Moscow Oblasts. Calves aged 1–3 months with acute catarrhal bronchopneumonia (n = 37) were used for the study. The severity of the disease was assessed based on clinical and laboratory tests. The samples taken from clinically healthy animals (n = 8) were used as controls. It has been shown that in calves with compensated acute catarrhal bronchopneumonia, the qualitative and quantitative composition of the intestinal microbiome does not differ from clinically healthy animals. During the clinical manifestation of subcompensated and decompensated acute catarrhal bronchopneumonia in calves, a significant quantitative and qualitative shift in the microbiome occurs in the intestines, which indicates the occurrence of dysbiosis. We believe that this area is quite relevant and requires further scrupulous research.

Use of a peracetic acid (PAA) disinfectant to reduce total viable bacteria count in hospital wastewater drains

The periphery of the hospital water system interfaces at multiple points with patients and staff in clinical areas. This comprises mostly sinks and showers and presents a significant infection control risk. Wastewater drains in particular act as a reservoir of pathogens that can be transmitted to patients. Numerous strategies have been investigated as potential methods to reduce biofilm and bacterial load including regular application of biocidal chemicals. Traditional methods of assessing the efficacy of such products relies on culture-based microbiological techniques, usually targeting a limited range of key pathogens. We assessed the efficacy of a peracetic acid containing drain disinfectant product on seven clinical handwash basin drains, taking daily samples over six weeks (before, during and after use of the drain disinfectant product). We used a rapid, culture-independent estimation of total bacterial viable count (TVC) to assess efficacy. We applied long-read metagenomic sequencing to study the entire drain microbiome, which allowed taxonomic changes to be documented following use of the drain disinfectant product. All samples were found to be heavily contaminated, however the drain disinfectant product reduced the TVC from an estimated mean of 4228cfu/mL to 2874cfu/mL. This reduction was sustained in the two weeks following cessation of the product. Long-read metagenomic sequencing showed a microbiome dominated with Gram-negative organisms, with some taxonomic shifts in samples before and after application of the drain disinfectant. The impact on hospital-acquired infections from reducing bioburden in hospital drains by approximately a third, along with any associated changes in bacterial composition, needs evaluation in future studies.

Microbial Composition and Quality Changes in Whole Golden Pomfret (Trachinotus ovatus) During Refrigerated, Ice, and Vacuum-Packed Storage

ABSTRACT This study evaluated the quality and bacterial composition changes in whole golden pomfret under refrigeration, ice storage, and vacuum packaging at 4°C . Ice storage and vacuum packaging delayed sensory quality deterioration, limited spoilage bacteria proliferation, and slowed biogenic amines formation, total volatile base nitrogen accumlation, and ATP-related compounds degradation. In addition, Bacillus dominated fresh golden pomfret. Psychrobacter, Shewanella, and Acinetobacter were predominant in control and ice storage groups, while Shewanella and Aeromonas prevailed in the vacuum packaging group after storage. In conclusion, the best storage condition for whole golden pomfret fish is ice storage.

Longitudinal analysis of the skin microbiome in association with hand eczema, hand hygiene practices and moisturizer use.

The skin microbiota maintains a physical and immunological barrier to the environment. Little is known about how the microbiome changes over time or the effect of hand hygiene practices and moisturizer use. To assess sex-specific changes in skin bacteria over time, and how the microbiome is related to self-reported hand eczema, hand hygiene practices and use of moisturizers. Swab samples from the dorsal hand were collected at baseline and 6.5 years later during the COVID-19 pandemic, in 168 participants from the RHINESSA study in Bergen, Norway. The skin samples were analysed by 16S rRNA amplicon sequencing. The alpha diversity of the hand microbiome increased from baseline to follow-up, and beta diversity differed by sex at both time points. The relative abundance increased for several bacteria from baseline to follow-up, with sex-specific differences. Current hand eczema and aggravating hand eczema during the COVID-19 pandemic were associated with an increase in Staphylococcus. High hand washing frequency at home was associated with lower alpha diversity and with higher abundance of Staphylococcus, Corynebacterium, Finegoldia, and Pseudomonas and lower abundance of Propionibacterium and Pelomonas. The alpha diversity increased with increasing time passing between hand washing and sampling, whereas more frequent moisturizer use was associated with significantly lower alpha diversity, and a change in abundance for some bacteria, such as more Pseudomonas. This longitudinal study revealed an overall increase in skin microbial diversity over a 6-year period, which was unexpected since follow-up was performed during the COVID-19 pandemic when vigorous hand hygienic practices were introduced. Sex-specific differences were identified at both time points. Individuals with hand eczema seem to develop a more dysbiotic skin bacterial community over time. Hand washing and use of moisturizers, with typically gender-specific habitual patterns, may lead to change in bacterial composition.

P030 Gut-host metabolites and microbiota interactions in a murine model of checkpoint inhibitor induced colitis

Abstract Background The advent of Immune Checkpoint Inhibitors (CPIs) has revolutionised cancer treatment by bolstering anti-tumour immune responses. However, the clinical success of CPIs is hampered by immune-related adverse events (irAEs), with colitis posing a common and formidable challenge. Despite this, the precise mechanisms triggering CPI-induced colitis remain elusive. Recognising the influence of gut microbiota on CPI therapy response and colitis development, this study seeks to unravel the intricate details of these mechanisms to facilitate the development of targeted therapies. Methods Utilising a murine model of CPI-induced colitis, we combined CPI therapy with faecal microbial transplant (FMT) of colitogenic bacteria. FMT induced colitogenic bacteria in wild-type mice, followed by weekly injections of anti-CTLA4 and anti-PD1 for 3 weeks. Metataxonomic data, obtained through 16S rRNA gene amplicon sequencing, and metabolomic profiles, captured by 1H-NMR spectroscopy, were analysed. Alpha and beta diversity, as well as differential expression of taxa, were assessed using 16S data. Metabolomics data underwent multivariate and univariate analyses to identify metabolic profiles and differential metabolites. Pathway analysis was conducted with MetaboAnalyst. Correlation analyses were performed between bacterial taxa at the family level and metabolite concentrations. Results After one week of FMT and CPI treatment, distinct profiles in faecal metabolome and microbiome were observed through Principal Component Analysis (PCA) and Principal Coordinates Analysis (PCoA) for beta-diversity, respectively. Altered metabolites included increased trimethylamine, methylamine, pyruvate, and cytidine, along with reduced tryptophan and proline. Changes in bacterial composition were noted, with increased Bacteroides, Faecalibaculum, Mucispirillum, and Roseburia, and decreased Muribaculum. Metabolic differences persisted after 3 weeks of treatment, revealing additionally decreased acetate, propionate and tyramine. Pathway analysis highlighted profound alterations in tyrosine, alanine, aspartate and glutamate metabolism, pyrimidine metabolism and glycolysis. Desulfovibrionaceae was positively correlated with dimethylamine, glycine and valine. Bacteroidaceae was positively correlated with propionate and butyrate. Conclusion This study provides novel mechanistic insights into the metabolite and microbiota-metabolism pathways associated with CPI-induced colitis. The alterations in short-chain fatty acids (SCFA), amino acids, and the SCFA-producing bacteria and colitogenic bacteria shed light on the metabolic changes underlying CPI colitis. Targeting these microbiomes and metabolites could offer promising avenues for enhancing clinical outcomes during CPI therapy.

Core microbiota for nutrient digestion remained and ammonia utilization increased after continuous batch culture of rumen microbiota in vitro.

This study aimed to investigate the digestive function, urea utilization ability, and bacterial composition changes in rumen microbiota under high urea (5% urea in diet) over 23 days of continuous batch culture in vitro. The gas production, dry matter digestibility, and bacterial counts were determined for the continuously batch-cultured rumen fluid (CRF). The changes in fermentation parameters, NH3-N utilization efficiency, and microbial taxa were analyzed in CRF and were compared with that of fresh rumen fluid (RF), frozen rumen fluid (FRF, frozen rumen fluid at -80°C for 1 month), and the mixed rumen fluid (MRF, 3/4 RF mixed with 1/4 CRF) with in vitro rumen fermentation. The results showed that the dry matter digestibility remained stable while both the microbial counts and diversity significantly decreased over the 23 days of continuous batch culture. However, the NH3-N utilization efficiency of the CRF group was significantly higher than that of RF, FRF, and MRF groups (p < 0.05), while five core genera including Succinivibrio, Prevotella, Streptococcus, F082, and Megasphaera were retained after 23 days of continuous batch culture. The NH3-N utilization efficiency was effectively improved after continuous batch culture in vitro, and Streptococcus, Succinivibrio, Clostridium_sensu_stricto_1, p.251.o5, Oxalobacter, Bacteroidales_UCG.001, and p.1088.a5_gut_group were identified to explain 75.72% of the variation in NH3-N utilization efficiency with the RandomForest model. Thus, core bacterial composition and function retained under high urea (5% urea in diet) over 23 days of continuous batch culture in vitro, and bacterial biomarkers for ammonia utilization were illustrated in this study. These findings might provide potential applications in improving the efficiency and safety of non-protein nitrogen utilization in ruminants.

Effects of supplementation of live and heat-treated Bifidobacterium animalis subspecies lactis CECT 8145 on glycemic and insulinemic response, fecal microbiota, systemic biomarkers of inflammation, and white blood cell gene expression of adult dogs.

The popularity of functional ingredients such as probiotics and postbiotics has increased as pet owners seek ways to improve the health quality and longevity of their pets. Limited research has been conducted regarding the use of probiotics and postbiotics and their effects on canine health. The objective of this study was to evaluate the effects of daily supplementation of Bifidobacterium animalis subsp. lactis CECT 8145, in both live probiotic (PRO) and heat-treated postbiotic (POST) forms, on fecal fermentative end-products and microbiome, insulin sensitivity, serum gut hormones, oxidative stress, inflammatory biomarkers, and white blood cell gene expression of adult dogs. Eighteen adult beagles and 18 adult English pointers were used in a double-blinded placebo-controlled parallel group design, with 12 animals per group (6 English pointers and 6 beagles). The study began with a 60 d adaptation period followed by a 90 d period of daily supplementation with either PRO, POST, or placebo (maltodextrin; CON). Longitudinal assessment of body weight, body condition score, and pelvic circumference did not differ among dietary supplements (P > 0.05). Throughout the experimental period, fecal scores did not differ (P > 0.05); however, fecal pH was lower (P = 0.0049) in the dogs fed POST compared with CON. A higher fecal concentration of propionate (P = 0.043) was observed in dogs fed PRO and POST when compared with CON. While PRO and POST supplementation were associated with changes in bacterial composition at the family and genus level, the overall richness and diversity of the microbiome were not significantly affected. Functional analysis of the metagenome also suggests that PRO and POST supplementation induced potentially beneficial changes in the abundance of pathways involved in pathogenicity, amino acid biosynthesis, and DNA repair. No differences in glycemic or insulinemic responses were observed among the groups (P > 0.05). Dogs supplemented with PRO had a higher (P < 0.05) mean white blood cell leptin relative fold gene expression compared with groups POST and CON. Serum metabolites and complete blood cell counts were within normal ranges and all dogs remained healthy throughout the study. Together, these data suggest that the PRO and POST can safely be supplemented for dogs. Moreover, the results of this study support further investigation of the role of PRO and POST in supporting parameters related to gut health and hormonal regulation.

Assessing the influence of diverse phosphorus sources on bacterial communities and the abundance of phosphorus cycle genes in acidic paddy soils.

The impact of chemical fertilizers on soil microbial communities is well acknowledged. This study assesses the influence of various phosphorus sources on soil bacterial composition, abundance, and Phosphorus Cycle Gene Abundance. Three phosphorus sources (natural phosphate rock, triple super phosphate (TSP), and chemical fertilizer NPK) were field tested following two rice cultivation cycles. Soil samples were subsequently collected and analyzed for bacterial groups and phosphorus cycle genes. Results indicated that the bacterial community composition remained consistent, comprising five main phyla: Firmicutes, Actinobacteria, Proteobacteria, Halobacterota, and Chloroflexia, regardless of fertilizer type. NPK fertilizer significantly reduced the relative abundance of Chloroflexia by 19% and Firmicutes by 16.4%, while increasing Actinobacteria and Proteobacteria by 27.5 and 58.8%, respectively. TSP fertilizer increased Actinobacteria by 27.1% and Halobacterota by 24.8%, but reduced Chloroflexia by 8.6%, Firmicutes by 12.6%, and Proteobacteria by 0.6%. Phosphate rock application resulted in reductions of Chloroflexia by 27.1%, Halobacterota by 22.9%, and Firmicutes by 6.2%, alongside increases in Actinobacteria by 46.6% and Proteobacteria by 23.8%. Combined application of TSP, NPK, and phosphate rock led to increases in Proteobacteria (24-40%) and Actinobacteria (13-39%), and decreases in Chloroflexia (5.2-22%) and Firmicutes (6-12.3%) compared to the control (T0). While the different phosphorus sources did not alter the composition of phosphorus cycle genes, they did modulate their abundance. NPK fertilizer did not significantly affect ppK genes (57-59%) but reduced gcd (100 to 69%), 3-phytase (74 to 34%), appA (91 to 63%), and phoD (83 to 67%). Phosphate rock reduced appA and gcd by 27 and 15%, respectively, while increasing 3-phytase by 19%. TSP decreased ppK and phoD by 42 and 40%, respectively, and gcd and appA by 34 and 56%, respectively. Combined fertilizers reduced appA (49 to 34%), 3-phytase (10 to 0%), and gcd (27 to 6%), while increasing ppK (72 to 100%). Among tested phosphorus sources, natural phosphate rock was best, causing moderate changes in bacterial composition and phosphorus genes, supporting balanced soil microbial activity. These findings highlight the complex interactions between fertilizers and soil microbial communities, underscoring the need for tailored fertilization strategies to maintain soil health and optimize agricultural productivity.

Non-significant influence between aerobic and anaerobic sample transport materials on gut (fecal) microbiota in healthy and fat-metabolic disorder Thai adults.

The appropriate sample handling for human fecal microbiota studies is essential to prevent changes in bacterial composition and quantities that could lead to misinterpretation of the data. This study firstly identified the potential effect of aerobic and anaerobic fecal sample collection and transport materials on microbiota and quantitative microbiota in healthy and fat-metabolic disorder Thai adults aged 23-43 years. We employed metagenomics followed by 16S rRNA gene sequencing and 16S rRNA gene qPCR, to analyze taxonomic composition, alpha diversity, beta diversity, bacterial quantification, Pearson's correlation with clinical factors for fat-metabolic disorder, and the microbial community and species potential metabolic functions. Our study successfully obtained microbiota results in percent and quantitative compositions. Each sample exhibited quality sequences with a >99% Good's coverage index, and a relatively plateau rarefaction curve. Alpha diversity indices showed no statistical difference in percent and quantitative microbiota OTU richness and evenness, between aerobic and anaerobic sample transport materials. Obligate and facultative anaerobic species were analyzed and no statistical difference was observed. Supportively, the beta diversity analysis by non-metric multidimensional scale (NMDS) constructed using various beta diversity coefficients showed resembling microbiota community structures between aerobic and anaerobic sample transport groups (P = 0.86). On the other hand, the beta diversity could distinguish microbiota community structures between healthy and fat-metabolic disorder groups (P = 0.02), along with Pearson's correlated clinical parameters (i.e., age, liver stiffness, GGT, BMI, and TC), the significantly associated bacterial species and their microbial metabolic functions. For example, genera such as Ruminococcus and Bifidobacterium in healthy human gut provide functions in metabolisms of cofactors and vitamins, biosynthesis of secondary metabolites against gut pathogens, energy metabolisms, digestive system, and carbohydrate metabolism. These microbial functional characteristics were also predicted as healthy individual biomarkers by LEfSe scores. In conclusion, this study demonstrated that aerobic sample collection and transport (<48 h) did not statistically affect the microbiota and quantitative microbiota analyses in alpha and beta diversity measurements. The study also showed that the short-term aerobic sample collection and transport still allowed fecal microbiota differentiation between healthy and fat-metabolic disorder subjects, similar to anaerobic sample collection and transport. The core microbiota were analyzed, and the findings were consistent. Moreover, the microbiota-related metabolic potentials and bacterial species biomarkers in healthy and fat-metabolic disorder were suggested with statistical bioinformatics (i.e., Bacteroides plebeius).

Changes in bacterial composition and metabolite profiles during kimchi fermentation with different garlic varieties

Garlic, a key ingredient in kimchi, is an indispensable source of lactic acid bacteria, which are essential for fermentation. This study explored the effects of various garlic varieties on kimchi fermentation, focusing on changes in microbial communities and metabolite profiles. We observed that the type of garlic used did not significantly alter the microbial community. However, the presence of garlic itself made a significant difference. Specifically, kimchi with garlic showed higher abundance of Leuconostoc and Weissella, which are bacteria primarily responsible for kimchi fermentation. Additionally, kimchi containing garlic had increased levels of mannitol and fructose, which significantly influence taste; however, lactic acid and putrescine levels were decreased. Therefore, the addition of garlic directly contributes to the flavor profile of kimchi. Sixty-two metabolites were identified using gas chromatography and mass spectrometry. The variety of garlic added influenced the metabolite profiles of kimchi, particularly in the later stages of fermentation. These profiles were categorized based on the garlic's origin, whether from southern or northern ecotypes (R2X = 0.933, R2Y = 0.986, Q2 = 0.878). These findings confirm that both the presence and the variety of garlic significantly impact the microbial ecology and metabolites during kimchi fermentation, underscoring its essential role in the process.

Gut microbiome composition: link between sports performance and protein absorption?

Sufficient protein intake is essential for adequate physical condition and athletic performance. However, numerous factors can influence the absorption of consumed protein, including timing, type of protein intake, and gut microbiota. In the present study, elite male water polo players consumed a plant-based, vegan protein supplement with (n = 10) or without (n = 10) pre- and probiotics daily during the 31-day study period. We determined the anthropometric characteristics and body composition, dietary habits, gut microbiota composition, and blood parameters of the players at the beginning and at the end of the study. Body composition parameters were analyzed using the InBody 970 bioimpedance analyzer. Gut microbiome composition was determined from stool samples by metagenome sequencing. Paired and unpaired t-tests were used to determine differences between body composition and blood parameters within the groups and between the two groups at the two different sampling times. The Wilcoxon test was used to determine the change in bacterial composition during the study. Correlations between changes in body composition, blood parameters, and taxonomic groups were analyzed using a linear correlation calculation. Skeletal muscle mass (p < 0.001), body cell mass (p = 0.002), arm circumference (p = 0.003), and protein mass (p < 0.001) increased, while body fat mass (p = 0.004) decreased significantly in the intervention group which consumed pre- and probiotics in addition to protein supplement. Activated acetate (reductive TCA cycle I) and propionate (pyruvate fermentation to propanoate I) pathways correlated positively with increased skeletal muscle mass (p < 0.01 and p < 0.05), and the relative abundance of butyrate-producing species showed a significant positive correlation with changes in body fat mass in the intervention group (p < 0.05). These correlations were not observed in the control group without the intake of pre- and probiotics. The composition of the gut microbiota may influence protein absorption and therefore body composition and consequently physical condition and sports performance.

Linking ecological niches to bacterial community structure and assembly in polluted urban aquatic ecosystems.

Bacterial communities play crucial roles in the functioning and resilience of aquatic ecosystems, and their responses to water pollution may be assessed from ecological niches. However, our understanding of such response patterns and the underlying ecological mechanisms remains limited. In this study, we comprehensively investigated the effects of water pollution on the bacterial structure and assembly within different ecological niches, including water, sediment, submerged plant leaf surfaces, and leaf surfaces, using a 16S high-throughput sequencing approach. Ecological niches had a greater impact on bacterial community diversity than pollution, with a distinct enrichment of unique dominant phyla in different niches. This disparity in diversity extends to the bacterial responses to water pollution, with a general reduction in α-diversity observed in the niches, excluding leaf surfaces. Additionally, the distinct changes in bacterial composition in response to pollution should be correlated with their predicted functions, given the enrichment of functions related to biogeochemical cycling in plant surface niches. Moreover, our study revealed diverse interaction patterns among bacterial communities in different niches, characterized by relatively simply associations in sediments and intricate or interconnected networks in water and plant surfaces. Furthermore, stochastic processes dominated bacterial community assembly in the water column, whereas selective screening of roots and pollution events increased the impact of deterministic processes. Overall, our study emphasizes the importance of ecological niches in shaping bacterial responses to water pollution. These findings improve our understanding of the complicated microbial response patterns to water pollution and have ecological implications for aquatic ecosystem health.

Gastric microbiota in patients with gastric MALT lymphoma according to Helicobacter pylori infection

Gastric Mucosa Associated Lymphoid Tissue lymphoma (GML) development is triggered by Helicobacter pylori (H. pylori) infection. Little is known about the impact of H. pylori infection on gastric microbiota. The gastric microbiota was retrospectively investigated using 16S rRNA gene sequencing in 32 patients with untreated GML (10 H. pylori-positive and 22 H. pylori-negative), 23 with remitted and 18 refractory GML and 35 controls. Differences in microbial diversity, bacterial composition and taxonomic repartition were assessed. There was no change in diversity and bacterial composition between GML and control patients taking into account H. pylori status. Differential taxa analysis identified specific changes associated with H. pylori-negative GML: the abundances of Actinobacillus, Lactobacillus and Chryseobacterium were increased while the abundances of Veillonella, Atopobium, Leptotrichia, Catonella, Filifactor and Escherichia_Shigella were increased in control patients. In patients with remitted GML, the genera Haemophilus and Moraxella were significantly more abundant than in refractory patients, while Atopobium and Actinomyces were significantly more abundant in refractory patients. Detailed analysis of the gastric microbiota revealed significant changes in the bacterial composition of the gastric mucosa in patients with GML that may have a role in gastric lymphomagenesis but not any new pathobionts.

Oral Microbiota: The Influences and Interactions of Saliva, IgA, and Dietary Factors in Health and Disease.

Recent advances in metagenomic analyses have made it easier to analyze microbiota. The microbiota, a symbiotic community of microorganisms including bacteria, archaea, fungi, and viruses within a specific environment in tissues such as the digestive tract and skin, has a complex relationship with the host. Recent studies have revealed that microbiota composition and balance particularly affect the health of the host and the onset of disease. Influences such as diet, food preferences, and sanitation play crucial roles in microbiota composition. The oral cavity is where the digestive tract directly communicates with the outside. Stable temperature and humidity provide optimal growth environments for many bacteria. However, the oral cavity is a unique environment that is susceptible to pH changes, salinity, food nutrients, and external pathogens. Recent studies have emphasized the importance of the oral microbiota, as changes in bacterial composition and balance could contribute to the development of systemic diseases. This review focuses on saliva, IgA, and fermented foods because they play critical roles in maintaining the oral bacterial environment by regulating its composition and balance. More attention should be paid to the oral microbiota and its regulatory factors in oral and systemic health.

New Preventive Strategy against Oral Biofilm Formation in Caries-Active Children: An In Vitro Study.

Quorum quenching (QQ) is the inhibition of bacterial communication, i.e., quorum sensing (QS). QS is a key mechanism in regulating biofilm formation and phenotype in complex bacterial communities, such as those found within cariogenic biofilms. Whereas QQ approaches were shown to effectively reduce biomass, knowledge of their impact on the taxonomic composition of oral polymicrobial biofilms remains scarce. Here, we investigate the effect of the QQ lactonase Aii20J on biomass production and taxonomical composition of biofilms. We collected supragingival plaque samples from 10 caries-free and 10 caries-active children and cultured them to generate in vitro biofilms. We describe significant biomass reductions upon Aii20J exposure, as assessed by crystal violet assays. Taxonomical profiling using 16S rRNA gene amplicon sequencing revealed no significant changes in bacterial composition at the genus level. Interestingly, at the species level Aii20J-treatment increased the abundance of Streptococcus cristatus and Streptococcus salivarius. Both S. cristatus and S. salivarius express pH-buffering enzymes (arginine deiminase and urease, respectively) that catalyze ammonia production, thereby potentially raising local pH and counteracting the biofilm's cariogenic potential. Within the limitations of the study, our findings provide evidence of the biofilm-modulating ability of QQ and offer novel insights into alternative strategies to restore homeostasis within dysbiotic ecosystems.

Gut instinct: Sex differences in the gut microbiome are associated with changes in adolescent nociception following maternal separation in rats.

Adolescent chronic pain is a growing public health epidemic. Our understanding of its etiology is limited; however, several factors can increase susceptibility, often developing in response to an acute pain trigger such as a surgical procedure or mild traumatic brain injury (mTBI), or an adverse childhood experience (ACE). Additionally, the prevalence and manifestation of chronic pain is sexually dimorphic, with double the rates in females than males. Despite this, the majority of pre-clinical pain research focuses on males, leaving a gap in mechanistic understanding for females. Given that emerging evidence has linked the gut microbiome and the brain-gut-immune axis to various pain disorders, we aimed to investigate sex-dependent changes in taxonomic and functional gut microbiome features following an ACE and acute injury as chronic pain triggers. Male and female Sprague Dawley rat pups were randomly assigned to either a maternal separation (MS) or no stress paradigm, then further into a sham, mTBI, or surgery condition. Chronically, the von Frey test was used to measure mechanical nociception, and fecal samples were collected for 16S rRNA sequencing. Animals in the surgery group had an increase in pain sensitivity when compared to mTBI and sham groups, and this was complemented by changes to the gut microbiome. In addition, significant sex differences were identified in gut microbiome composition, which were exacerbated in response to MS. Overall, we provide preliminary evidence for sex differences and ACE-induced changes in bacterial composition that, when combined, may be contributing to heterogeneity in pain outcomes.

Investigating the modulatory effects of Moringa oleifera on the gut microbiota of chicken model through metagenomic approach.

This study aimed to assess the effects of supplementing chicken feed with Moringa oleifera leaf powder, a phytobiotic, on the gastrointestinal microbiota. The objective was to examine the microbial changes induced by the supplementation. A total of 40, one-day-old chickens were fed their basal diet for 42 days and then divided into two groups: SG1 (basal diet) and SG2 (basal diet + 10 g/kg Moringa oleifera leaf powder). Metagenomics analysis was conducted to analyze operational taxonomic units (OTUs), species annotation, and biodiversity. Additionally, 16S rRNA sequencing was performed for molecular characterization of isolated gut bacteria, identified as Enterococcus faecium. The isolated bacteria were tested for essential metabolites, demonstrating antibacterial, antioxidant, and anticancer activities. The analysis revealed variations in the microbial composition between the control group (SG1) and the M. oleifera-treated group (SG2). SG2 showed a 47% increase in Bacteroides and a 30% decrease in Firmicutes, Proteobacteria, Actinobacteria, and Tenericutes compared to SG1. TM7 bacteria were observed exclusively in the M. oleifera-treated group. These findings suggest that Moringa oleifera leaf powder acts as a modulator that enhances chicken gut microbiota, promoting the colonization of beneficial bacteria. PICRUSt analysis supported these findings, showing increased carbohydrate and lipid metabolism in the M.oleifera-treated gut microbiota. This study indicates that supplementing chicken feed with Moringa oleifera leaf powder as a phytobiotic enhances the gut microbiota in chicken models, potentially improving overall health. The observed changes in bacterial composition, increased presence of Bacteroides, and exclusive presence of TM7 bacteria suggest a positive modulation of microbial balance. The essential metabolites from isolated Enterococcus faecium bacteria further support the potential benefits of Moringa oleifera supplementation.

A274 THE EFFECT OF DIETARY MODULATION ON FUNGAL AND VIRAL COMMUNITIES IN THE GASTROINTESTINAL TRACT: A LITERATURE REVIEW

Abstract Background The human gut microbiome is a complex, dynamic community that has been shown to impact gastrointestinal (GI) diseases, including inflammatory bowel disease (IBD). Particularly, changes in diet quality and composition can influence the composition and function of the gut microbiome, leading to an inappropriate response to inflammation, increasing risk for IBD flare. Currently, our understanding of diet modulation largely revolves around changes in bacterial composition and diversity, despite our knowledge of neighbouring eukaryotes, viruses, and archaea within the GI tract. This literature review serves to bolster our understanding of diet modulation on viral and fungal communities, in an effort to support non-pharmacological therapies in IBD. Purpose To assess current literature investigating the effect of diet modulation on the gut microbiota, with interest in viral and fungal communities. Method We performed a MEDLINE and EMBASE literature review with the following search terms: "microbiome / microbiota / microbe" and "fungi / fungal" or "virus / viral / virome" and "diet composition" or "high fiber/re diet" or "diet therapy" or "diet." Exclusion criteria: - Abstracts - Articles not in English - Expert Review articles - Articles investigating bacterial microbiota communities exclusively Result(s) Our EMBASE and MEDLINE search identified 418 and 343 articles, respectively. After applying our exclusion criteria and removing duplicates, 13 articles were included (5 - fungal communities exclusively, 4 - viral communities exclusively, 4 - both). Novel research directly investigating the impact of diet modulation on fungal and viral communities in the gut microbiota are exceedingly rare. Despite this, both communities in animal and human models showed increases in diversity in response to diet modulation, independent of changes in bacterial composition. Fungal communities in animal studies showed a four-fold increase in diversity with changes in diet composition (standard chow to high-grain/ high fibre /low fat) as soon as 28 days post dietary commencement. In human studies, fungal communities changed in response to short term diet changes, not long-term. Candida was positively correlated with carbohydrate ingestion, while Aspergillus was negatively correlated with short chain fatty acid ingestion. Viral communities in animal models showed a similar increase in diversity in response to diet modulation (standard chow to high-grain/high-fibre). In human studies, virome response to diet increased most significantly in those with lower initial viral diversity. However, viral diversity was impacted most by interpersonal variation, not diet modulation. Conclusion(s) Diet modulation remains a key player in altering the gut microbiome, extending to fungal and viral communities. Further studies are required to elucidate the magnitude and temporal effect on these lesser studied microbial communities, given recent studies showing the importance of fungal/viral microbes in IBD. Please acknowledge all funding agencies by checking the applicable boxes below None Disclosure of Interest None Declared NEUROGASTROENTEROLOGY &amp; MOTILITY

Polycystic ovary syndrome and iron overload: biochemical link and underlying mechanisms with potential novel therapeutic avenues.

Polycystic ovary syndrome (PCOS) is an endocrine and metabolic disorder in women with components of significant genetic predisposition and possibly multiple, but not yet clearly defined, triggers. This disorder shares several clinical features with hemochromatosis, a genetically defined inheritable disorder of iron overload, which includes insulin resistance, increased adiposity, diabetes, fatty liver, infertility, and hyperandrogenism. A notable difference between the two disorders, however, is that the clinical symptoms in PCOS appear at much younger age whereas they become evident in hemochromatosis at a much later age. Nonetheless, noticeable accumulation of excess iron in the body is a common finding in both disorders even at adolescence. Hepcidin, the iron-regulatory hormone secreted by the liver, is reduced in both disorders and consequently increases intestinal iron absorption. Recent studies have shown that gut bacteria play a critical role in the control of iron absorption in the intestine. As dysbiosis is a common finding between PCOS and hemochromatosis, changes in bacterial composition in the gut may represent another cause for iron overload in both diseases via increased iron absorption. This raises the possibility that strategies to prevent accumulation of excess iron with iron chelators and/or probiotics may have therapeutic potential in the management of polycystic ovary syndrome.