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Environmental Microbiology Reports Jun 2024Syntrophic interactions are key in anaerobic food chains, facilitating the conversion of complex organic matter into methane. A typical example involves acetogenic...
Syntrophic interactions are key in anaerobic food chains, facilitating the conversion of complex organic matter into methane. A typical example involves acetogenic bacteria converting fatty acids (e.g., butyrate and propionate), a process thermodynamically reliant on H consumption by microorganisms such as methanogens. While most studies focus on H-interspecies transfer between these groups, knowledge on acetate cross-feeding in anaerobic systems is lacking. This study investigated butyrate oxidation by co-cultures of Syntrophomonas wolfei and Methanospirillum hungatei, both with and without the addition of the acetate scavenger Methanothrix soehngenii. Growth and gene expression patterns of S. wolfei and M. hungatei were followed in the two conditions. Although butyrate consumption rates remained constant, genes in the butyrate degradation pathway of S. wolfei were less expressed in the presence of M. soehngenii, including genes involved in reverse electron transport. Higher expression of a type IV-pili operon in S. wolfei hints to the potential for direct interspecies electron transfer between S. wolfei and M. soehngenii and an energetically advantageous relationship between the two microorganisms. Overall, the presence of the acetate scavenger M. soehngenii positively influenced the energy metabolism of S. wolfei and highlighted the relevance of including acetate scavengers when investigating syntrophic fatty acid degradation.
Topics: Methanospirillum; Butyrates; Transcriptome; Anaerobiosis; Oxidation-Reduction; Acetates; Microbial Interactions; Methane; Coculture Techniques; Electron Transport
PubMed: 38733087
DOI: 10.1111/1758-2229.13276 -
International Journal of Molecular... May 2024Metals are dispersed in natural environments, particularly in the aquatic environment, and accumulate, causing adverse effects on aquatic life. Moreover, chronic... (Review)
Review
Metals are dispersed in natural environments, particularly in the aquatic environment, and accumulate, causing adverse effects on aquatic life. Moreover, chronic polymetallic water pollution is a common problem, and the biological effects of exposure to complex mixtures of metals are the most difficult to interpret. In this review, metal toxicity is examined with a focus on its impact on energy metabolism. Mechanisms regulating adenosine triphosphate (ATP) production and reactive oxygen species (ROS) emission are considered in their dual roles in the development of cytotoxicity and cytoprotection, and mitochondria may become target organelles of metal toxicity when the transmembrane potential is reduced below its phosphorylation level. One of the main consequences of metal toxicity is additional energy costs, and the metabolic load can lead to the disruption of oxidative metabolism and enhanced anaerobiosis.
Topics: Animals; Adenosine Triphosphate; Energy Metabolism; Fishes; Metals; Mitochondria; Oxidative Stress; Reactive Oxygen Species; Water Pollutants, Chemical
PubMed: 38732234
DOI: 10.3390/ijms25095015 -
International Journal of Molecular... Apr 2024Recently, the increase in marine temperatures has become an important global marine environmental issue. The ability of energy supply in marine animals plays a crucial...
Recently, the increase in marine temperatures has become an important global marine environmental issue. The ability of energy supply in marine animals plays a crucial role in avoiding the stress of elevated temperatures. The investigation into anaerobic metabolism, an essential mechanism for regulating energy provision under heat stress, is limited in mollusks. In this study, key enzymes of four anaerobic metabolic pathways were identified in the genome of scallop , respectively including five opine dehydrogenases (CfOpDHs), two aspartate aminotransferases (CfASTs) divided into cytoplasmic (CfAST1) and mitochondrial subtype (CfAST2), and two phosphoenolpyruvate carboxykinases (CfPEPCKs) divided into a primitive type (CfPEPCK2) and a cytoplasmic subtype (CfPEPCK1). It was surprising that lactate dehydrogenase (LDH), a key enzyme in the anaerobic metabolism of the glucose-lactate pathway in vertebrates, was absent in the genome of scallops. Phylogenetic analysis verified that CfOpDHs clustered according to the phylogenetic relationships of the organisms rather than substrate specificity. Furthermore, , , and displayed distinct expression patterns throughout the developmental process and showed a prominent expression in muscle, foot, kidney, male gonad, and ganglia tissues. Notably, displayed the highest level of expression among these genes during the developmental process and in adult tissues. Under heat stress, the expression of exhibited a general downregulation trend in the six tissues examined. The expression of also displayed a downregulation trend in most tissues, except in striated muscle showing significant up-regulation at some time points. Remarkably, was significantly upregulated in all six tested tissues at almost all time points. Therefore, we speculated that the glucose-succinate pathway, catalyzed by , serves as the primary anaerobic metabolic pathway in mollusks experiencing heat stress, with catalyzing the glucose-opine pathway in striated muscle as supplementary. Additionally, the high and stable expression level of is crucial for the maintenance of the essential functions of aspartate aminotransferase (AST). This study provides a comprehensive and systematic analysis of the key enzymes involved in anaerobic metabolism pathways, which holds significant importance in understanding the mechanism of energy supply in mollusks.
Topics: Animals; Pectinidae; Glucose; Heat-Shock Response; Anaerobiosis; Phylogeny; Succinic Acid; Metabolic Networks and Pathways; Aspartate Aminotransferases
PubMed: 38731961
DOI: 10.3390/ijms25094741 -
Molecules (Basel, Switzerland) Apr 2024The antibacterial effects of a selection of volatile fatty acids (acetic, propionic, butyric, valeric, and caproic acids) relevant to anaerobic digestion were...
The antibacterial effects of a selection of volatile fatty acids (acetic, propionic, butyric, valeric, and caproic acids) relevant to anaerobic digestion were investigated at 1, 2 and 4 g/L. The antibacterial effects were characterised by the dynamics of NCTC 00775, JCM 1649 and A17. Mesophilic anaerobic incubation to determine the minimum bactericidal concentration (MBC) and median lethal concentration of the VFAs was carried out in Luria Bertani broth at 37 °C for 48 h. Samples collected at times 0, 3, 6, 24 and 48 h were used to monitor bacterial kinetics and pH. VFAs at 4 g/L demonstrated the highest bactericidal effect ( < 0.05), while 1 g/L supported bacterial growth. The VFA cocktail was the most effective, while propionic acid was the least effective. NCTC 00775 was the most resistant strain with the VFAs MBC of 4 g/L, while A17 was the least resistant with the VFAs MBC of 2 g/L. Allowing a 48 h incubation period led to more log decline in the bacterial numbers compared to earlier times. The VFA cocktail, valeric, and caproic acids at 4 g/L achieved elimination of the three bacteria strains, with over 7 log decrease within 48 h.
Topics: Fatty Acids, Volatile; Anti-Bacterial Agents; Enterococcus faecalis; Klebsiella pneumoniae; Microbial Sensitivity Tests; Anaerobiosis; Escherichia coli; Propionates; Hydrogen-Ion Concentration; Pentanoic Acids
PubMed: 38731399
DOI: 10.3390/molecules29091908 -
Scientific Reports May 2024Our study investigates the effects of iron oxide (FeO) nanoparticles combined microwave pretreatment on the anaerobic digestibility and soluble chemical oxygen demand...
Our study investigates the effects of iron oxide (FeO) nanoparticles combined microwave pretreatment on the anaerobic digestibility and soluble chemical oxygen demand (SCOD) of meat industry sludge. One of our main objectives was to see whether the different microwave-based pretreatment procedures can enhance biogas production by improving the biological availability of organic compounds. Results demonstrated that combining microwave irradiation with magnetic iron oxide nanoparticles considerably increased SCOD (enhancement ratio was above 1.5), the rate of specific biogas production, and the total cumulative specific biogas volume (more than a threefold increment), while having no negative effect on the biomethane content. Furthermore, the assessment of the sludge samples' dielectric properties (dielectric constant and loss factor measured at the frequency of 500 MHz) showed a strong correlation with SCOD changes (r = 0.9942, R = 0.99), offering a novel method to evaluate pretreatment efficiency.
Topics: Microwaves; Sewage; Magnetic Iron Oxide Nanoparticles; Anaerobiosis; Meat; Biological Oxygen Demand Analysis; Biofuels; Food Industry; Industrial Waste
PubMed: 38730012
DOI: 10.1038/s41598-024-61423-6 -
Journal of Environmental Management May 2024The impact of climate change on water availability and quality has affected agricultural irrigation. The use of treated wastewater can alleviate water in agriculture....
Demo-scale up-flow anaerobic sludge blanket reactor coupled with hybrid constructed wetlands for energy-carbon efficient agricultural wastewater reuse in decentralized scenarios.
The impact of climate change on water availability and quality has affected agricultural irrigation. The use of treated wastewater can alleviate water in agriculture. Nevertheless, it is imperative to ensure proper treatment of wastewater before reuse, in compliance with current regulations of this practice. In decentralized agricultural scenarios, the lack of adequate treatment facilities poses a challenge in providing treated wastewater for irrigation. Hence, there is a critical need to develop and implement innovative, feasible, and sustainable treatment solutions to secure the use of this alternative water source. This study proposes the integration of intensive treatment solutions and natural treatment systems, specifically, the combination of up-flow anaerobic sludge blanket reactor (UASB), anaerobic membrane bioreactor (AnMBR), constructed wetlands (CWs), and ultraviolet (UV) disinfection. For this purpose, a novel demo-scale plant was designed, constructed and implemented to test wastewater treatment and evaluate the capability of the proposed system to provide an effluent with a quality in compliance with the current European wastewater reuse regulatory framework. In addition, carbon-sequestration and energy analyses were conducted to assess the sustainability of the proposed treatment approach. This research confirmed that UASB rector can be employed for biogas production (2.5 L h) and energy recovery from organic matter degradation, but its effluent requires further treatment steps to be reused in agricultural irrigation. The AnMBR effluent complied with class A standards for E. coli, boasting a concentration of 0 CFU 100 mL, and nearly negligible TSS levels. However, further reduction of BOD (35 mg L) is required to reach water quality class A. CWs efficiently produced effluent with BOD below 10 mg L and TSS close to 0 mg L, making it suitable for water reuse and meeting class A standards. Furthermore, CWs demonstrated significantly higher energy efficiency compared to intensive treatment systems. Nonetheless, the inclusion of a UV disinfection unit after CWs was required to attain water class B standards.
Topics: Wetlands; Wastewater; Bioreactors; Anaerobiosis; Waste Disposal, Fluid; Sewage; Agriculture; Carbon
PubMed: 38723500
DOI: 10.1016/j.jenvman.2024.121109 -
Water Research Jun 2024Hydrothermal liquefaction (HTL) is a promising thermo-chemical technology for municipal sludge treatment due to its potential for biocrude oil recovery and minimizing...
Hydrothermal liquefaction (HTL) is a promising thermo-chemical technology for municipal sludge treatment due to its potential for biocrude oil recovery and minimizing biosolids management costs. However, the process generates a high volume of an aqueous byproduct that needs to be treated due to its high chemical oxygen demand (COD) and various organic and inorganic compounds. Although the aqueous phase is known to contain recalcitrant and potentially inhibitory substances that may affect its biological treatment, their molecular weight distribution (MwD) and its impact on anaerobic biodegradability are poorly understood. Ultrafiltration (UF) was conducted to fractionate HTL aqueous into different molecular weight (Mw) fractions using 300, 100, 10, and 1 kDa membranes. Mesophilic biochemical methane potential (BMP) assays were conducted to assess the anaerobic biodegradability of each fraction, and the first-order model was used to calculate the degradation kinetics of potential inhibitory compounds. The highest percentage of organics (65 %) was found in the Mw<1 kDa range, whereas the 10>Mw>1 kDa had the lowest percentage (8 %). There was no significant difference in the cumulative specific methane produced from various Mw fractions (p>0.05). The Mw<1 kDa fraction had the highest first-order specific methane production rate (0.53 day), whereas the unfiltered HTL had the lowest (0.38 day). Although UF fractionation increased the rate of anaerobic degradation of HTL aqueous for the Mw<1 kDa fraction, the observed methane potential was only 55 % of the theoretical value. This implies that 45 % of COD remains undegraded even after permeation through the lowest Mw cut-off membrane. Therefore, further characterization of HTL aqueous is needed for compounds with molecular weights below 1 kDa to fully understand the nature of inhibitory organics and their impact on anaerobic digestion. Furthermore, pretreatments utilizing techniques such as adsorption and advanced oxidation may be necessary to enhance the specific methane yields from various HTL aqueous fractions, thereby bringing them closer to the theoretical yield.
Topics: Sewage; Ultrafiltration; Methane; Anaerobiosis; Molecular Weight; Waste Disposal, Fluid; Biological Oxygen Demand Analysis; Biodegradation, Environmental
PubMed: 38723354
DOI: 10.1016/j.watres.2024.121703 -
BMC Biotechnology May 2024This research investigates the efficacy of a high-performance pilot-scale Internal Circulation Anaerobic Reactor inoculated with Granular Sludge (ICAGSR) for treating...
This research investigates the efficacy of a high-performance pilot-scale Internal Circulation Anaerobic Reactor inoculated with Granular Sludge (ICAGSR) for treating cattle slaughterhouse wastewater while concurrently generating biogas. The primary objective is to assess the efficiency and performance of ICAGSR in terms of organic pollutant removal and biogas production using granular anaerobic sludge. The research methodology entails operating the ICAGSR system under ambient conditions and systematically varying key parameters, including different Hydraulic Retention Times (HRTs) (24, 12, and 8 h) and Organic Loading Rates (OLRs) (3.3, 6.14, and 12.83 kg COD/m³. d). The study focuses on evaluating pollutants' removal and biogas production rates. Results reveal that the ICAGSR system achieves exceptional removal efficiency for organic pollutants, with Chemical Oxygen Demand (COD) removal exceeding 74%, 67%, and 68% at HRTs of 24, 12, and 8 h, respectively. Furthermore, the system demonstrates stable and sustainable biogas production, maintaining average methane contents of 80%, 76%, and 72% throughout the experimental period. The successful operation of the ICAGSR system underscores its potential as a viable technology for treating cattle slaughterhouse wastewater and generating renewable biogas. In conclusion, this study contributes to wastewater treatment and renewable energy production by providing a comprehensive analysis of the ICAGSR system's hydrodynamic properties. The research enhances our understanding of the system's performance optimization under varying conditions, emphasizing the benefits of utilizing ICAGSR reactors with granular sludge as an effective and sustainable approach. Identifying current gaps, future research directions aim to further refine and broaden the application of ICAGSR technology in wastewater treatment and renewable energy initiatives.
Topics: Animals; Cattle; Bioreactors; Abattoirs; Biofuels; Sewage; Wastewater; Anaerobiosis; Waste Disposal, Fluid; Methane; Biological Oxygen Demand Analysis
PubMed: 38720285
DOI: 10.1186/s12896-024-00849-2 -
The Science of the Total Environment Jul 2024Perfluorooctane sulfonate (PFOS), one of the most frequently detected per- and polyfluoroalkyl substances (PFAS) occurring in soil, surface water, and groundwater near...
Perfluorooctane sulfonate (PFOS), one of the most frequently detected per- and polyfluoroalkyl substances (PFAS) occurring in soil, surface water, and groundwater near sites contaminated with aqueous film-forming foam (AFFF), has proven to be recalcitrant to many destructive remedies, including chemical oxidation. We investigated the potential to utilize microbially mediated reduction (bioreduction) to degrade PFOS and other PFAS through addition of a known dehalogenating culture, WBC-2, to soil obtained from an AFFF-contaminated site. A substantial decrease in total mass of PFOS (soil and water) was observed in microcosms amended with WBC-2 and chlorinated volatile organic compound (cVOC) co-contaminants - 46.4 ± 11.0 % removal of PFOS over the 45-day experiment. In contrast, perfluorooctanoate (PFOA) and 6:2 fluorotelomer sulfonate (6:2 FTS) concentrations did not decrease in the same microcosms. The low or non-detectable concentrations of potential metabolites in full PFAS analyses, including after application of the total oxidizable precursor assay, indicated that defluorination occurred to non-fluorinated compounds or ultrashort-chain PFAS. Nevertheless, additional research on the metabolites and degradation pathways is needed. Population abundances of known dehalorespirers did not change with PFOS removal during the experiment, making their association with PFOS removal unclear. An increased abundance of sulfate reducers in the genus Desulfosporosinus (Firmicutes) and Sulfurospirillum (Campilobacterota) was observed with PFOS removal, most likely linked to initiation of biodegradation by desulfonation. These results have important implications for development of in situ bioremediation methods for PFAS and advancing knowledge of natural attenuation processes.
Topics: Fluorocarbons; Alkanesulfonic Acids; Biodegradation, Environmental; Soil Pollutants; Soil Microbiology; Anaerobiosis; Halogenation; Solvents; Soil; Microbiota
PubMed: 38719042
DOI: 10.1016/j.scitotenv.2024.172996 -
PLoS Genetics May 2024The capacity for bacterial extracellular electron transfer via secreted metabolites is widespread in natural, clinical, and industrial environments. Recently, we...
The capacity for bacterial extracellular electron transfer via secreted metabolites is widespread in natural, clinical, and industrial environments. Recently, we discovered the biological oxidation of phenazine-1-carboxylic acid (PCA), the first example of biological regeneration of a naturally produced extracellular electron shuttle. However, it remained unclear how PCA oxidation was catalyzed. Here, we report the mechanism, which we uncovered by genetically perturbing the branched electron transport chain (ETC) of the soil isolate Citrobacter portucalensis MBL. Biological PCA oxidation is coupled to anaerobic respiration with nitrate, fumarate, dimethyl sulfoxide, or trimethylamine-N-oxide as terminal electron acceptors. Genetically inactivating the catalytic subunits for all redundant complexes for a given terminal electron acceptor abolishes PCA oxidation. In the absence of quinones, PCA can still donate electrons to certain terminal reductases, albeit much less efficiently. In C. portucalensis MBL, PCA oxidation is largely driven by flux through the ETC, which suggests a generalizable mechanism that may be employed by any anaerobically respiring bacterium with an accessible cytoplasmic membrane. This model is supported by analogous genetic experiments during nitrate respiration by Pseudomonas aeruginosa.
Topics: Phenazines; Oxidation-Reduction; Electron Transport; Soil Microbiology; Citrobacter; Anaerobiosis; Bacterial Proteins
PubMed: 38709821
DOI: 10.1371/journal.pgen.1011064