Black Soldier Fly Larvae Influence Internal and Substrate Bacterial Community Composition Depending on Substrate Type and Larval Density.

Saprophagous fly larvae interact with a rich community of bacteria in decomposing organic matter. Larvae of some species, such as the black soldier fly, can process a wide range of organic residual streams into edible insect biomass and thus produce protein as a sustainable component of livestock feed. The microbiological safety of the insects and substrates remains a point of concern. Substrate-associated bacteria can dominate the larval gut microbiota, but the larvae can also alter the bacterial community in the substrate. However, the relative importance of substrate type and larval density in bacterial community dynamics is unknown. We investigated four larval densities (0 [control], 50, 100, or 200 larvae per container [520 mL; diameter, 75 mm]) and three feed substrates (chicken feed, chicken manure, and camelina substrate [50% chicken feed, 50% camelina oilseed press cake]) and sampled the bacterial communities of the substrates and larvae at three time points over 15 days. Although feed substrate was the strongest driver of microbiota composition over time, larval density significantly altered the relative abundances of several common bacterial genera, including potential pathogens, in each substrate and in larvae fed chicken feed. Bacterial communities of the larvae and substrate differed to a higher degree in chicken manure and camelina than in chicken feed. This supports the substrate-dependent impact of black soldier fly larvae on bacteria both within the larvae and in the substrate. This study indicates that substrate composition and larval density can alter bacterial community composition and might be used to improve insect microbiological safety. IMPORTANCE Black soldier fly larvae can process organic side streams into nutritious insect biomass, yielding a sustainable ingredient of animal feed. In processing such organic residues, the larvae impact the substrate and its microbiota. However, their role relative to the feed substrate in shaping the bacterial community is unknown. This may be important for the waste management industry to determine whether pathogens can be controlled by manipulating the larval density and the timing of harvest. We investigated how the type of feed substrate and the larval density (number of larvae per container) interacted to influence bacterial community composition in the substrates and larvae over time. Substrate type was the strongest driver of bacterial community composition, and the magnitude of the impact of the larvae depended on the substrate type and larval density. Thus, both substrate composition and larval density may be used to improve the microbiological safety of the larvae as animal feed.

Fecal Microbiota Signatures Are Not Consistently Related to Symptom Severity in Irritable Bowel Syndrome.

BACKGROUND: Irritable bowel syndrome (IBS) is the most prevalent functional bowel disorder, but its pathophysiology is still unknown. Although a microbial signature associated with IBS severity has been suggested, its association with IBS severity still remains largely unknown. AIMS: This study aims to assess longitudinal dynamics of fecal microbiota and short-chain fatty acids (SCFAs) in different IBS severity groups and study the association with stool pattern, diet, depression, anxiety, and quality of life (QoL). METHODS: A longitudinal study was performed, including n = 91 IBS patients and n = 28 matched controls. All participants collected fecal samples for microbiota composition and SCFA analysis and completed validated questionnaires regarding IBS severity, stool pattern, depression, anxiety, and IBS-QoL at two timepoints with four weeks in-between. Diet was assessed at the first timepoint. RESULTS: Over time, 36% of IBS patients changed in severity group, and 53% changed in predominant stool pattern. The largest proportion of microbiota variation was explained by the individual (R2 = 70.07%). Microbiota alpha diversity and composition, and SCFAs did not differ between IBS severity groups, nor between IBS and controls. Relative abundances of Bifidobacterium, Terrisporobacter, and Turicibacter consistently differed between IBS and controls, but not between IBS severity groups. Large dynamics over time were observed in the association of microbiota composition with questionnaire data where IBS symptom severity was associated at T1 but not at T2. CONCLUSIONS: Fecal microbiota and SCFA signatures were not consistently associated with IBS severity over time, indicating the importance of repeated sampling in IBS research.

The Modified Bristol Stool Form Scale: A Reliable and Valid Tool to Score Stool Consistency in Dutch (Non)Toilet-trained Toddlers.

OBJECTIVE: The aim of the study was to assess whether the modified Bristol Stool Form Scale (m-BSFS) is reliable, valid and user-friendly to use by parents, grandparents, and day childcare employees to evaluate stool consistency in toilet and nontoilet-trained toddlers in the Netherlands. STUDY DESIGN: Translation to Dutch and validity of the m-BSFS (scoring 32 general stool pictures) for 1 to 3 year old toddlers (n = 89) was evaluated by parents, grandparents, and day childcare employees. A subgroup of participants scored an additional 7 pictures of stools in a diaper to validate the m-BSFS for non-toilet-trained toddlers (n = 16). To determine inter-rater reliability, 2-way random effects single-rater intraclass correlation coefficient (ICC)consistency was used. Intra-rater reliability was measured by Cohen kappa (κ) by rating the same pictures in random order twice, with at least 1 week between the first and second scoring. RESULTS: Inter- and intra-rater reliability of the m-BSFS were above recommended minimal standards of 0.61 for the 32 general stool pictures as well as for the 7 pictures of stools in a diaper. ICCconsistency for the general stool pictures of the first and second ratings were 0.71 (n = 89) and 0.79 (n = 77), respectively, with a κ of 0.71 (n = 77). ICCconsistency for the stools in diaper pictures of the first and second ratings were 0.93 (n = 16) and 0.93 (n = 15), respectively, with a κ of 0.77 (n = 15). CONCLUSIONS: The m-BSFS is reliable, valid and user-friendly to use by Dutch-speaking parents, grandparents, and day childcare workers to evaluate stool consistency in both toilet- and nontoilet-trained toddlers in the Netherlands.

Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries.

OBJECTIVE: Ageing is accompanied by deterioration of multiple bodily functions and inflammation, which collectively contribute to frailty. We and others have shown that frailty co-varies with alterations in the gut microbiota in a manner accelerated by consumption of a restricted diversity diet. The Mediterranean diet (MedDiet) is associated with health. In the NU-AGE project, we investigated if a 1-year MedDiet intervention could alter the gut microbiota and reduce frailty. DESIGN: We profiled the gut microbiota in 612 non-frail or pre-frail subjects across five European countries (UK, France, Netherlands, Italy and Poland) before and after the administration of a 12-month long MedDiet intervention tailored to elderly subjects (NU-AGE diet). RESULTS: Adherence to the diet was associated with specific microbiome alterations. Taxa enriched by adherence to the diet were positively associated with several markers of lower frailty and improved cognitive function, and negatively associated with inflammatory markers including C-reactive protein and interleukin-17. Analysis of the inferred microbial metabolite profiles indicated that the diet-modulated microbiome change was associated with an increase in short/branch chained fatty acid production and lower production of secondary bile acids, p-cresols, ethanol and carbon dioxide. Microbiome ecosystem network analysis showed that the bacterial taxa that responded positively to the MedDiet intervention occupy keystone interaction positions, whereas frailty-associated taxa are peripheral in the networks. CONCLUSION: Collectively, our findings support the feasibility of improving the habitual diet to modulate the gut microbiota which in turn has the potential to promote healthier ageing.

Distal colonic transit is linked to gut microbiota diversity and microbial fermentation in humans with slow colonic transit.

Longer colonic transit time and hard stools are associated with increased gut microbiota diversity. Here, we investigate to what extent quantitative measures of (segmental) colonic transit time were related to gut microbiota composition, microbial metabolites, and gut-related parameters in a human cross-sectional study. Using radiopaque markers, (segmental) colonic transit time (CTT) was measured in 48 lean/overweight participants with long colonic transit but without constipation. Fecal microbiota composition was determined using 16S rRNA gene amplicon sequencing. Associations between gastrointestinal transit (segmental CTT and stool frequency and consistency), microbiota diversity and composition, microbial metabolites [short-chain fatty acids (SCFA), branched-chain fatty acids, and breath hydrogen], habitual diet, and gut-related host parameters [lipopolysaccharide-binding protein (LBP) and fecal calprotectin] were investigated using univariate and multivariate approaches. Long descending (i.e., distal) colonic transit was associated with increased microbial α-diversity but not with stool consistency. Using unweighted and weighted UniFrac distance, microbiota variation was not related to (segmental) CTT but to demographics, diet, plasma LBP, and fecal calprotectin. Bray-Curtis dissimilarity related only to stool consistency. Rectosigmoid and descending colonic transit were negatively associated with fecal SCFA and plasma acetate, respectively. This study suggests that the distal colon transit may affect not only microbiota diversity but also microbial metabolism.NEW & NOTEWORTHY We extend previous findings showing that long distal colonic transit time influences microbial diversification and fermentation, whereas stool consistency is related to microbiota composition in humans with a long colonic transit. This study puts the importance of the (distal) colonic site in microbiota ecology forward, which should be considered in future therapeutic studies targeting, for instance, short-chain fatty acid production to improve metabolic health.

Supplementation of Diet With Galacto-oligosaccharides Increases Bifidobacteria, but Not Insulin Sensitivity, in Obese Prediabetic Individuals.

BACKGROUND & AIMS: The gut microbiota affects host lipid and glucose metabolism, satiety, and chronic low-grade inflammation to contribute to obesity and type 2 diabetes. Fermentation end products, in particular the short-chain fatty acid (SCFA) acetate, are believed to be involved in these processes. We investigated the long-term effects of supplementation with galacto-oligosaccharides (GOS), an acetogenic fiber, on the composition of the human gut microbiota and human metabolism. METHODS: We performed a double-blinded, placebo-controlled, parallel intervention study of 44 overweight or obese (body mass index, 28-40 kg/m2) prediabetic men and women (ages, 45-70 y) from October 2014 through October 2015 in Maastricht, The Netherlands. The participants were assigned randomly to groups who ingested 15 g GOS or isocaloric placebo (maltodextrin) daily with their regular meals for 12 weeks. Before and after this period, we collected data on peripheral and adipose tissue insulin sensitivity, fecal microbiota composition, plasma and fecal SCFA, energy expenditure and substrate oxidation, body composition, and hormonal and inflammatory responses. The primary outcome was the effect of GOS on peripheral insulin sensitivity, measured by the hyperinsulinemic-euglycemic clamp method. RESULTS: Supplementation of diets with GOS, but not placebo, increased the abundance of Bifidobacterium species in feces by 5-fold (P = .009; q = 0.144). Microbial richness or diversity in fecal samples were not affected. We did not observe any differences in fecal or fasting plasma SCFA concentrations or in systemic concentrations of gut-derived hormones, incretins, lipopolysaccharide-binding protein, or other markers of inflammation. In addition, no significant alterations in peripheral and adipose tissue insulin sensitivity, body composition, and energy and substrate metabolism were found. CONCLUSIONS: Twelve-week supplementation of GOS selectively increased fecal Bifidobacterium species abundance, but this did not produce significant changes in insulin sensitivity or related substrate and energy metabolism in overweight or obese prediabetic men and women. ClincialTrials.gov number, NCT02271776.

The gut microbiota and host health: a new clinical frontier.

Over the last 10-15 years, our understanding of the composition and functions of the human gut microbiota has increased exponentially. To a large extent, this has been due to new 'omic' technologies that have facilitated large-scale analysis of the genetic and metabolic profile of this microbial community, revealing it to be comparable in influence to a new organ in the body and offering the possibility of a new route for therapeutic intervention. Moreover, it might be more accurate to think of it like an immune system: a collection of cells that work in unison with the host and that can promote health but sometimes initiate disease. This review gives an update on the current knowledge in the area of gut disorders, in particular metabolic syndrome and obesity-related disease, liver disease, IBD and colorectal cancer. The potential of manipulating the gut microbiota in these disorders is assessed, with an examination of the latest and most relevant evidence relating to antibiotics, probiotics, prebiotics, polyphenols and faecal microbiota transplantation.

Variation in the Conservation of Species-Specific Gene Sets for HMO Degradation and Its Effects on HMO Utilization in Bifidobacteria.

Human milk provides essential nutrients for infants but also consists of human milk oligosaccharides (HMOs), which are resistant to digestion by the infant. Bifidobacteria are among the first colonizers, providing various health benefits for the host. This is largely facilitated by their ability to efficiently metabolize HMOs in a species-specific way. Nevertheless, these abilities can vary significantly by strain, and our understanding of the mechanisms applied by different strains from the same species remains incomplete. Therefore, we assessed the effects of strain-level genomic variation in HMO utilization genes on growth on HMOs in 130 strains from 10 species of human associated bifidobacteria. Our findings highlight the extent of genetic diversity between strains of the same species and demonstrate the effects on species-specific HMO utilization, which in most species is largely retained through the conservation of a core set of genes or the presence of redundant pathways. These data will help to refine our understanding of the genetic factors that contribute to the persistence of individual strains and will provide a better mechanistic rationale for the development and optimization of new early-life microbiota-modulating products to improve infant health.

Seeding the Infant Gut in Early Life-Effects of Maternal and Infant Seeding with Probiotics on Strain Transfer, Microbiota, and Gastrointestinal Symptoms in Healthy Breastfed Infants.

We investigated the effects of two dosing regimens of two multi-strain probiotic products on the gut microbiota of breastfed infants, including the transfer of the dosed strains and clinical outcomes. In forty-seven dyads, infants were either exposed through maternal intake (MS) of Lactobacillus acidophilus LA-5, Bifidobacterium animalis subsp. lactis BB-12, Lacticaseibacillus rhamnosus LGG, and Bifidobacterium longum subsp. infantis Bifin02 from gestational week thirty-three until four weeks after birth (n = 24) or dosed directly (IS) with the same strains except for LA-5 starting within 24 h after birth until day 28 (n = 23). Infant stool samples were collected on day 0, 14, 28, and 42 after birth. Gastrointestinal symptoms were assessed by parents using an electronic diary. Microbiota composition was determined using 16S rRNA sequencing, and strain recovery was analyzed by qPCR. Notably, 100% of the IS infants were colonized with Bifin02 after 14 days as opposed to only 25% of the MS infants. Mean stool frequency was significantly lower in IS infants compared to MS infants and IS infants had softer stools on day 14, 28, and 42. A significantly steeper slope of progression of inconsolable crying and fussing was observed in MS infants compared to IS infants. In conclusion, direct infant seeding induced a faster increase in fecal bifidobacteria abundancy and Bifin02 recovery compared to dosed through the maternal intake.

Infant Formula Supplemented with Five Human Milk Oligosaccharides Shifts the Fecal Microbiome of Formula-Fed Infants Closer to That of Breastfed Infants.

Breastmilk is the optimal source of infant nutrition, with short-term and long-term health benefits. Some of these benefits are mediated by human milk oligosaccharides (HMOs), a unique group of carbohydrates representing the third most abundant solid component of human milk. We performed the first clinical study on infant formula supplemented with five different HMOs (5HMO-mix), comprising 2'-fucosyllactose, 3-fucosyllactose, lacto-N-tetraose, 3'-sialyllactose and 6'-sialyllactose at a natural total concentration of 5.75 g/L, and here report the analysis of the infant fecal microbiome. We found an increase in the relative abundance of bifidobacteria in the 5HMO-mix cohort compared with the formula-fed control, specifically affecting bifidobacteria that can produce aromatic lactic acids. 5HMO-mix influenced the microbial composition as early as Week 1, and the observed changes persisted to at least Week 16, including a relative decrease in species with opportunistic pathogenic strains down to the level observed in breastfed infants during the first 4 weeks. We further analyzed the functional potential of the microbiome and observed features shared between 5HMO-mix-supplemented and breastfed infants, such as a relative enrichment in mucus and tyrosine degradation, with the latter possibly being linked to the aromatic lactic acids. The 5HMO-mix supplement, therefore, shifts the infant fecal microbiome closer to that of breastfed infants.

In Vitro Screening for Probiotic Properties of Lactobacillus and Bifidobacterium Strains in Assays Relevant for Non-Alcoholic Fatty Liver Disease Prevention.

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial metabolic disorder that poses health challenges worldwide and is expected to continue to rise dramatically. NAFLD is associated with metabolic syndrome, type 2 diabetes mellitus, and impaired gut health. Increased gut permeability, caused by disturbance of tight junction proteins, allows passage of damaging microbial components that, upon reaching the liver, have been proposed to trigger the release of inflammatory cytokines and generate cellular stress. A growing body of research has suggested the utilization of targeted probiotic supplements as a preventive therapy to improve gut barrier function and tight junctions. Furthermore, specific microbial interactions and metabolites induce the secretion of hormones such as GLP-1, resulting in beneficial effects on liver health. To increase the likelihood of finding beneficial probiotic strains, we set up a novel screening platform consisting of multiple in vitro and ex vivo assays for the screening of 42 bacterial strains. Analysis of transepithelial electrical resistance response via co-incubation of the 42 bacterial strains with human colonic cells (Caco-2) revealed improved barrier integrity. Then, strain-individual metabolome profiling was performed revealing species-specific clusters. GLP-1 secretion assay with intestinal secretin tumor cell line (STC-1) found at least seven of the strains tested capable of enhancing GLP-1 secretion in vitro. Gene expression profiling in human biopsy-derived intestinal organoids was performed using next generation sequencing transcriptomics post bacterial co-incubation. Here, different degrees of immunomodulation by the increase in certain cytokine and chemokine transcripts were found. Treatment of mouse primary hepatocytes with selected highly produced bacterial metabolites revealed that indole metabolites robustly inhibited de novo lipogenesis. Collectively, through our comprehensive bacterial screening pipeline, not previously ascribed strains from both Lactobacillus and Bifidobacterium genera were proposed as potential probiotics based on their ability to increase epithelial barrier integrity and immunity, promote GLP-1 secretion, and produce metabolites relevant to liver health.

Conserved developmental trajectories of the cecal microbiota of broiler chickens in a field study.

There is great interest in identifying gut microbiota development patterns and underlying assembly rules that can inform strategies to improve broiler health and performance. Microbiota stratification using community types helps to simplify complex and dynamic ecosystem principles of the intestinal microbiota. This study aimed to identify community types to increase insight in intestinal microbiota variation between broilers and to identify factors that explain this variation. A total of 10 well-performing poultry flocks on four farms were followed. From each flock, the cecal content of nine broilers was collected at 7, 14, and 35 days posthatch. A total of two robust community types were observed using different clustering methods, one of which was dominated by 7-day-old broilers, and one by 35-day-old broilers. Broilers, 14-day-old, were divided across both community types. This is the first study that showed conserved cecal microbiota development trajectories in commercial broiler flocks. In addition to the temporal development with age, the cecal microbiota variation between broilers was explained by the flock, body weight, and the different feed components. Our data support a conserved development of cecal microbiota, despite strong influence of environmental factors. Further investigation of mechanisms underlying microbiota development and function is required to facilitate intestinal health promoting management, diagnostics, and nutritional interventions.

Selective pressure on microbial communities in a drinking water aquifer - Geochemical parameters vs. micropollutants.

Groundwater quality is crucial for drinking water production, but groundwater resources are increasingly threatened by contamination with pesticides. As pesticides often occur at micropollutant concentrations, they are unattractive carbon sources for microorganisms and typically remain recalcitrant. Exploring microbial communities in aquifers used for drinking water production is an essential first step towards understanding the fate of micropollutants in groundwater. In this study, we investigated the interaction between groundwater geochemistry, pesticide presence, and microbial communities in an aquifer used for drinking water production. Two groundwater monitoring wells in The Netherlands were sampled in 2014, 2015, and 2016. In both wells, water was sampled from five discrete depths ranging from 13 to 54 m and was analyzed for geochemical parameters, pesticide concentrations and microbial community composition using 16S rRNA gene sequencing and qPCR. Groundwater geochemistry was stable throughout the study period and pesticides were heterogeneously distributed at low concentrations (µg L-1 range). Microbial community composition was also stable throughout the sampling period. Integration of a unique dataset of chemical and microbial data showed that geochemical parameters and to a lesser extent pesticides exerted selective pressure on microbial communities. Microbial communities in both wells showed similar composition in the deeper aquifer, where pumping results in horizontal flow. This study provides insight into groundwater parameters that shape microbial community composition. This information can contribute to the future implementation of remediation technologies to guarantee safe drinking water production.

Methanogen Levels Are Significantly Associated with Fecal Microbiota Composition and Alpha Diversity in Healthy Adults and Irritable Bowel Syndrome Patients.

Hydrogenotrophic microbes, primarily including the three functional groups methanogens, sulfate-reducing bacteria, and reductive acetogens, use hydrogen as an energy source and play an important role in maintaining the hydrogen balance in gut ecosystems. A distorted hydrogen balance has been associated with irritable bowel syndrome (IBS). However, the role of hydrogenotrophic microbes in overall microbiota composition and function remains largely unknown. This study aims to assess the distribution and stability of hydrogenotrophic functional groups in healthy adults (HAs) and IBS patients and their association with overall microbiota composition and IBS symptoms. A two-time-point study with 4 weeks in between was performed with 27 HAs and 55 IBS patients included. Our observations revealed that methanogens showed a bimodal distribution across samples. A high-level methanogen microbiota was consistently associated with higher alpha diversity, and its composition was significantly different from that of individuals with a low-level methanogen microbiota. In general, these associations were more pronounced in IBS patients than in HAs. The differences in the copy numbers of genes indicative of total bacteria and acetogens between HAs and IBS patients and their correlations with IBS symptom severity, anxiety, depression, and quality of life (QoL) were sampling time dependent. Hydrogenotrophic functional groups did not show negative abundance correlations with each other in HAs and IBS patients. These findings suggest that methanogen levels in the gut have a pronounced association with microbiota alpha diversity and composition, and the interactions between hydrogenotrophic functional groups are complex in gut ecosystems. IMPORTANCE Hydrogenotrophic microbes play an essential role in the disposal of hydrogen and the maintenance of the hydrogen balance in gut ecosystems. Their abundances vary between individuals and have been reported to be associated with human gut disorders such as irritable bowel disease. This study confirms that methanogen levels show a bimodal distribution. Moreover, a high-level methanogen microbiota was associated with higher alpha diversity, and its composition was different from that of individuals with a low-level methanogen microbiota. These associations are more pronounced in IBS patients than in healthy subjects. In addition, associations between hydrogenotrophic microbes and IBS symptom scores vary over time, which argues for the use of longitudinal study designs. Last but not least, this study suggests that the different hydrogenotrophic microbes coexist with each other and do not necessarily compete for hydrogen in the gut. The findings in this study highlight the impact of methanogens on overall microbiota composition and function.

Fiber mixture-specific effect on distal colonic fermentation and metabolic health in lean but not in prediabetic men.

Infusions of the short-chain fatty acid (SCFA) acetate in the distal colon improved metabolic parameters in men. Here, we hypothesized that combining rapidly and slowly fermentable fibers will enhance distal colonic acetate production and improve metabolic health. In vitro cultivation studies in a validated model of the colon were used to identify fiber mixtures that yielded high distal colonic acetate production. Subsequently, in two randomized crossover studies, lean and prediabetic overweight/obese men were included. In one study, participants received supplements of either long-chain inulin+resistant starch (INU+RS), INU or maltodextrin (PLA) the day prior to a clinical investigation day (CID). The second trial studied beta glucan+RS (BG+RS) versus BG and PLA. During each CID, breath hydrogen, indirect calorimetry, plasma metabolites/hormones were assessed during fasting and postprandial conditions. Additionally, fecal microbiota composition and SCFA were determined. In prediabetic men, INU+RS increased plasma acetate compared to INU or PLA (P < .05), but did not affect metabolic parameters. In lean men, INU+RS increased breath hydrogen and fasting plasma butyrate, which was accompanied by increased energy expenditure, carbohydrate oxidation and PYY and decreased postprandial glucose concentrations (all P < .05) compared to PLA. BG+RS increased plasma butyrate compared to PLA (P < .05) in prediabetic individuals, but did not affect other fermentation/metabolic markers in both phenotypes. Fiber-induced shifts in fecal microbiota were individual-specific and more pronounced with INU+RS versus BG+RS. Administration of INU+RS (not BG+RS) the day prior to investigation improved metabolic parameters in lean but not in prediabetic individuals, demonstrating that effects were phenotype- and fiber-specific. Further research should study whether longer-term supplementation periods are required to elicit beneficial metabolic health in prediabetic individuals. Trial registration numbers: Clinical trial No. NCT03711383 (Inulin study) and Clinical trial No. NCT03714646 (Beta glucan study).

Free Faecal Water: Analysis of Horse Faecal Microbiota and the Impact of Faecal Microbial Transplantation on Symptom Severity.

Free faecal water (FFW) in equines results in pollution of the hindquarters and tail and can also involve clinical signs. Though the cause of FFW is unknown, it was hypothesized that it may involve the gut microbiota. This hypothesis was addressed as follows. First, the faecal prokaryotic community composition of horses suffering from FFW relative to healthy controls (n = 10) was compared. Second, FFW horses were treated with a standardised faecal microbiota transplantation (FMT) protocol (n = 10), followed by assessment of FFW symptom severity and faecal prokaryotic community composition over a follow-up period of 168 days. No significant differences were found in the faecal microbiota composition of FFW horses compared to healthy controls (p > 0.05). Relative to before FMT, FFW symptom severity decreased in affected horses 14 days after FMT (p = 0.02) and remained decreased for the remainder of the study (p < 0.02). However, individual animal responses to FMT varied. FMT had no effect on FFW horse faecal prokaryotic community composition in terms of alpha or beta diversity. Alpha diversity of the donor inocula used in the FMT was always lower than that of the faecal microbiota of the FFW treated horses (p < 0.001). In conclusion, whilst findings indicate FFW horses do not have an altered hindgut microbiota, some horses that received FMT had a temporary alleviation of FFW symptom severity without causing changes in the faecal microbiota. Future studies using controls are now needed to confirm the effectiveness of FMT to treat FFW.

Biofouling control: the impact of biofilm dispersal and membrane flushing.

Pure culture studies have shown that biofilm dispersal can be triggered if the nutrient supply is discontinued by stopping the flow. Stimulating biofilm dispersal in this manner would provide a sustainable manner to control unwanted biofilm growth in industrial settings, for instance on synthetic membranes used to purify water. The response of multispecies biofilms to nutrient limitation has not been thoroughly studied. To assess biomass dispersal during nutrient limitation it is common practise to flush the biofilm after a stop-period. Hence, flow-stop-induced biomass removal could occur as a response to nutrient limitation followed by mechanical removal due to biofilm flushing (e.g. biofilm detachment). Here, we investigated the feasibility to reduce membrane biofouling by stopping the flow and flushing the membrane. Using a membrane fouling simulator, biomass removal from synthetic membranes after different stop-periods was determined, as well as biomass removal at different cross flow velocities. Biomass removal from membrane surfaces depended on the nutrient limiting period and on the flow velocity during the biofilm flush. When flushed at a low flow velocity (0.1 m.s-1), the duration of the stop-period had a large effect on the biomass removal rate, but when the flow velocity was increased to 0.2 m.s-1, the length of the stop period became less considerable. The flow velocity during membrane flushing has an effect on the bacterial community that colonized the membranes afterwards. Repetition of the stop-period and biofilm flushing after three repetitive biofouling cycles led to a stable bacterial community. The increase in bacterial community stability coincided with a decrease in cleaning effectivity to restore membrane performance. This shows that membrane cleaning comes at the costs of a more stable bacterial community that is increasingly difficult to remove.

Relative contributions of egg-associated and substrate-associated microorganisms to black soldier fly larval performance and microbiota.

Larvae of the black soldier fly (BSF) can be used to convert organic waste into insect biomass for animal feed. In this process, they interact with microorganisms originating from the substrate, the insect and the environment. The substrate is the main determinant of the larval gut microbiota composition, but inoculation of the substrate with egg-associated bacteria can improve larval performance. We aimed to quantify the relative importance of substrate-associated and egg-associated microorganisms in BSF larval performance, bacterial abundance and bacterial community composition, when larvae were fed with chicken feed or chicken manure. For this, we inactivated substrate-associated microorganisms by autoclaving, or disinfected BSF eggs. Larval survival, weight and proportion of prepupae were determined on day 15. We collected substrate and larval samples on days 0 and 15 and performed 16S rRNA gene-targeted qPCR and amplicon sequencing. In both chicken feed and chicken manure, egg disinfection did not cause any difference in larval performance or overall microbiota composition. In contrast, in chicken manure, substrate-associated microorganisms increased larval biomass and sterilizing the substrate caused major shifts in microbiota. Thus, substrate-associated microorganisms impact not only larval microbiota but also larval performance, whereas egg-associated microorganisms have a minor role in the densities present.

Structure-Specific Fermentation of Galacto-Oligosaccharides, Isomalto-Oligosaccharides and Isomalto/Malto-Polysaccharides by Infant Fecal Microbiota and Impact on Dendritic Cell Cytokine Responses.

SCOPE: Next to galacto-oligosaccharides (GOS), starch-derived isomalto-oligosaccharide preparation (IMO) and isomalto/malto-polysaccharides (IMMP) could potentially be used as prebiotics in infant formulas. However, it remains largely unknown how the specific molecular structures of these non-digestible carbohydrates (NDCs) impact fermentability and immune responses in infants. METHODS AND RESULTS: In vitro fermentation of GOS, IMO and IMMP using infant fecal inoculum of 2- and 8-week-old infants shows that only GOS and IMO are fermented by infant fecal microbiota. The degradation of GOS and IMO coincides with an increase in Bifidobacterium and production of acetate and lactate, which is more pronounced with GOS. Individual isomers with an (1↔1)-linkage or di-substituted reducing terminal glucose residue are more resistant to fermentation. GOS, IMO, and IMMP fermentation digesta attenuates cytokine profiles in immature dendritic cells (DCs), but the extent is dependent on the infants age and NDC structure. CONCLUSION: The IMO preparation, containing reducing and non-reducing isomers, shows similar fermentation patterns as GOS in fecal microbiota of 2-week-old infants. Knowledge obtained on the substrate specificities of infant fecal microbiota and the subsequent regulatory effects of GOS, IMO and IMMP on DC responses might contribute to the design of tailored NDC mixtures for infants of different age groups.

Does entry to center-based childcare affect gut microbial colonization in young infants?

Entry to center-based childcare (CC) at three months of life can be an important challenge for infants as it includes major stressors such as long maternal separations and frequently changing caregivers. Stress and the new environment may in turn alter the composition of the gut microbiota with possible implications for future health outcomes. As part of an ongoing longitudinal study, we investigated whether CC, as compared to being cared for by the parents at home, alters the composition of the gut microbiota, while accounting for known covariates of the infant gut microbiota. Stool samples of infants who entered CC (n = 49) and control infants (n = 49) were obtained before and four weeks after CC entrance. Using Redundancy analysis, Random Forests and Bayesian linear models we found that infant gut microbiota was not affected in a uniform way by entry to CC. In line with the literature, breastfeeding, birth mode, age, and the presence of siblings were shown to significantly impact the microbial composition.