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• Anammox adaptation to ambient temperature was linked to energy conservation strategy. • Expression patterns of cold shock proteins caused advantage of Ca' B. fulgida. • Overexpressed structural flexible core enzymes enhanced adaptability of Ca' B. fulgida. • Cross-feedings of amino acids and glycine betaine benefited their acclimation. Widespread application of anammox process has been primarily limited to the high sensitivity of anammox consortia to fluctuations of temperature. However, the metabolic acclimation of anammox consortia to decreased temperature remains unclear, which is the core of developing potential strategies for improving their low-temperature resistance. Here, we operated anammox reactors at 25 °C and 35 °C to explore the acclimation mechanism of anammox consortia in terms of metabolic responses and cross-feedings. Accordingly, we found that the adaptation of anammox consortia to ambient temperature (25 °C) was significantly linked to energy conservation strategy, resulting in decreased extracellular polymeric substance secretion, accumulation of ATP and amino acids. The expression patterns of cold shock proteins and core enzymes caused the apparent metabolic advantage of Candidatus Brocadia fulgida for acclimation to ambient temperature compared to other anammox species. Importantly, strengthened cross-feedings of amino acids, nitrite and glycine betaine benefited adaptation of anammox consortia to ambient temperature. Our work not only uncovers the temperature-adaptive mechanisms of anammox consortia, but also emphasizes the important role of metabolic cross-feeding in the temperature adaptation of microbial community. [ABSTRACT FROM AUTHOR]

The impact of commensal bacteria on the host arises from complex microbial-diet-host interactions. Mapping metabolic interactions in gut microbial communities is therefore key to understand how the microbiome influences the host. Here we use an interdisciplinary approach including isotope-resolved metabolomics to show that in Drosophila melanogaster, Acetobacter pomorum (Ap) and Lactobacillus plantarum (Lp) a syntrophic relationship is established to overcome detrimental host diets and identify Ap as the bacterium altering the host's feeding decisions. Specifically, we show that Ap uses the lactate produced by Lp to supply amino acids that are essential to Lp, allowing it to grow in imbalanced diets. Lactate is also necessary and sufficient for Ap to alter the fly's protein appetite. Our data show that gut bacterial communities use metabolic interactions to become resilient to detrimental host diets. These interactions also ensure the constant flow of metabolites used by the microbiome to alter reproduction and host behaviour. In the fly Drosophila melanogaster commensal bacteria and dietary essential amino acids control food choice behavior. Here, by using chemically defined diets and metabolomics, the authors show that Acetobacter pomorum (Ap) and Lactobacilli plantarum (Lp) engage in a mutualistic metabolic relationship to overcome detrimental diets, and identify Ap as the bacterium altering the host's feeding decisions. [ABSTRACT FROM AUTHOR]

• MAC-based MBBR preferentially consumed refractory organics of CPW. • Limited-oxygen created two-phase electrochemical systems on biofilm & sludge. • Fe redox cycle drove electroactive biofilms and then the suspended biomass. • The syntrophism of Geobacter & Syntrophorhabdus determined MAC biofilm superiority. • Ignavibacterium and Acidovorax might be novel partners for Fe redox cycle. To investigate the role of electroactive biofilms for enhanced phenolic degradation, lignite activated coke (LAC) and MAC were used as carriers in moving-bed biofilm reactor (MBBR) for CPW treatment. In contrast to activated sludge (AS) reactor, the carriers improved degradation performance of MBBR. Although two MBBRs exerted similar degradation capacity with over 92% of COD and 93% phenols removal under the highest phenolics concentration (500 mg/L), the effluent of MAC-based MBBR remained higher biodegradability (BOD 5 /COD = 0.34 vs 0.18) than that of LAC-based MBBR. Metagenomic analysis revealed that electroactive biofilms determined phenolic degradation of MAC-based MBBR. Primarily, Geobacter (17.33%) started Fe redox cycle on biofilms and developed syntrophy with Syntrophorhabdus (6.47%), which fermented phenols into easily biodegradable substrates. Subsequently, Ignavibacterium (3.38% to 2.52%) and Acidovorax (0.46% to 8.83%) conducted biological electricity from electroactive biofilms to suspended sludge. They synergized with dominated genus in suspended sludge, Alicycliphilus (19.56%) that accounted for phenolic oxidation and nitrate reduction. Consequently, the significantly advantage of Geobater and Syntrophorhabdus was the keystone reason for superior biodegradability maintenance of MAC-based MBBR. [ABSTRACT FROM AUTHOR]

• Xylan is a widely available carbohydrate with prebiotic potential. • Among five Bifidobacterium species, none could grow on xylan in pure cultures. • Only B. animalis subsp. lactis utilized XOS in pure cultures. • B. animalis subsp. lactis could grow on xylan in a co-culture with Bacteroides species. • Results indicate a cross-feeding between Bacteroides and Bifidobacterium. Although most members of the genus Bifidobacterium are unable to utilize xylan as a carbon source, the growth of these species can be induced by this polysaccharide in the gut environment. This indicates a requirement for an association between Bifidobacterium species and some other members of gut microbiota. In this study, the role of cross-feeding between Bifidobacterium and Bacteroides species in the bifidogenic effect of xylan was investigated using in-vitro pure and co-culture fermentations. The pure culture studies showed that among the Bifidobacterium species tested, only Bifidobacterium animalis subsp. lactis was able to utilize xylooligosaccharides. The co-culture of this strain with Bacteroides species enabled it to grow in the presence of xylan. These results suggest that the ability of Bacteroides species to hydrolyze xylan could allow the proliferation of specific Bifidobacterium species in the gut through substrate cross-feeding. [ABSTRACT FROM AUTHOR]

Microbial biodegradation of hydrocarbons in petroleum reservoirs has major consequences in the petroleum value and quality. The identification of microorganisms capable of in-situ degradation of hydrocarbons under the reservoir conditions is crucial to understand microbial roles in hydrocarbon transformation and the impact of oil exploration and production on energy resources. The aim of this study was to profile the metagenome of microbial communities in crude oils and associated formation water from two high temperature and relatively saline oil-production wells, where one has been subjected to water flooding (BA-2) and the other one is considered pristine (BA-1). The microbiome was studied in the fluids using shotgun metagenome sequencing. Distinct microbial compositions were revealed when comparing pristine and water flooded oil wells in contrast to the similar community structures observed between the aqueous and oil fluids from the same well (BA-2). The equal proportion of archaea and bacteria together with the greater anaerobic hydrocarbon degradation potential in the BA-1 pristine but degraded reservoir contrasted with the predominance of bacteria over archaea, aerobic pathways and lower frequency of anaerobic degradation genes in the BA-2 water flooded undegraded well. Our results suggest that Syntrophus , Syntrophom on as , candidatus Atribacteria and Synergistia, in association with mainly acetoclastic methanogenic archaea of the genus Methanothrix , were collectively responsible for the oil biodegradation observed in the pristine petroleum well BA-1. Conversely, the microbial composition of the water flooded oil well BA-2 was mainly dominated by the fast-growing and putatively aerobic opportunists Marinobacter and Marinobacterium. This presumable allochthonous community introduced a greater metabolic versatility, although oil biodegradation has not been detected hitherto perhaps due to in-reservoir unfavorable physicochemical conditions. These findings provide a better understanding of the petroleum reservoir microbiomes and their potential roles in biogeochemical processes occurring in environments with different geological and oil recovery histories. Unlabelled Image • Taxonomy and potential for hydrocarbon degradation of a pristine and a water-flooded oil reservoir, were explored. • Higher abundance of anaerobic hydrocarbon degradation and methanogenesis were found in the pristine biodegraded oil. • Hydrocarbon degraders were members of genera Syntrophus and Syntrophomonas , and of Ca. Atribacteria and Synergistia phyla • Marinobacter and Marinobacterium dominated the water-flooded petroleum reservoir as consequence of seawater injection [ABSTRACT FROM AUTHOR]

Recent efforts have focused on providing a systematic analysis of syntrophic microbial growth yields. These biokinetic parameters are key to developing an accurate mathematical description of the anaerobic digestion process. The agreement between experimentally determined growth yields and those obtained from bioenergetic estimations is therefore of great interest. Considering five important syntrophic groups, including acetoclastic and hydrogenotrophic methanogens, as well as propionate, butyrate and lactate oxidizers, previous findings suggest that measured and estimated growth yields were consistent only for acetoclastic methanogens. A re-analysis revealed that data are also consistent for lactate oxidizers and hydrogenotrophic methanogens, whereas the limited data available for propionate and butyrate oxidizers are unsupportive of firm conclusions. These results highlight pertinent challenges in the analysis of microbial syntrophy and encourage more accurate measurements of syntrophic microbial growth yields in the future. • Syntrophic growth yields play a key role in anaerobic digestion. • Measured growth yields were compared to bioenergetic estimations. • Results are consistent for methanogens and anaerobic lactate oxidizers. • Limited data on butyrate and propionate oxidizers prevent firm conclusions. • Reliable measurements of syntrophic microbial growth yields remain scarce. [ABSTRACT FROM AUTHOR]

• In-situ H 2 -assisted biogas upgrading was applied to anaerobic wastewater treatment. • CH 4 content of product gas was consistently over 90% at all OLRs. • H 2 -rich syngas could replace pure H 2 during the in-situ biogas upgrading process. • Syntrophy of bacteria and methanogens facilitated biogas upgrading with syngas. • Aceticlastic Methanothrix species were the dominant methanogens in the reactors. The H 2 -assisted biogas upgrading approach has recently attracted much interest as a low-cost and environmentally friendly alternative to commonly used ex-situ/ physiochemical biogas upgrading techniques. However, most studies conducted to date have been limited to anaerobic solid-waste treatment characterized by flocculant sludge and low organic loading rates (OLR). In an attempt to expand its application to high-rate anaerobic wastewater treatment, an innovative two-stage up-flow anaerobic sludge blanket reactor system was employed using anaerobic granular sludge. We found that the CH 4 content of product gas was consistently >90% and that H 2 and CO 2 concentrations stayed below 5%, even when OLR was increased from 1 to 5 g L−1 d−1 and H 2 feeding rates were increased from 0.13 to 0.63 g L−1 d−1. We were also able to show that CO (5–10%) in H 2 -rich syngas didn't inhibit methanogenesis or had significant impact on microbial community structure, suggesting that H 2 -assisted biogas upgrading with H 2 -rich syngas is feasible. [ABSTRACT FROM AUTHOR]

This article outlines the proposed 'syntrophic imbalance hypothesis' for etiology of bacterial endoparasitism diseases. This hypothesis involves microbes (archaea and bacteria) that exist in human body biofilms in syntrophic associations, where bacteria ferment nutrients to produce short chain fatty acids (SCFAs) that are used by methanogenic archaeons to produce methane. Overgrowth of archaea on human tissues (e.g., in association with intestines, teeth or lungs) results in excessive removal of SCFAs from the biofilms and this triggers bacteria in the free-living biofilm state to convert to the endoparasitic state and become intracellular in host cells where they incite inflammation and disease. The proposed model provides the mechanism to explain dysbiosis etiology of several human diseases, including gingivitis, leaky gut syndrome, Crohn's disease, irritable bowel syndrome, among others. [ABSTRACT FROM AUTHOR]

• Effect of microbial density on syntrophic acetogens and methanogens was revealed. • AHLs secretion of acetogens and methanogens were affected by microbial density. • Social behavior of syntrophic acetogens and methanogens was mediated by the AHLs. • Mediation of endogenous AHLs between acetogens and methanogens was networked. • Microbial density control was a feasible approach to regulate endogenous AHLs in AD. To understand the syntrophic mechanism of acetogens and methanogens in anaerobic digestion (AD), functional floras of syntrophic propionate-oxidizing bacteria (SPOB), syntrophic butyrate-oxidizing bacteria (SBOB), aceticlastic methanogens (AM) and hydrogenotrophic methanogens (HM) were separately tested by microbial density to reveal their performance in metabolic activity, extracellular polymeric substances (EPS) production and quorum sensing (QS) signal molecules (acyl homoserine lactones, AHLs) secretion, as well as the regulation of endogenous AHLs in balancing the social behaviors of syntrophic microorganism. The results showed that methanogenesis, EPS production and AHLs secretion of the functional floras were all observably affected by microbial density. The metabolic activity of SBOB, SPOB, AM and HM decreased with a microbial density more than 344, 295, 229 and 237 mgMLVSS/L, respectively. The intraspecific regulation of SPOB and HM were achieved with the mediation of OXOC6-HSL and C10-HSL, respectively. With the mediation of enjoyed signal molecules, metabolic coordination between SPOB and AM was of bidirectional regulation, but it was a unidirectional regulation from HM to SPOB. Syntrophic acetogens and methanogens in AD could bidirectionally regulate their EPS production via QS system to construct syntrophic floras that make the methane fermentation of propionate and butyrate more efficient. The present research work provides a practical strategy to regulate endogenous AHLs by microbial density to enhance the syntrophism of acetogens and methanogens in AD. [ABSTRACT FROM AUTHOR]

Although the enhancement of anammox performance for wastewater treatment due to the addition of small amount of acetate has been reported, discrepant metabolic responses of different anammox species have not been experimentally evaluated. Based on metagenomics and metatranscriptomic data, we investigated the competitiveness between two typical anammox species, Candidatus Jettenia caeni (J. caeni) and Candidatus Brocadia sinica (B. sinica) , in anammox consortia under mixotrophic condition, where complex metabolic interactions among anammox bacteria and heterotrophs also changed with acetate addition. Contrary to J. caeni , the dissimilatory nitrate reduction to ammonium pathway of B. sinica was markedly stimulated for improving nitrogen removal. More acetate metabolic pathways and up-regulated AMP- acs expression for acetyl-CoA synthesis in B. sinica contributed to its superiority in acetate utilization. Interestingly, cross-feedings, including the nitrogen cycle, amino acid cross-feeding and B-vitamin metabolic exchange between B. sinica and other heterotrophs seemed to be enhanced with acetate addition, contributing to a reduction in metabolic energy cost to the whole community. Our work not only clarified the mechanism underlying discrepant responses of different anammox species to acetate, but also suggests a possible strategy for obtaining higher nitrogen removal rates in wastewater treatment under low C/N ratio. Image 1 • In presence of acetate (C/N = 0.3), B. sin ica was more competitive than J. caeni. • B. sinica owns diverse metabolic pathways and superior acs gene for using acetate. • Amino acids cross-feeding in anammox community could be promoted by acetate. • B-vitamin exchange between B. sinica and heterotrophs was strengthened by acetate. [ABSTRACT FROM AUTHOR]

• Addition of polysaccharidic wastes in digesters enhanced the methane yield by 75%. • Prevotella , Eubacterium , and Lachnoclostridium were major saccharolytic bacteria. • Dominance of Methanosaeta suggests acetoclastic methanogenesis as prevalent pathway. • Acetoclastic methanogens showed associations with propionate oxidizers. Compositional variations in organic wastes influence microbial abundancy and syntrophy during anaerobic digestion (AD), impacting the normal performance of digesters for methanation. Investigation of the microbial dynamics during AD following augmentation with polysaccharidic wastes (PW) revealed the association of effective digester performance and methane yields with the microbial nexus. Dominance of the acidogenic saccharolytic genera, Prevotella , Eubacterium , and Lachnoclostridium , enhanced the utilization of carbohydrates (54%) in PW-augmented digesters. Spearman's rs correlation showed dynamic interspecies interactions among acetogenic syntrophs, and that of iron oxidizers/reducers with acetoclastic and hydrogenotrophic methanogens. Propionate oxidizers in Chloroflexi (i.e. , Bellilinea , Levilinea , and Longilinea) exhibited positive associations with acetoclastic methanogens. Increase in the population of acetoclastic methanogens (Methanosaeta , 77% and Methanosarcina , 9%) accelerated the methanogenic activity of PW-augmented digesters by 7 times during the exponential phase, increasing the methane yield (75%) compared to the control. Thus, microbial syntrophy facilitated the effective methanation of PW during AD process. [ABSTRACT FROM AUTHOR]

Background: Substrate cross-feeding occurs when one organism partially consumes a primary substrate into one or more metabolites while other organisms then consume the metabolites. While pervasive within microbial communities, our knowledge about the effects of substrate cross-feeding on microbial evolution remains limited. To address this knowledge gap, we experimentally evolved isogenic nitrite (NO2−) cross-feeding microbial strains together for 700 generations, identified genetic changes that were acquired over the evolution experiment, and compared the results with an isogenic completely denitrifying strain that was evolved alone for 700 generations. We further investigated how the magnitude of interdependence between the nitrite cross-feeding strains affects the main outcomes. Our main objective was to quantify how substrate cross-feeding and the magnitude of interdependence affect the speed and trajectory of molecular evolution. Results: We found that each nitrite (NO2−) cross-feeding strain acquired fewer genetic changes than did the completely denitrifying strain. In contrast, pairs of nitrite cross-feeding strains together acquired more genetic changes than did the completely denitrifying strain. Moreover, nitrite cross-feeding promoted population diversification, as pairs of nitrite cross-feeding strains acquired a more varied set of genetic changes than did the completely denitrifying strain. These outcomes likely occurred because nitrite cross-feeding enabled the co-existence of two distinct microbial strains, thus increasing the amount of genetic variation for selection to act upon. Finally, the nitrite cross-feeding strains acquired different types of genetic changes than did the completely denitrifying strain, indicating that nitrite cross-feeding modulates the trajectory of molecular evolution. Conclusions: Our results demonstrate that substrate cross-feeding can affect both the speed and trajectory of molecular evolution within microbial populations. Substrate cross-feeding can therefore have potentially important effects on the life histories of microorganisms. [ABSTRACT FROM AUTHOR]

Understanding the principles that govern the assembly of microbial communities across earth's biomes is a major challenge in modern microbial ecology. This pursuit is complicated by the difficulties of mapping functional roles and interactions onto communities with immense taxonomic diversity and of identifying the scale at which microbes interact [ 1 ]. To address this challenge, here, we focused on the bacterial communities that colonize and degrade particulate organic matter in the ocean [ 2–4 ]. We show that the assembly of these communities can be simplified as a linear combination of functional modules. Using synthetic polysaccharide particles immersed in natural bacterioplankton assemblages [ 1, 5 ], we showed that successional particle colonization dynamics are driven by the interaction of two types of modules: a first type made of narrowly specialized primary degraders, whose dynamics are controlled by particle polysaccharide composition, and a second type containing substrate-independent taxa whose dynamics are controlled by interspecific interactions—in particular, cross-feeding via organic acids, amino acids, and other metabolic byproducts. We show that, as a consequence of this trophic structure, communities can assemble modularly—i.e., by a simple sum of substrate-specific primary degrader modules, one for each complex polysaccharide in the particle, connected to a single broad-niche range consumer module. Consistent with this model, a linear combination of the communities on single-polysaccharide particles accurately predicts community composition on mixed-polysaccharide particles. Our results suggest that the assembly of heterotrophic communities that degrade complex organic materials follows simple design principles that could be exploited to engineer heterotrophic microbiomes. • Complex marine microbial communities are composed of functional groups • Functional groups occupy trophic levels connected by metabolic cross-feeding • Communities assemble by recruiting these functional groups in a modular fashion • Community composition can be predicted based on substrate composition Enke et al. show that particle-attached marine microbial communities assemble by recruiting functional groups of taxa in an additive manner. Specialist groups degrade specific polysaccharides, whereas generalist byproduct utilizers invade independently of particle substrate. This simple organization allows prediction of community structure. [ABSTRACT FROM AUTHOR]

Anchialine sinkholes provide insight into coastal aquifer systems and coastal mixing processes. Aquifer microbial community function is usually inferred from hydrochemical information, but there are few direct studies of microbial communities in the Floridan Aquifer. Hospital Hole is a 43 m-deep stratified sinkhole under the Weeki Wachee River, FL, with three distinct brackish layers: a hypoxic layer, a chemocline and a sulfidic anoxic layer. Illumina sequencing and bioinformatic tools were used to reconstruct metabolic functions and interactions of microbial communities in each layer. Each layer appears to originate from different parts of the coastal mixing zone and has a distinct microbial community with unique functions, which are influenced by the respective hydrochemistry. Sulfide oxidation and nitrate reduction are the most abundant functions. Syntrophy between methane oxidizers, methanogens and sulfate reducers is present. Similarities between the hydrochemistry and potential connectivity of Hospital Hole and the Floridan Aquifer coastal mixing zone suggest that microbial communities of Hospital Hole could be a surrogate for the coastal mixing zone of the aquifer in the absence of direct studies. Understanding how groundwater microbial communities react to saltwater intrusion and nutrient flux will be useful in predicting how coastal aquifer regions might react to anthropogenic change. [ABSTRACT FROM AUTHOR]

The article reports on two studies regarding pathological conditions in case of cystic fibrosis (CF). It discusses a study in which it has been hypothesized that specie of Pseudomonas aeruginosa develops syntrophy with the pulmonary environment in patients with CF. It also discusses a study that has been conducted to determine similarity between nasal polyps found in case of cystic fibrosis with that of found in non-CF-related sinusitis.

The article focuses on a multi-omics systems-based workflow in exploring the details about the syntrophic relationship between two Geobacter species. It offers information about syntrophic interactions, wherein two or more microorganisms unite metabolically in metabolizing compounds that neither partner can metabolize alone. Information about direct interspecies electron transfer is provided.