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We describe the technology and validation of a new whole room indirect calorimeter (WRIC) methodology to quantify volume of methane (VCH4) released from the human body over 24 h concurrently with the assessment of energy expenditure and substrate utilization. The new system extends the assessment of energy metabolism by adding CH4, a downstream product of microbiome fermentation that could contribute to energy balance. Our new system consists of an established WRIC combined with the addition of off-axis integrated-cavity output spectroscopy (OA-ICOS) to measure CH4 concentration ([CH4]). Development, validation, and reliability of the system included environmental experiments to measure the stability of the atmospheric [CH4], infusing CH4 into the WRIC and human cross-validation studies comparing [CH4] quantified by OA-ICOS and mid-infrared dual-comb spectroscopy (MIR DCS). Our infusion data indicated that the system measured 24-h [CH4] and VCH4 with high sensitivity, reliability, and validity. Cross-validation studies showed good agreement between OA-ICOS and MIR DCS technologies (r = 0.979, P < 0.0001). Human data revealed 24-h VCH4 was highly variable between subjects and within/between days. Finally, our method to quantify VCH4 released by breath or colon suggested that over 50% of the CH4 was eliminated through the breath. The method allows, for the first time, measurement of 24-h VCH4 (in kcal) and therefore the measurement of the proportion of human energy intake fermented to CH4 by the gut microbiome and released via breath or from the intestine; also, it allows us to track the effects of dietary, probiotic, bacterial, and fecal microbiota transplantation on VCH4. NEW & NOTEWORTHY This is the first time that continuous assessment of CH4 is reported in parallel with measurements of O2 consumption and CO2 production inside a whole room indirect calorimeter in humans and over 24 h. We provide a detailed description of the whole system and its parts. We carried out studies of reliability and validity of the whole system and its parts. CH4 is released in humans during daily activities. [ABSTRACT FROM AUTHOR]

Abstract Background Buffering to achieve pH control is crucial for successful trichloroethene (TCE) anaerobic bioremediation. Bicarbonate (HCO3−) is the natural buffer in groundwater and the buffer of choice in the laboratory and at contaminated sites undergoing biological treatment with organohalide respiring microorganisms. However, HCO3− also serves as the electron acceptor for hydrogenotrophic methanogens and hydrogenotrophic homoacetogens, two microbial groups competing with organohalide respirers for hydrogen (H2). We studied the effect of HCO3− as a buffering agent and the effect of HCO3−-consuming reactions in a range of concentrations (2.5-30 mM) with an initial pH of 7.5 in H2-fed TCE reductively dechlorinating communities containing Dehalococcoides, hydrogenotrophic methanogens, and hydrogenotrophic homoacetogens. Results Rate differences in TCE dechlorination were observed as a result of added varying HCO3− concentrations due to H2-fed electrons channeled towards methanogenesis and homoacetogenesis and pH increases (up to 8.7) from biological HCO3− consumption. Significantly faster dechlorination rates were noted at all HCO3− concentrations tested when the pH buffering was improved by providing 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) as an additional buffer. Electron balances and quantitative PCR revealed that methanogenesis was the main electron sink when the initial HCO3− concentrations were 2.5 and 5 mM, while homoacetogenesis was the dominant process and sink when 10 and 30 mM HCO3− were provided initially. Conclusions Our study reveals that HCO3− is an important variable for bioremediation of chloroethenes as it has a prominent role as an electron acceptor for methanogenesis and homoacetogenesis. It also illustrates the changes in rates and extent of reductive dechlorination resulting from the combined effect of electron donor competition stimulated by HCO3− and the changes in pH exerted by methanogens and homoacetogens.

Food crops around the world are commonly contaminated with Aspergillus flavus , which can produce the carcinogenic mycotoxin aflatoxin B1 (AFB1). The objective of this study is to test an X-ray irradiation sterilization method for studying AFB1 in contaminated maize samples in the laboratory. Maize that had been naturally contaminated with 300 ppb AFB1 by the growth of aflatoxigenic A. flavus was ground and then irradiated at 0.0, 1.0, 1.5, 2.0, 2.5, and 3.0 kGy. A. flavus was quantified by dilution plating on potato dextrose agar (PDA) and modified Rose Bengal media (MDRB) for viability and qPCR for gene presence. AFB1 was quantified by HPLC and ELISA. A. flavus viability, but not gene copies, significantly decreased with increasing doses of radiation (PDA: p < 0.001; MDRB: p < 0.001; qPCR: p = 0.026). AFB1 concentration did not significantly change with increasing doses of radiation (HPLC: p = 0.153; ELISA: p = 0.567). Our results imply that X-ray irradiation is an effective means of reducing viable A. flavus without affecting AFB1 concentrations. Reducing the hazard of fungal spores and halting AFB1 production at the targeted dose are important steps to safely and reproducibly move forward research on the global mycotoxin challenge.

Biodegradation of 1,4-Dioxane at environmentally relevant concentrations usually requires the addition of a primary electron-donor substrate to sustain biomass growth. Ethane is a promising substrate, since it is available as a degradation product of 1,4-Dioxane's common co-contaminants. This study reports kinetic parameters for ethane biodegradation and co-oxidations of ethane and 1,4-Dioxane. Based on experiments combined with mathematical modeling, we found that ethane promoted 1,4-Dioxane biodegradation when the initial mass ratio of ethane:1,4-Dioxane was < 9:1 mg COD/mg COD, while it inhibited 1,4-Dioxane degradation when the ratio was > 9:1. A model-independent estimator was used for kinetic-parameter estimation, and all parameter values for 1,4-Dioxane were consistent with literature-reported ranges. Estimated parameters support competitive inhibition between ethane as the primary substrate and 1,4-Dioxane as the secondary substrate. The results also support that bacteria that co-oxidize ethane and 1,4-Dioxane had a competitive advantage over bacteria that can use only one of the two substrates. The minimum concentration of ethane to sustain ethane-oxidizing bacteria and ethane and 1,4-Dioxane-co-oxidizing bacteria was 0.09 mg COD/L, which is approximately 20-fold lower than the minimum concentration reported for propane, another common substrate used to promote 1,4-Dioxane biodegradation. The minimum 1,4-Dioxane concentration required to sustain steady-state biomass with 1,4-Dioxane as the sole primary substrate was 1.3 mg COD/L. As 1,4-Dioxane concentrations at most groundwater sites are less than 0.18 mg COD/L, providing ethane as a primary substrate is vital to support biomass growth and consequently enable 1,4-Dioxane bioremediation., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

The gut microbiome (GM) modulates body weight/composition and gastrointestinal functioning; therefore, approaches targeting resident gut microbes have attracted considerable interest. Intermittent fasting (IF) and protein pacing (P) regimens are effective in facilitating weight loss (WL) and enhancing body composition. However, the interrelationships between IF- and P-induced WL and the GM are unknown. The current randomized controlled study describes distinct fecal microbial and plasma metabolomic signatures between combined IF-P (n = 21) versus a heart-healthy, calorie-restricted (CR, n = 20) diet matched for overall energy intake in free-living human participants (women = 27; men = 14) with overweight/obesity for 8 weeks. Gut symptomatology improves and abundance of Christensenellaceae microbes and circulating cytokines and amino acid metabolites favoring fat oxidation increase with IF-P (p < 0.05), whereas metabolites associated with a longevity-related metabolic pathway increase with CR (p < 0.05). Differences indicate GM and metabolomic factors play a role in WL maintenance and body composition. This novel work provides insight into the GM and metabolomic profile of participants following an IF-P or CR diet and highlights important differences in microbial assembly associated with WL and body composition responsiveness. These data may inform future GM-focused precision nutrition recommendations using larger sample sizes of longer duration. Trial registration, March 6, 2020 (ClinicalTrials.gov as NCT04327141), based on a previous randomized intervention trial., (© 2024. The Author(s).)

The efficacy of prebiotics and probiotics (synbiotics when combined) to improve symptoms associated with autism spectrum disorder (ASD) has shown considerable inter-study variation, likely due to the complex, heterogeneous nature of the disorder and its associated behavioral, developmental, and gastrointestinal symptoms. Here, we present a precision synbiotic supplementation study in 296 children and adults diagnosed with ASD versus 123 age-matched neurotypical controls. One hundred seventy ASD participants completed the study. Baseline and post-synbiotic assessment of ASD and gastrointestinal (GI) symptoms and deep metagenomic sequencing were performed. Within the ASD cohort, there were significant differences in microbes between subpopulations based on the social responsiveness scale (SRS2) survey ( Prevotella spp. , Bacteroides, Fusicatenibacter , and others) and gluten and dairy-free diets ( Bifidobacterium spp., Lactococcus, Streptococcus spp., and others). At the baseline, the ASD cohort maintained a lower taxonomic alpha diversity and significant differences in taxonomic composition, metabolic pathways, and gene families, with a greater proportion of potential pathogens, including Shigella, Klebsiella, and Clostridium, and lower proportions of beneficial microbes, including Faecalibacterium compared to controls. Following the 3-month synbiotic supplementation, the ASD cohort showed increased taxonomic alpha diversity, shifts in taxonomy and metabolic pathway potential, and improvements in some ASD-related symptoms, including a significant reduction in GI discomfort and overall improved language, comprehension, cognition, thinking, and speech. However, the open-label study design may include some placebo effects. In summary, we found that precision synbiotics modulated the gut microbiome and could be used as supplementation to improve gastrointestinal and ASD-related symptoms., Importance: Autism spectrum disorder (ASD) is prevalent in 1 out of 36 children in the United States and contributes to health, financial, and psychological burdens. Attempts to identify a gut microbiome signature of ASD have produced varied results. The limited pre-clinical and clinical population sizes have hampered the success of these trials. To understand the microbiome associated with ASD, we employed whole metagenomic shotgun sequencing to classify microbial composition and genetic functional potential. Despite being one of the most extensive ASD post-synbiotic assessment studies, the results highlight the complexity of performing such a case-control supplementation study in this population and the potential for a future therapeutic approach in ASD., Competing Interests: J.P., D.N., S.J., T.M., S.D., K.B., and S.T. are employed by Sun Genomics Inc. D.C.C. was co-supported by Sun Genomics Inc. J.A. and R.K.-B. are co-founders of Gut-Brain Axis Therapeutics Inc., which is developing microbiome-based treatments for autism and other disorders.

Traditional research on biodegradation of emerging organic pollutants involves slow and labor-intensive experimentation. Currently, fast-developing metagenome, metatranscriptome, and metabolome technologies promise to expedite mechanistic research on biodegradation of emerging organic pollutants. Integrating the metagenome, metatranscriptome, and metabolome (i.e., tri-omics) makes it possible to link gene abundance and expression with the biotransformation of the contaminant and the formation of metabolites from this biotransformation. In this study, we used this tri-omics approach to study the biotransformation pathways for cetyltrimethylammonium bromide (CTAB) under aerobic conditions. The tri-omics analysis showed that CTAB undergoes three parallel first-step mono-/di-oxygenations (to the α, β, and ω-carbons); intermediate metabolites and expressed enzymes were identified for all three pathways, and the β-carbon mono-/di-oxygenation is a novel pathway; and the genes related to CTAB biodegradation were associated with Pseudomonas spp. Four metabolites - palmitic acid, trimethylamine N-oxide (TMAO), myristic acid, and betaine - were the key identified biodegradation intermediates of CTAB, and they were associated with first-step mono-/di-oxygenations at the α/β-C. This tri-omics approach with CTAB demonstrates its power for identifying promising paths for future research on the biodegradation of complex organics by microbial communities., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Previous studies have identified that Geobacter sulfurreducens has three different electron transfer pathways for respiration, and it switches between these pathways to adapt to the redox potential of its electron acceptor. However, only a small fraction of the electron carriers from each pathway have been identified. In this study, we combined electrochemical and gene expression data to identify electron carriers in the inner membrane, periplasm, outer membrane, and exterior of the cell that may be induced by the use of the three different electron transfer pathways. Cyclic voltammetry was performed on thin biofilms grown on anodes poised at different redox potentials, providing a quantitative assessment of the relative use of three electron-transfer pathways in each condition (catalytic midpoint potentials (E KA s) of -0.227 V [Low], -0.15 V [Medium], -0.1 V [High] vs. SHE). Transcriptomic analyses as a function of electrochemical signals or fumarate utilization showed differential induction in inner membrane (Medium: cbcL), periplasmic (Low: ppcB/ppcE, Medium: ppcA), outer membrane (Low: extA/extC, Medium: extJ/extK, Fumarate: extF/extG), and extracellular (Medium: omcZ, High/Fumarate: omcS/omcT) cytochromes, suggesting the pathway signals are associated with complex transcriptomic responses in genes across the electron transfer pathway. Our method combining electrochemical modeling and transcriptomics could be adapted to better understand electron transport in other electroactive organisms with complex metabolisms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The gut microbiome is emerging as a key modulator of human energy balance. Prior studies in humans lacked the environmental and dietary controls and precision required to quantitatively evaluate the contributions of the gut microbiome. Using a Microbiome Enhancer Diet (MBD) designed to deliver more dietary substrates to the colon and therefore modulate the gut microbiome, we quantified microbial and host contributions to human energy balance in a controlled feeding study with a randomized crossover design in young, healthy, weight stable males and females (NCT02939703). In a metabolic ward where the environment was strictly controlled, we measured energy intake, energy expenditure, and energy output (fecal and urinary). The primary endpoint was the within-participant difference in host metabolizable energy between experimental conditions [Control, Western Diet (WD) vs. MBD]. The secondary endpoints were enteroendocrine hormones, hunger/satiety, and food intake. Here we show that, compared to the WD, the MBD leads to an additional 116 ± 56 kcals (P < 0.0001) lost in feces daily and thus, lower metabolizable energy for the host (89.5 ± 0.73%; range 84.2-96.1% on the MBD vs. 95.4 ± 0.21%; range 94.1-97.0% on the WD; P < 0.0001) without changes in energy expenditure, hunger/satiety or food intake (P > 0.05). Microbial 16S rRNA gene copy number (a surrogate of biomass) increases (P < 0.0001), beta-diversity changes (whole genome shotgun sequencing; P = 0.02), and fermentation products increase (P < 0.01) on an MBD as compared to a WD along with significant changes in the host enteroendocrine system (P < 0.0001). The substantial interindividual variability in metabolizable energy on the MBD is explained in part by fecal SCFAs and biomass. Our results reveal the complex host-diet-microbiome interplay that modulates energy balance., (© 2023. The Author(s).)

An emerging area of research extends work on couple functioning and physical health to gut health, a critical marker of general health and known to diminish with age. As a foray into this area, we conducted a pilot study to (1) determine the feasibility of remote data collection, including a fecal sample, from older adult couples, (2) examine within-couple concordance in gut microbiota composition, and (3) examine associations between relationship functioning and gut microbiota composition. Couples (N = 30) were recruited from the community. The participants' demographic characteristics were as follows: M (SD) age = 66.6 (4.8), 53% female, 92% White, and 2% Hispanic. Two of the couples were same-sex. All 60 participants completed self-report measures and supplied a fecal sample for microbiome analysis. Microbial DNA was extracted from the samples, and the 16S rRNA gene V4 region was amplified and sequenced. The results indicated that individuals shared more similar gut microbial composition with their partners than with others in the sample, p < 0.0001. In addition, individuals with better relationship quality (greater relationship satisfaction and intimacy and less avoidant communication) had greater microbial diversity, p < 0.05, a sign of healthier gut microbiota. Further research with a larger and more diverse sample is warranted to elucidate mechanisms.

Introduction: Aflatoxin B1 (AFB1) is a carcinogen produced by Aspergillus flavus and Aspergillus parasiticus which grow on maize. Given the high prevalence of child stunting (ie, impaired growth) and other nutritional disorders in low-income and middle-income countries, where maize is consumed, the role of aflatoxin exposure may be significant. Observational reports have demonstrated associations between aflatoxin exposure and impaired child growth; however, most have been cross-sectional and have not assessed seasonal variations in aflatoxin, food preparation and dynamic changes in growth. Biological mechanistic data on how aflatoxin may exert an impact on child growth is missing. This study incorporates a prospective cohort of children from rural Guatemala to assess (1) temporal associations between aflatoxin exposure and child growth and (2) possible mediation of the gut microbiome among aflatoxin exposure, inflammation and child growth., Methods and Analysis: We will prospectively evaluate aflatoxin exposure and height-for-age difference trajectories for 18 months in a cohort of 185 children aged 6-9 months at enrolment. We will assess aflatoxin exposure levels and biomarkers of gut and systemic inflammation. We will examine the faecal microbiome of each child and identify key species and metabolic pathways for differing AFB1 exposure levels and child growth trajectories. In parallel, we will use bioreactors, inoculated with faeces, to investigate the response of the gut microbiome to varying levels of AFB1 exposure. We will monitor key microbial metabolites and AFB1 biotransformation products to study nutrient metabolism and the impact of the gut microbiome on aflatoxin detoxification/metabolism. Finally, we will use path analysis to summarise the effect of aflatoxin exposure and the gut microbiome on child growth., Ethics and Dissemination: Ethics approval was obtained from Arizona State University Institutional Review Board (IRB; STUDY00016799) and Wuqu' Kawoq/Maya Health Alliance IRB (WK-2022-003). Findings will be disseminated in scientific presentations and peer-reviewed publications., Competing Interests: Competing interests: No, there are no competing interests., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Fe 0 is a powerful chemical reductant with applications for remediation of chlorinated solvents, including tetrachloroethene and trichloroethene. Its utilization efficiency at contaminated sites is limited because most of the electrons from Fe 0 are channeled to the reduction of water to H 2 rather than to the reduction of the contaminants. Coupling Fe 0 with H 2 -utilizing organohalide-respiring bacteria (i.e., Dehalococcoides mccartyi ) could enhance trichloroethene conversion to ethene while maximizing Fe 0 utilization efficiency. Columns packed with aquifer materials have been used to assess the efficacy of a treatment combining in space and time Fe 0 and a D. mccartyi -containing culture (bioaugmentation). To date, most column studies documented only partial conversion of the solvents to chlorinated byproducts, calling into question the feasibility of Fe 0 to promote complete microbial reductive dechlorination. In this study, we decoupled the application of Fe 0 in space and time from the addition of organic substrates and D. mccartyi -containing cultures. We used a column containing soil and Fe 0 (at 15 g L -1 in porewater) and fed it with groundwater as a proxy for an upstream Fe 0 injection zone dominated by abiotic reactions and biostimulated/bioaugmented soil columns (Bio-columns) as proxies for downstream microbiological zones. Results showed that Bio-columns receiving reduced groundwater from the Fe 0 -column supported microbial reductive dechlorination, yielding up to 98% trichloroethene conversion to ethene. The microbial community in the Bio-columns established with Fe 0 -reduced groundwater also sustained trichloroethene reduction to ethene (up to 100%) when challenged with aerobic groundwater. This study supports a conceptual model where decoupling the application of Fe 0 and biostimulation/bioaugmentation in space and/or time could augment microbial trichloroethene reductive dechlorination, particularly under oxic conditions.

Population-level nutritional assessments often rely on self-reported data, which increases the risk of recall bias. Here, we demonstrate that wastewater-based epidemiology can be used for near real-time population dietary assessments. Neighbourhood-level, untreated wastewater samples were collected monthly from within an urban population in the south-western United States from August 2017 to July 2019. Using liquid chromatography-tandem mass spectrometry, we identify recurring seasonal dynamics in phytoestrogen consumption, including dietary changes linked to the winter holiday season. Using 16S ribosomal RNA gene amplicon sequencing, we demonstrated the feasibility of detecting sewage-derived human gut bacterial taxa involved in phytoestrogen metabolism, including Bifidobacterium, Blautia and Romboutsia. Combined metabolomic and genomic wastewater analysis can inform nutritional assessments at population scale, indicating wastewater-based epidemiology as a promising tool for actionable and cost-effective data collection to support public health nutrition., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

We describe the technology and validation of a new whole room indirect calorimeter (WRIC) methodology to quantify volume of methane (VCH 4 ) released from the human body over 24 h concurrently with the assessment of energy expenditure and substrate utilization. The new system extends the assessment of energy metabolism by adding CH 4 , a downstream product of microbiome fermentation that could contribute to energy balance. Our new system consists of an established WRIC combined with the addition of off-axis integrated-cavity output spectroscopy (OA-ICOS) to measure CH 4 concentration ([CH 4 ]). Development, validation, and reliability of the system included environmental experiments to measure the stability of the atmospheric [CH 4 ], infusing CH 4 into the WRIC and human cross-validation studies comparing [CH 4 ] quantified by OA-ICOS and mid-infrared dual-comb spectroscopy (MIR DCS).Our infusion data indicated that the system measured 24-h [CH 4 ] and VCH 4 with high sensitivity, reliability, and validity. Cross-validation studies showed good agreement between OA-ICOS and MIR DCS technologies (r = 0.979, P < 0.0001). Human data revealed 24-h VCH 4 was highly variable between subjects and within/between days. Finally, our method to quantify VCH 4 released by breath or colon suggested that over 50% of the CH 4 was eliminated through the breath. The method allows, for the first time, measurement of 24-h VCH 4 (in kcal) and therefore the measurement of the proportion of human energy intake fermented to CH 4 by the gut microbiome and released via breath or from the intestine; also, it allows us to track the effects of dietary, probiotic, bacterial, and fecal microbiota transplantation on VCH 4 . NEW & NOTEWORTHY This is the first time that continuous assessment of CH 4 is reported in parallel with measurements of O 2 consumption and CO 2 production inside a whole room indirect calorimeter in humans and over 24 h. We provide a detailed description of the whole system and its parts. We carried out studies of reliability and validity of the whole system and its parts. CH 4 is released in humans during daily activities.

Geobacter sulfurreducens is a ubiquitous iron-reducing bacterium in soils, and in engineered systems, it can respire an electrode to produce measurable electric current. Its unique metabolism, heavily dependent on an extensive network of cytochromes, requires a unique cell composition. In this work, we used metallomics, cell fraction and elemental analyses, and transcriptomics to study and analyze the cell composition of G. sulfurreducens. Elemental composition studies (C, H, O, N, and ash content) showed high C:O and H:O ratios of approximately 1.7:1 and 0.25:1, indicative of more reduced cell composition that is consistent with high lipid content. Our study shows that G. sulfurreducens cells have a large amount of iron (2 ± 0.2 μg/g dry weight) and lipids (32 ± 0.5% dry weight/dry weight) and that this composition does not change whether the cells are grown with a soluble or an insoluble electron acceptor. The high iron concentration, higher than similar microorganisms, is attributed to the production of cytochromes that are abundant in transcriptomic analyses in both solid and soluble electron acceptor growth. The unique cell composition of G. sulfurreducens must be considered when growing this microorganism for lab studies and commercial applications. IMPORTANCE Geobacter sulfurreducens is an electroactive microorganism. In nature, it grows on metallic minerals by transferring electrons to them, effectively "breathing" metals. In a manmade system, it respires an electrode to produce an electric current. It has become a model organism for the study of electroactive organisms. There are potential biotechnological applications of an organism that can bridge the gap between biology and electrical signal and, as a ubiquitous iron reducer in soils around the world, G. sulfurreducens has an impact on the global iron cycle. We measured the concentrations of metals, macromolecules, and basic elements in G. sulfurreducens to define this organism's composition. We also used gene expression data to discuss which proteins those metals could be associated with. We found that G. sulfurreducens has a large amount of lipid and iron compared to other bacteria-these observations are important for future microbiologists and biotechnologists working with the organism.

Links between gut microbiota and autism spectrum disorder (ASD) have been explored in many studies using 16S rRNA gene amplicon and shotgun sequencing. Based on these links, microbiome therapies have been proposed to improve gastrointestinal (GI) and ASD symptoms in ASD individuals. Previously, our open-label microbiota transfer therapy (MTT) study provided insight into the changes in the gut microbial community of children with ASD after MTT and showed significant and long-term improvement in ASD and GI symptoms. Using samples from the same study, the objective of this work was to perform a deeper taxonomic and functional analysis applying shotgun metagenomic sequencing. Taxonomic analyses revealed that ASD Baseline had many bacteria at lower relative abundances, and their abundance increased after MTT. The relative abundance of fiber consuming and beneficial microbes including Prevotella ( P. dentalis , P. enoeca , P. oris , P. meloninogenica ), Bifidobacterium bifidum , and a sulfur reducer Desulfovibrio piger increased after MTT-10wks in children with ASD compared to Baseline (consistent at genus level with the previous 16S rRNA gene study). Metabolic pathway analysis at Baseline compared to typically developing (TD) children found an altered abundance of many functional genes but, after MTT, they became similar to TD or donors. Important functional genes that changed included: genes encoding enzymes involved in folate biosynthesis, sulfur metabolism and oxidative stress. These results show that MTT treatment not only changed the relative abundance of important genes involved in metabolic pathways, but also seemed to bring them to a similar level to the TD controls. However, at a two-year follow-up, the microbiota and microbial genes shifted into a new state, distinct from their levels at Baseline and distinct from the TD group. Our current findings suggest that microbes from MTT lead to initial improvement in the metabolic profile of children with ASD, and major additional changes at two years post-treatment. In the future, larger cohort studies, mechanistic in vitro experiments and metatranscriptomics studies are recommended to better understand the role of these specific microbes, functional gene expression, and metabolites relevant to ASD.

Hydrogen (H 2 ) is a crucial electron donor for many processes in the environment including nitrate-, sulfate- and, iron-reduction, homoacetogenesis, and methanogenesis, and is a major determinant of microbial competition and metabolic pathways in groundwater, sediments, and soils. Despite the importance of H 2 for many microbial processes in the environment, the total H 2 consuming capacity (or H 2 demand) of soils is generally unknown. Using soil microcosms with added H 2 , the aims of this study were 1) to measure the H 2 demand of geochemically diverse soils and 2) to define the processes leading to this demand. Study results documented a large range of H 2 demand in soil (0.034-1.2 millielectron equivalents H 2 g -1 soil). The measured H 2 demand greatly exceeded the theoretical demand predicted based on measured concentrations of common electron acceptors initially present in a library of 15 soils. While methanogenesis accounted for the largest fraction of H 2 demand, humic acid reduction and acetogenesis were also significant contributing H 2 -consuming processes. Much of the H 2 demand could be attributed to CO 2 produced during incubation from fermentation and/or acetoclastic methanogenesis. The soil initial total organic carbon showed the strongest correlation to H 2 demand. Besides external additions, H 2 was likely generated or cycled in the microcosms. Apart from fermentative H 2 production, carboxylate elongation to produce C4-C7 fatty acids may have accounted for additional H 2 production in these soils. Many of these processes, especially the organic carbon contribution is underestimated in microbial models for H 2 consumption in natural soil ecosystems or during bioremediation of contaminants in soils., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Field-weathered crude oil-containing soils have a residual concentration of hydrocarbons with complex chemical structure, low solubility, and high viscosity, often poorly amenable to microbial degradation. Hydrogen peroxide (H 2 O 2 )-based oxidation can generate oxygenated compounds that are smaller and/or more soluble and thus increase petroleum hydrocarbon biodegradability. In this study, we assessed the efficacy of H 2 O 2 -based oxidation under unsaturated soil conditions to promote biodegradation in a field-contaminated and weathered soil containing high concentrations of total petroleum hydrocarbons (25200 mg TPH kg -1 ) and total organic carbon (80900 mg TOC kg -1 ). Microcosms amended with three doses of 48 g H 2 O 2 kg -1 soil (unactivated or Fe 2+ -activated) or 24 g sodium percarbonate kg -1 soil and nutrients did not show substantial TPH changes during the experiment. However, 7.6-41.8% of the TOC concentration was removed. Furthermore, production of DOC was enhanced and highest in the microcosms with oxidants, with approximately 20-40-fold DOC increase by the end of incubation. In the absence of oxidants, biostimulation led to > 50% TPH removal in 42 days. Oxidants limited TPH biodegradation by diminishing the viable concentration of microorganisms, altering the composition of the soil microbial communities, and/or creating inhibitory conditions in soil. Study's findings underscore the importance of soil characteristics and petroleum hydrocarbon properties and inform on potential limitations of combined H 2 O 2 oxidation and biodegradation in weathered soils., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Microbial communities mediate the transformation of organic matter within landfills into methane (CH 4 ). Yet their ecological role in CH 4 production is rarely evaluated. To characterize the microbiome associated with this biotransformation, the overall community and methanogenic Archaea were surveyed in an arid landfill using leachate collected from distinctly aged landfill cells (i.e., younger, intermediate, and older). We hypothesized that distinct methanogenic niches exist within an arid landfill, driven by geochemical gradients that developed under extended and age-dependent waste biodegradation stages. Using 16S rRNA and mcrA gene amplicon sequencing, we identified putative methanogenic niches as follows. The order Methanomicrobiales was the most abundant order in leachate from younger cells, where leachate temperature and propionate concentrations were measured at 41.8°C ± 1.7°C and 57.1 ± 10.7 mg L -1 . In intermediate-aged cells, the family Methanocellaceae was identified as a putative specialist family under intermediate-temperature and -total dissolved solid (TDS) conditions, wherein samples had a higher alpha diversity index and near CH 4 concentrations. In older-aged cells, accumulating metals and TDS supported Methanocorpusculaceae , " Candidatus Bathyarchaeota," and " Candidatus Verstraetearchaeota" operational taxonomic units (OTUs). Consistent with the mcrA data, we assayed methanogenic activity across the age gradient through stable isotopic measurements of δ 13 C of CH 4 and δ 13 C of CO 2 . The majority (80%) of the samples' carbon fractionation was consistent with hydrogenotrophic methanogenesis. Together, we report age-dependent geochemical gradients detected through leachate in an arid landfill seemingly influencing CH 4 production, niche partitioning, and methanogenic activity. IMPORTANCE Microbiome analysis is becoming common in select municipal and service ecosystems, including wastewater treatment and anaerobic digestion, but its potential as a microbial-status-informative tool to promote or mitigate CH 4 production has not yet been evaluated in landfills. Methanogenesis mediated by Archaea is highly active in solid-waste microbiomes but is commonly neglected in studies employing next-generation sequencing techniques. Identifying methanogenic niches within a landfill offers detail into operations that positively or negatively impact the commercial production of methane known as biomethanation. We provide evidence that the geochemistry of leachate and its microbiome can be a variable accounting for ecosystem-level (coarse) variation of CH 4 production, where we demonstrate through independent assessments of leachate and gas collection that the functional variability of an arid landfill is linked to the composition of methanogenic Archaea .

Alterations to the gut microbiome have been reported between children with autism spectrum disorders (ASDs) and typically developing (TD) children. Characterizing these differences has led to the proposal of new treatments for ASD, such as probiotic interventions and fecal matter transplants. However, no study to date has characterized the gut microbiome or metabolome in Pitt Hopkins syndrome (PTHS), a severe ASD with a high incidence of gastrointestinal (GI) disturbances such as constipation. Here, we surveyed the gut microbiome and metabolome in a cohort of PTHS individuals and their unaffected parents. We focused our analysis on Clostridium bolteae, a microbe previously associated with ASD known to chemically modify bile acids in the gut. PTHS individuals carry a higher load of C. bolteae than their parents as well as both ASD and non-ASD individuals from the American Gut Project cohort. Specific metabolites were associated with PTHS, including bile acids and sphingosines. With a metadata reanalysis tool, we found that PTHS-associated metabolites have previously been identified in inflammatory bowel disease and obesity patients. These results suggest microbial involvement in PTHS, but further research must be performed to clarify the exact mechanisms through which microbes may act. Furthermore, new associations between PTHS-specific metabolites and other conditions may lead to additional therapeutic options for PTHS individuals. IMPORTANCE GI disturbances in ASD such as severe constipation can be medically significant and often require medication. This is especially true for individuals with PTHS, suggesting that the gut microbiome may be involved in PTHS's pathology. Revealing associations between specific gut microbes and PTHS may allow the development of new therapeutics or the application of existing therapeutics to ease day-to-day challenges encountered by PTHS individuals. In this study, we characterized an association between C. bolteae and PTHS, in addition to metabolites linked to both PTHS and C. bolteae . We also identified other microbiome-involved medical conditions where PTHS-associated metabolites have been isolated. Utilizing common metabolites to identify conditions with similar phenotypes may suggest new therapeutic options for GI-related symptoms.

Menopause in human females and subsequent ovarian hormone deficiency, particularly concerning 17β-estradiol (E2), increase the risk for metabolic dysfunctions associated with obesity, diabetes type 2, cardiovascular diseases, and dementia. Several studies indicate that these disorders are also strongly associated with compositional changes in the intestinal microbiota; however, how E2 deficiency and hormone therapy affect the gut microbial community is not well understood. Using a rat model, we aimed to evaluate how ovariectomy (OVX) and subsequent E2 administration drive changes in metabolic health and the gut microbial community, as well as potential associations with learning and memory. Findings indicated that OVX-induced ovarian hormone deficiency and E2 treatment had significant impacts on several health-affecting parameters, including (a) the abundance of some intestinal bacterial taxa (e.g., Bifidobacteriaceae and Porphyromonadaceae ), (b) the abundance of microbial short-chain fatty acids (SCFAs) (e.g., isobutyrate), (c) weight/BMI, and (d) high-demand spatial working memory following surgical menopause. Furthermore, exploratory correlations among intestinal bacteria abundance, cognition, and BMI underscored the putative influence of surgical menopause and E2 administration on gut-brain interactions. Collectively, this study showed that surgical menopause is associated with physiological and behavioral changes, and that E2-linked compositional changes in the intestinal microbiota might contribute to some of its related negative health consequences. Overall, this study provides novel insights into interactions among endocrine and gastrointestinal systems in the post-menopausal life stage that collectively alter the risk for the development and progression of cardiovascular, metabolic, and dementia-related diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zeibich, Koebele, Bernaud, Ilhan, Dirks, Northup-Smith, Neeley, Maldonado, Nirmalkar, Files, Mayer, Bimonte-Nelson and Krajmalnik-Brown.)

Background: Overweight, obesity, and associated comorbidities are a pressing global issue among children of all ages, particularly among low-income populations. Rapid weight gain (RWG) in the first 6 months of infancy contributes to childhood obesity. Suboptimal sleep-wake patterns and gut microbiota (GM) have also been associated with childhood obesity, but little is known about their influences on early infant RWG. Sleep may alter the GM and infant metabolism, and ultimately impact obesity; however, data on the interaction between sleep-wake patterns and GM development on infant growth are scarce. In this study, we aim to investigate associations of infant sleep-wake patterns and GM development with RWG at 6 months and weight gain at 12 months. We also aim to evaluate whether temporal interactions exist between infant sleep-wake patterns and GM, and if these relations influence RWG., Methods: The Snuggle Bug/ Acurrucadito study is an observational, longitudinal study investigating whether 24-h, actigraphy-assessed, sleep-wake patterns and GM development are associated with RWG among infants in their first year. Based on the Ecological Model of Growth, we propose a novel conceptual framework to incorporate sleep-wake patterns and the GM as metabolic contributors for RWG in the context of maternal-infant interactions, and familial and socio-physical environments. In total, 192 mother-infant pairs will be recruited, and sleep-wake patterns and GM development assessed at 3 and 8 weeks, and 3, 6, 9, and 12 months postpartum. Covariates including maternal and child characteristics, family and environmental factors, feeding practices and dietary intake of infants and mothers, and stool-derived metabolome and exfoliome data will be assessed. The study will apply machine learning techniques combined with logistic time-varying effect models to capture infant growth and aid in elucidating the dynamic associations between study variables and RWG., Discussion: Repeated, valid, and objective assessment at clinically and developmentally meaningful intervals will provide robust measures of longitudinal sleep, GM, and growth. Project findings will provide evidence for future interventions to prevent RWG in infancy and subsequent obesity. The work also may spur the development of evidence-based guidelines to address modifiable factors that influence sleep-wake and GM development and prevent childhood obesity., (© 2021. The Author(s).)

There is an increased interest in finding remedies for contamination in low permeability and advection-limited aquifers. A technology applicable at these sites, electrokinetic-enhanced bioremediation (EK-BIO), combines traditional bioremediation and electrokinetic technologies by applying direct current to transport bioremediation amendments and microbes in situ. The effect of this technology on the native soil microbial community has only been previously investigated at the bench scale. This research explored the influence of EK-BIO on subsurface microbial communities at a field-scale demonstration site. The results showed that, similar to the findings in laboratory studies, alpha diversity decreased and beta diversity differed temporally, based on treatment phase. Enrichments in specific taxa were linked to the bioaugmentation culture and electron donor. Overall, findings from our study, one of the first field-scale investigations of the influence of electrokinetic bioremediation on subsurface microbial communities, are very similar to bench-scale studies on the topic, suggesting good correlation between laboratory and field experiments on EK-BIO and showing that lessons learned at the benchtop are important and relevant to field-scale implementation. KEY POINTS: • Microbial community analysis of field samples validates laboratory study results • Bioaugmentation cultures and electron donors have largest effect on microbial community., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: The large intestine provides a compensatory role in energy recovery when surgical interventions such as extensive small intestinal resections or bypass operations lower the efficiency of nutrient absorption in the upper gastrointestinal (GI) tract. While microorganisms in the colon are known to play vital roles in recovering energy, their contributions remain to be qualified and quantified in the small intestine resection., Objective: We develop a mathematical model that links nutrient absorption in the upper and lower GI tract in two steps., Methods: First, we describe the effects of small intestine resection on the ileocecal output (ICO), which enters the colon and provides food for microbes. Second, we describe energy recovered by the colon's microorganisms via short-chain fatty acid (SCFA) production. We obtain model parameters by performing a least-squares regression analysis on clinical data for subjects with normal physiology and those who had undergone small intestine resection., Results: For subjects with their intestines intact, our model provided a metabolizable energy value that aligns well with the traditional Atwater coefficients. With removal of the small intestine, physiological absorption became less efficient, and the metabolizable energy decreased. In parallel, the inefficiencies in physiological absorption by the small intestine are partly compensated by production of short-chain fatty acids (SCFA) from proteins and carbohydrates by microorganisms in the colon. The colon recovered more than half of the gross energy intake when the entire small intestine was removed. Meanwhile, the quality of energy absorbed changed, because microbe-derived SCFAs, not the original components of food, become the dominant form of absorbed energy., Conclusion: The mathematical model developed here provides an important framework for describing the effect of clinical interventions on the colon's microorganisms., Competing Interests: The authors have declared that no competing interests exist.

Chromium (Cr) (VI) is a toxic, mutagenic, and carcinogenic water pollutant. The standard ion chromatography (IC) method for quantification of Cr (VI) in water samples is Environmental Protection Agency Method 218.7, which requires postcolumn derivatization with 1,5-diphenylcarbazide and UV-Vis spectroscopy detection. Method 218.7 is Cr (VI) specific; thus, it does not allow detection of co-occurring natural and anthropogenic anions in environmental media. In this study, we developed an isocratic IC method with suppressed conductivity detection, a Metrohm Metrosep A Supp 7 column, and sodium carbonate/acetonitrile as mobile phase for simultaneous quantification of Cr (VI), C l O 4 - , As (V) as arsenate, Se (VI) as selenate, and the common anions F - , Cl - , N O 2 - , N O 3 - , and S O 4 2 - . The determination coefficient for every analyte was >0.99 and the method showed good accuracy in quantification. Cr (VI), As (V), Se (VI), and C l O 4 - limit of detection and limit of quantification were 0.1-0.6 μg/L and 0.5-2.1 μg/L, respectively. Recovery of Cr (VI) in various aqueous samples (tap water, surface water, groundwater, and wastewater) was between 97.2% and 102.8%. Overall, most analytes showed acceptable recovery (80-120%) in the environmental samples tested. The IC method was applied to track Cr (VI) and other anion concentrations in laboratory batch microcosms experiments with soil, surface water, and anaerobic medium. The IC method developed in this study should prove useful to environmental practitioners, academic and research organizations, and industries for monitoring low concentrations of multiple anions in environmental media, helping to decrease the sample requirement, time, and cost of analysis., Competing Interests: No competing financial interests exist., (© Srivatsan Mohana Rangan et al. 2021; Published by Mary Ann Liebert, Inc.)

Microbiological conversion of CO 2 into biofuels and/or organic industrial feedstock is an excellent carbon-cycling strategy. Here, autotrophic anaerobic bacteria in the membrane biofilm reactor (MBfR) transferred electrons from hydrogen gas (H 2 ) to inorganic carbon (IC) and produced organic acids and alcohols. We systematically varied the H 2 -delivery, the IC concentration, and the hydraulic retention time in the MBfR. The relative availability of H 2 versus IC was the determining factor for enabling microbial chain elongation (MCE). When the H 2 :IC mole ratio was high (>2.0 mol H 2 /mol C), MCE was an important process, generating medium-chain carboxylates up to octanoate (C8, 9.1 ± 1.3 mM C and 28.1 ± 4.1 mmol C m -2  d -1 ). Conversely, products with two carbons were the only ones present when the H 2 :IC ratio was low (<2.0 mol H 2 /mol C), so that H 2 was the limiting factor. The biofilm microbial community was enriched in phylotypes most similar to the well-known acetogen Acetobacterium for all conditions tested, but phylotypes closely related with families capable of MCE (e.g., Bacteroidales, Rhodocyclaceae, Alcaligenaceae, Thermoanaerobacteriales, and Erysipelotrichaceae) became important when the H 2 :IC ratio was high. Thus, proper management of IC availability and H 2 supply allowed control over community structure and function, reflected by the chain length of the carboxylates and alcohols produced in the MBfR., (© 2021 Wiley Periodicals LLC.)

Background: Polyphenols are secondary metabolites produced by plants to defend themselves from environmental stressors. We explored the effect of Wolffia globosa 'Mankai', a novel cultivated strain of a polyphenol-rich aquatic plant, on the metabolomic-gut clinical axis in vitro, in-vivo and in a clinical trial., Methods: We used mass-spectrometry-based metabolomics methods from three laboratories to detect Mankai phenolic metabolites and examined predicted functional pathways in a Mankai artificial-gut bioreactor. Plasma and urine polyphenols were assessed among the 294 DIRECT-PLUS 18-month trial participants, comparing the effect of a polyphenol-rich green-Mediterranean diet (+1240 mg/polyphenols/day, provided by Mankai, green tea and walnuts) to a walnuts-enriched (+440 mg/polyphenols/day) Mediterranean diet and a healthy controlled diet., Results: Approximately 200 different phenolic compounds were specifically detected in the Mankai plant. The Mankai-supplemented bioreactor artificial gut displayed a significantly higher relative-abundance of 16S-rRNA bacterial gene sequences encoding for enzymes involved in phenolic compound degradation. In humans, several Mankai-related plasma and urine polyphenols were differentially elevated in the green Mediterranean group compared with the other groups ( p < 0.05) after six and 18 months of intervention (e.g., urine hydroxy-phenyl-acetic-acid and urolithin-A; plasma Naringenin and 2,5-diOH-benzoic-acid). Specific polyphenols, such as urolithin-A and 4-ethylphenol, were directly involved with clinical weight-related changes., Conclusions: The Mankai new plant is rich in various unique potent polyphenols, potentially affecting the metabolomic-gut-clinical axis.

Groundwater co-contaminated with 1,4-dioxane, 1,1,1-trichloroethane (TCA), and trichloroethene (TCE) is among the most urgent environmental concerns of the U.S. Department of Defense (DoD), U.S. Environmental Protection Agency (EPA), and industries related to chlorinated solvents. Inspired by the pressing need to remove all three contaminants at many sites, we tested a synergistic platform: catalytic reduction of 1,1,1-TCA and TCE to ethane in a H 2 -based membrane palladium-film reactor (H 2 -MPfR), followed by aerobic biodegradation of ethane and 1,4-dioxane in an O 2 -based membrane biofilm reactor (O 2 -MBfR). During 130 days of continuous operation, 1,1,1-TCA and TCE were 95-98% reductively dechlorinated to ethane in the H 2 -MPfR, and ethane served as the endogenous primary electron donor for promoting 98.5% aerobic biodegradation of 1,4-dioxane in the O 2 -MBfR. In addition, the small concentrations of the chlorinated intermediate from the H 2 -MPfR, dichloroethane (DCA) and monochloroethane (MCA), were fully biodegraded through aerobic biodegradation in the O 2 -MBfR. The biofilms in the O 2 -MBfR were enriched in phylotypes closely related to the genera Pseudonocardia known to biodegrade 1,4-dioxane.

Quaternary ammonium compounds (QAC, e.g., cetyltrimethylammonium bromide, (CTAB)) are widely used as surfactants and disinfectants. QAC already are commonly found in wastewaters, and their concentration could increase, since QAC are recommended to inactivate the SARS-CoV-2 (COVID-19) virus. Exposure of bacteria to QAC can lead to proliferation of antibiotic resistance genes (ARG). In particular, O 2 -based membrane biofilm reactors (O 2 -MBfRs) achieved excellent CTAB biodegradation, but ARG increased in their biofilms. Here, we applied meta-transcriptomic analyses to assess the impacts of CTAB exposure and operating conditions on microbial community's composition and ARG expression in the O 2 -MBfRs. Two opportunistic pathogens, Pseudomonas aeruginosa and Stenotrophomonas maltophilia, dominated the microbial communities and were associated with the presence of ARG. Operating conditions that imposed stress on the biofilms, i.e., limited supplies of O 2 and nitrogen or a high loading of CTAB, led to large increases in ARG expression, particularly for genes conferring antibiotic-target protection. Important within the efflux pumps was the Resistance-Nodulation-Division (RND) family, which may have been active in exporting CTAB from cells. Oxidative stress appeared to be the key factor that triggered ARG proliferation by selecting intrinsically resistant species and accentuating the expression of ARG. Our findings suggest that means to mitigate the spread of ARG, such as shown here in a O 2 -based membrane biofilm reactor, need to consider the impacts of stressors, including QAC exposure and stressful operating conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Research relating gut microbiome composition to autism spectrum disorders (ASD) has produced inconsistent results, indicative of the disorder's complexity and the need for more sophisticated experimental designs. We address this need by (i) comparing gut microbiome composition between individuals with ASD and neurotypical controls in Arizona and Colorado using standardized DNA extraction and sequencing methods at both locations and (ii) longitudinally evaluating the gut microbiome's relationship to autism behavioral severity, diet, and gastrointestinal symptoms. Gut microbiome composition differed between individuals in Arizona and individuals in Colorado, and gastrointestinal symptoms were significantly higher in ASD individuals than in neurotypical individuals in Arizona but not in Colorado. Gut microbiome composition was significantly associated with ASD while controlling for study-site location but not when controlling for gastrointestinal symptoms. This suggests that non-ASD-related study site differences in gut microbiome composition and different degrees of gastrointestinal symptoms involvement with ASD between sites may contribute to inconsistent results in the literature regarding the association between gut microbiome composition and ASD. In the longitudinal analysis, we found that difference in levels of lethargy/social withdrawal measured in individuals at different time points correlated with the degree of change in gut microbiome composition and that a worsening of inappropriate speech between time points was associated with decreased gut microbiome diversity. This relationship between changes in the gut microbiome composition within individuals and ASD behavioral severity metrics indicates that longitudinal study designs may be useful for exploring microbial drivers of ASD severity when substantial variability exists in baseline microbiome compositions across individuals and geographical regions. IMPORTANCE Autism spectrum disorder (ASD) is a brain developmental disorder with varying behavioral symptom severity both across individuals and within individuals over time. There have been promising but also inconsistent literature results regarding how the gut microbiota (microbiome) may be involved. We found that the gut microbiome in individuals with ASD is affected by study-site location as well as gastrointestinal symptom severity. When we sampled some individuals with ASD at several different time points, we found that some behaviors, such as lethargy/social withdrawal and inappropriate speech, changed along with changes in the gut microbiota composition. This is the first study to relate severity of behavior symptoms to gut microbiome composition within individuals over time and suggests a dynamic relationship between ASD-associated symptoms and gut microbes. Longitudinal study designs as well as collaborative efforts across multiple centers are needed to fully characterize the relationship between ASD and gut microbes., (Copyright © 2021 Fouquier et al.)

1,1,1-Trichloroethane (1,1,1-TCA) and trichloroethene (TCE) are common recalcitrant contaminants that coexist in groundwater. H 2 -induced reduction over precious-metal catalysts has proven advantageous, but its application to long-term continuous treatment has been limited due to poor H 2 -transfer efficiency and catalyst loss. Furthermore, catalytic reductions of aqueous 1,1,1-TCA alone or concomitant with TCE catalytic co-reductions are unstudied. Here, we investigated 1,1,1-TCA and TCE co-reduction using palladium nanoparticle (PdNP) catalysts spontaneously deposited on H 2 -transfer membranes that allow efficient H 2 supply on demand in a bubble-free form. The catalytic activities for 1,1,1-TCA and TCE reductions reached 9.9 and 11 L/g-Pd/min, values significantly greater than that reported for other immobilized-PdNP systems. During 90 day continuous operation, removals were up to 95% for 1,1,1-TCA and 99% for TCE. The highest steady-state removal fluxes were 1.5 g/m 2 /day for 1,1,1-TCA and 1.7 g/m 2 /day for TCE. The major product was nontoxic ethane (94% selectivity). Only 4% of the originally deposited PdNPs were lost over 90 days of continuous operation. Documenting long-term continuous Pd-catalyzed dechlorination at high surface loading with minimal loss of the catalyst mass or activity, this work expands understanding of and provides a foundation for sustainable catalytic removal of co-existing chlorinated solvents.

Background: Human and microbial metabolism are distinct disciplines. Terminology, metrics, and methodologies have been developed separately. Therefore, combining the 2 fields to study energetic processes simultaneously is difficult., Objectives: When developing a mechanistic framework describing gut microbiome and human metabolism interactions, energy values of food and digestive materials that use consistent and compatible metrics are required. As an initial step toward this goal, we developed and validated a model to convert between chemical oxygen demand (COD) and gross energy (${E&#95;g}$) for >100 food items and ingredients., Methods: We developed linear regression models to relate (and be able to convert between) theoretical gross energy (${E&#95;g}^{\prime}$) and chemical oxygen demand (COD'); the latter is a measure of electron equivalents in the food's carbon. We developed an overall regression model for the food items as a whole and separate regression models for the carbohydrate, protein, and fat components. The models were validated using a sample set of computed ${E&#95;g}^{\prime}$ and COD' values, an experimental sample set using measured ${E&#95;g}$ and COD values, and robust statistical methods., Results: The overall linear regression model and the carbohydrate, protein, and fat regression models accurately converted between COD and ${E&#95;g}$, and the component models had smaller error. Because the ratios of COD per gram dry weight were greatest for fats and smallest for carbohydrates, foods with a high fat content also had higher ${E&#95;g}$ values in terms of kcal · g dry weight-1., Conclusion: Our models make it possible to analyze human and microbial energetic processes in concert using a single unit of measure, which fills an important need in the food-nutrition-metabolism-microbiome field. In addition, measuring COD and using the regressions to calculate ${E&#95;g}$ can be used instead of measuring ${E&#95;g}$ directly using bomb calorimetry, which saves time and money., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society for Nutrition.)

Trichloroethene (TCE) and perchlorate (ClO 4 - ) are cocontaminants at multiple Superfund sites. Fe 0 is often used during TCE bioremediation with Dehalococcoides mccartyi to establish anoxic conditions in the aquifer. However, the synergy between Fe 0 abiotic reactions and microbiological TCE and ClO 4 - reductions is poorly understood and seldom addressed in the literature. Here, we investigated the effects of Fe 0 and its oxidation product, Fe 2 + , at field-relevant concentrations in promoting microbial TCE and ClO 4 - reductions. Using semibatch microcosms with a Superfund site soil and groundwater, we showed that the high Fe 0 concentration (16.5 g L -1 ) expected during Fe 0 in situ injection mostly yielded TCE abiotic reduction to ethene/ethane. However, such concentrations obscured dechlorination by D. mccartyi , impeded ClO 4 - reduction, and enhanced SO 4 2- reduction and methanogenesis. Fe 2 + at 0.25 g L -1 substantially delayed conversion of TCE to ethene when compared to no-Fe controls. A low concentration of aged-Fe 0 synergistically promoted microbiological TCE dechlorination to ethene while achieving complete ClO 4 - reduction. Collectively, these results illustrate scenarios relevant at or downstream of Fe 0 injection zones when Fe 0 is used to facilitate microbial dechlorination. Results also underscore the potential detrimental effects of Fe 0 and bioaugmentation cultures coinjection for in situ treatment of chlorinated ethenes and ClO 4 - .

Accumulating evidence has strengthened a link between dysbiotic gut microbiota and autism. Fecal microbiota transplant (FMT) is a promising therapy to repair dysbiotic gut microbiota. We previously performed intensive FMT called microbiota transfer therapy (MTT) for children with autism spectrum disorders (ASD) and observed a substantial improvement of gastrointestinal and behavioral symptoms. We also reported modulation of the gut microbiome toward a healthy one. In this study, we report comprehensive metabolite profiles from plasma and fecal samples of the children who participated in the MTT trial. With 619 plasma metabolites detected, we found that the autism group had distinctive metabolic profiles at baseline. Eight metabolites (nicotinamide riboside, IMP, iminodiacetate, methylsuccinate, galactonate, valylglycine, sarcosine, and leucylglycine) were significantly lower in the ASD group at baseline, while caprylate and heptanoate were significantly higher in the ASD group. MTT drove global shifts in plasma profiles across various metabolic features, including nicotinate/nicotinamide and purine metabolism. In contrast, for 669 fecal metabolites detected, when correcting for multiple hypotheses, no metabolite was significantly different at baseline. Although not statistically significant, p -cresol sulfate was relatively higher in the ASD group at baseline, and after MTT, the levels decreased and were similar to levels in typically developing (TD) controls. p -Cresol sulfate levels were inversely correlated with Desulfovibrio , suggesting a potential role of Desulfovibrio on p -cresol sulfate modulation. Further studies of metabolites in a larger ASD cohort, before and after MTT, are warranted, as well as clinical trials of other therapies to address the metabolic changes which MTT was not able to correct. IMPORTANCE Despite the prevalence of autism and its extensive impact on our society, no U.S. Food and Drug Administration-approved treatment is available for this complex neurobiological disorder. Based on mounting evidences that support a link between autism and the gut microbiome, we previously performed a pioneering open-label clinical trial using intensive fecal microbiota transplant. The therapy significantly improved gastrointestinal and behavioral symptoms. Comprehensive metabolomic measurements in this study showed that children with autism spectrum disorder (ASD) had different levels of many plasma metabolites at baseline compared to those in typically developing children. Microbiota transfer therapy (MTT) had a systemic effect, resulting in substantial changes in plasma metabolites, driving a number of metabolites to be more similar to those from typically developing children. Our results provide evidence that changes in metabolites are one mechanism of the gut-brain connection mediated by the gut microbiota and offer plausible clinical evidence for a promising autism treatment and biomarkers., (Copyright © 2020 Kang et al.)