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Water Research Jun 2024Phage emit communication signals that inform their lytic and lysogenic life cycles. However, little is known regarding the abundance and diversity of the genes...
Phage emit communication signals that inform their lytic and lysogenic life cycles. However, little is known regarding the abundance and diversity of the genes associated with phage communication systems in wastewater treatment microbial communities. This study focused on phage communities within two distinct biochemical wastewater environments, specifically aerobic membrane bioreactors (AeMBRs) and anaerobic membrane bioreactors (AnMBRs) exposed to varying antibiotic concentrations. Metagenomic data from the bench-scale systems were analyzed to explore phage phylogeny, life cycles, and genetic capacity for antimicrobial resistance and quorum sensing. Two dominant phage families, Schitoviridae and Peduoviridae, exhibited redox-dependent dynamics. Schitoviridae prevailed in anaerobic conditions, while Peduoviridae dominated in aerobic conditions. Notably, the abundance of lytic and lysogenic proteins varied across conditions, suggesting the coexistence of both life cycles. Furthermore, the presence of antibiotic resistance genes (ARGs) within viral contigs highlighted the potential for phage to transfer ARGs in AeMBRs. Finally, quorum sensing genes in the virome of AeMBRs indicated possible molecular signaling between phage and bacteria. Overall, this study provides insights into the dynamics of viral communities across varied redox conditions in MBRs. These findings shed light on phage life cycles, and auxiliary genetic capacity such as antibiotic resistance and bacterial quorum sensing within wastewater treatment microbial communities.
Topics: Bioreactors; Bacteriophages; Anaerobiosis; Phylogeny; Quorum Sensing; Drug Resistance, Microbial; Wastewater; Aerobiosis
PubMed: 38677036
DOI: 10.1016/j.watres.2024.121620 -
Polish Journal of Microbiology Jun 2024Electricigens decompose organic matter and convert stored chemical energy into electrical energy through extracellular electron transfer. They are significant...
Electricigens decompose organic matter and convert stored chemical energy into electrical energy through extracellular electron transfer. They are significant biocatalysts for microbial fuel cells with practical applications in green energy generation, effluent treatment, and bioremediation. A facultative anaerobic electrogenic strain SQ-1 is isolated from sludge in a biotechnology factory. The strain SQ-1 is a close relative of . Multilayered biofilms form on the surface of a carbon electrode after the isolated bacteria are inoculated into a microbial fuel cell device. This strain produces high current densities of 625 μA cm by using acetate as the carbon source in a three-electrode configuration. The electricity generation performance is also analyzed in a dual-chamber microbial fuel cell. It reaches a maximum power density of 560 mW m when the corresponding output voltage is 0.59 V. The facultative strain SQ-1 utilizes hydrous ferric oxide as an electron acceptor to perform extracellular electricigenic respiration in anaerobic conditions. Since facultative strains possess better properties than anaerobic strains, sp. SQ-1 may be a promising exoelectrogenic strain for applications in microbial electrochemistry.
Topics: Klebsiella; Bioelectric Energy Sources; Anaerobiosis; Sewage; Electricity; Electrodes; Biofilms; Phylogeny; Electrochemical Techniques; RNA, Ribosomal, 16S
PubMed: 38676960
DOI: 10.33073/pjm-2024-013 -
Sensors (Basel, Switzerland) Apr 2024This study aims to enhance diagnostic capabilities for optimising the performance of the anaerobic sewage treatment lagoon at Melbourne Water's Western Treatment Plant...
This study aims to enhance diagnostic capabilities for optimising the performance of the anaerobic sewage treatment lagoon at Melbourne Water's Western Treatment Plant (WTP) through a novel machine learning (ML)-based monitoring strategy. This strategy employs ML to make accurate probabilistic predictions of biogas performance by leveraging diverse real-life operational and inspection sensor and other measurement data for asset management, decision making, and structural health monitoring (SHM). The paper commences with data analysis and preprocessing of complex irregular datasets to facilitate efficient learning in an artificial neural network. Subsequently, a Bayesian mixture density neural network model incorporating an attention-based mechanism in bidirectional long short-term memory (BiLSTM) was developed. This probabilistic approach uses a distribution output layer based on the Gaussian mixture model and Monte Carlo (MC) dropout technique in estimating data and model uncertainties, respectively. Furthermore, systematic hyperparameter optimisation revealed that the optimised model achieved a negative log-likelihood (NLL) of 0.074, significantly outperforming other configurations. It achieved an accuracy approximately 9 times greater than the average model performance (NLL = 0.753) and 22 times greater than the worst performing model (NLL = 1.677). Key factors influencing the model's accuracy, such as the input window size and the number of hidden units in the BiLSTM layer, were identified, while the number of neurons in the fully connected layer was found to have no significant impact on accuracy. Moreover, model calibration using the expected calibration error was performed to correct the model's predictive uncertainty. The findings suggest that the inherent data significantly contribute to the overall uncertainty of the model, highlighting the need for more high-quality data to enhance learning. This study lays the groundwork for applying ML in transforming high-value assets into intelligent structures and has broader implications for ML in asset management, SHM applications, and renewable energy sectors.
Topics: Bayes Theorem; Neural Networks, Computer; Anaerobiosis; Biofuels; Calibration; Monte Carlo Method; Sewage; Machine Learning
PubMed: 38676155
DOI: 10.3390/s24082537 -
The Science of the Total Environment Jun 2024Drained peatlands in temperate climates are under threat from climate change and human activities. The resulting decomposition of organic matter plays a major role in...
Drained peatlands in temperate climates are under threat from climate change and human activities. The resulting decomposition of organic matter plays a major role in regulating the associated land subsidence rates, yet the determinants of aerobic and anaerobic peat decomposition rates are not fully understood. In this study, we sought to gain insight into the drivers of decomposition rates in botanically diverse peatlands (sedge, reed, wood, and moss dominant) under oxic and anoxic conditions. Peat samples were collected from the anoxic zone and incubated for 24 h (short) and 15 weeks (long) under either oxic or anoxic conditions. CO emissions, hydrolytic and oxidative exoenzyme potential activities, phenolic compound concentrations, and several edaphic factors were measured at the end of each incubation period. We found that 15 weeks of oxygen exposure of anoxic peat samples accelerated the average CO emissions by 3.9-fold. Reed and sedge peat respired more than wood and moss peat under anoxic conditions. Interestingly, CO emissions from anoxic peat layers under permanently anoxic conditions were substantial and given the thickness of peat deposits in the field, such activities may play an important role in long-term land subsidence rates and total CO emissions from drained peatlands. The results from the long-term incubations showed that decomposition rates appear to be also controlled by factors other than oxygen intrusion such as substrate availability. In summary, the botanical composition of the peat matrix, incubation conditions and time of incubation are all important factors that need to be considered when predicting peat decomposition and subsequent land subsidence rates.
Topics: Soil; Anaerobiosis; Wetlands; Aerobiosis; Environmental Monitoring; Climate Change; Carbon Dioxide
PubMed: 38670365
DOI: 10.1016/j.scitotenv.2024.172639 -
PeerJ 2024The appropriate sample handling for human fecal microbiota studies is essential to prevent changes in bacterial composition and quantities that could lead to...
BACKGROUND
The appropriate sample handling for human fecal microbiota studies is essential to prevent changes in bacterial composition and quantities that could lead to misinterpretation of the data.
METHODS
This study firstly identified the potential effect of aerobic and anaerobic fecal sample collection and transport materials on microbiota and quantitative microbiota in healthy and fat-metabolic disorder Thai adults aged 23-43 years. We employed metagenomics followed by 16S rRNA gene sequencing and 16S rRNA gene qPCR, to analyze taxonomic composition, alpha diversity, beta diversity, bacterial quantification, Pearson's correlation with clinical factors for fat-metabolic disorder, and the microbial community and species potential metabolic functions.
RESULTS
Our study successfully obtained microbiota results in percent and quantitative compositions. Each sample exhibited quality sequences with a >99% Good's coverage index, and a relatively plateau rarefaction curve. Alpha diversity indices showed no statistical difference in percent and quantitative microbiota OTU richness and evenness, between aerobic and anaerobic sample transport materials. Obligate and facultative anaerobic species were analyzed and no statistical difference was observed. Supportively, the beta diversity analysis by non-metric multidimensional scale (NMDS) constructed using various beta diversity coefficients showed resembling microbiota community structures between aerobic and anaerobic sample transport groups ( = 0.86). On the other hand, the beta diversity could distinguish microbiota community structures between healthy and fat-metabolic disorder groups ( = 0.02), along with Pearson's correlated clinical parameters (., age, liver stiffness, GGT, BMI, and TC), the significantly associated bacterial species and their microbial metabolic functions. For example, genera such as and in healthy human gut provide functions in metabolisms of cofactors and vitamins, biosynthesis of secondary metabolites against gut pathogens, energy metabolisms, digestive system, and carbohydrate metabolism. These microbial functional characteristics were also predicted as healthy individual biomarkers by LEfSe scores. In conclusion, this study demonstrated that aerobic sample collection and transport (<48 h) did not statistically affect the microbiota and quantitative microbiota analyses in alpha and beta diversity measurements. The study also showed that the short-term aerobic sample collection and transport still allowed fecal microbiota differentiation between healthy and fat-metabolic disorder subjects, similar to anaerobic sample collection and transport. The core microbiota were analyzed, and the findings were consistent. Moreover, the microbiota-related metabolic potentials and bacterial species biomarkers in healthy and fat-metabolic disorder were suggested with statistical bioinformatics (., ).
Topics: Humans; Adult; Gastrointestinal Microbiome; Feces; Thailand; Male; RNA, Ribosomal, 16S; Female; Young Adult; Specimen Handling; Anaerobiosis; Aerobiosis; Metagenomics; Southeast Asian People
PubMed: 38650647
DOI: 10.7717/peerj.17270 -
Chemosphere Jun 2024Organic fraction of municipal solid waste (OFMSW) and waste activated sludge (WAS) are the most produced organic waste streams in urban centres. Their anaerobic...
Organic fraction of municipal solid waste (OFMSW) and waste activated sludge (WAS) are the most produced organic waste streams in urban centres. Their anaerobic co-digestion (AcoD) allows to generate methane (CH) and digestate employable as renewable energy source and soil amendment, respectively, fully in accordance with circular bioeconomy principles. However, the widespread adoption of such technology is limited by relatively low CH yields that fail to bridge the gap between benefits and costs. Among strategies to boost AcoD of OFMSW and WAS, use of conductive materials (CMs) to promote interspecies electron transfer has gained increasing attention. This paper presents one of the few experimental attempts of investigating the effects of four different carbon(C)-based CMs (i.e., granular activated carbon - GAC, graphite - GR, graphene oxide - GO, and carbon nanotubes - CNTs) separately added in semi-continuous AcoD of OFMSW and thickened WAS. The presence of C-based CMs has been observed to improve CH yield of the control process. Specifically, after 63 days of operation (concentrations of GAC and GR of 10.0 g/L and of GO and CNTs of 0.2 g/L), 0.186 NL/g, 0.191 NL/g, 0.203 NL/g, and 0.195 NL/g of CH were produced in reactors supplemented with GAC, GR, GO, and CNTs, respectively, compared to 0.177 NL/g produced in the control process. Likewise, at the end of the test (i.e., after 105 days at concentrations of C-based CMs half of the initial ones), CH yields were 0.193 NL/g, 0.201 NL/g, 0.211 NL/g, and 0.206 NL/g in reactors supplemented with GAC, GR, GO, and CNTs, respectively, compared to 0.186 NL/g of the control process. Especially with regard to GR, GO, and CNTs, results obtained in the present study represent a significant advance of the knowledge on the effects of such C-based CMs to realistic and scalable AD process conditions respect to previous literature.
Topics: Sewage; Anaerobiosis; Methane; Solid Waste; Carbon; Refuse Disposal; Graphite; Bioreactors; Nanotubes, Carbon; Charcoal
PubMed: 38643843
DOI: 10.1016/j.chemosphere.2024.142077 -
Bioelectrochemistry (Amsterdam,... Aug 2024Sulphide oxidising bacteria (SOB) have the potential to be used for bioelectrochemical removal, i.e. oxidation, of sulphide from waste streams. In anaerobic conditions,...
Sulphide oxidising bacteria (SOB) have the potential to be used for bioelectrochemical removal, i.e. oxidation, of sulphide from waste streams. In anaerobic conditions, SOB are able to spatially separate sulphide removal and terminal electron transfer to an electrode and act as a sulphide shuttle. However, it is not fully understood how SOB anaerobically remove sulphide and store charge equivalents, and where in this process sulphur is formed. Therefore, the redox behaviour of sulphide shuttling SOB was investigated at haloalkaline conditions using a glassy carbon rotating disc electrode (RDE) and cyclic voltammetry. Voltammograms of SOB in the absence and presence of sulphide were compared to voltammograms of abiotic sulphur species solutions. Polysulphide and sulphide showed different redox behaviour, with distinct potentials for oxidation of > -0.3 V (vs. Ag/AgCl) for polysulphide and > -0.1 V for sulphide. Comparing biotic to abiotic experiments lead to the hypothesis that SOB formed polysulphides during anaerobic sulphide removal, which stayed sorbed to the cells. With this study, further steps were taken in elucidating the mechanisms of sulphide shuttling by SOB.
Topics: Sulfides; Electrodes; Oxidation-Reduction; Bacteria; Electrochemical Techniques; Anaerobiosis
PubMed: 38636364
DOI: 10.1016/j.bioelechem.2024.108710 -
FEMS Microbiology Ecology Apr 2024Aquatic ecosystems are large contributors to global methane (CH4) emissions. Eutrophication significantly enhances CH4-production as it stimulates methanogenesis....
Aquatic ecosystems are large contributors to global methane (CH4) emissions. Eutrophication significantly enhances CH4-production as it stimulates methanogenesis. Mitigation measures aimed at reducing eutrophication, such as the addition of metal salts to immobilize phosphate (PO43-), are now common practice. However, the effects of such remedies on methanogenic and methanotrophic communities-and therefore on CH4-cycling-remain largely unexplored. Here, we demonstrate that Fe(II)Cl2 addition, used as PO43- binder, differentially affected microbial CH4 cycling-processes in field experiments and batch incubations. In the field experiments, carried out in enclosures in a eutrophic pond, Fe(II)Cl2 application lowered in-situ CH4 emissions by lowering net CH4-production, while sediment aerobic CH4-oxidation rates-as found in batch incubations of sediment from the enclosures-did not differ from control. In Fe(II)Cl2-treated sediments, a decrease in net CH4-production rates could be attributed to the stimulation of iron-dependent anaerobic CH4-oxidation (Fe-AOM). In batch incubations, anaerobic CH4-oxidation and Fe(II)-production started immediately after CH4 addition, indicating Fe-AOM, likely enabled by favorable indigenous iron cycling conditions and the present methanotroph community in the pond sediment. 16S rRNA sequencing data confirmed the presence of anaerobic CH4-oxidizing archaea and both iron-reducing and iron-oxidizing bacteria in the tested sediments. Thus, besides combatting eutrophication, Fe(II)Cl2 application can mitigate CH4 emissions by reducing microbial net CH4-production and stimulating Fe-AOM.
Topics: Methane; Oxidation-Reduction; Ponds; Anaerobiosis; Geologic Sediments; Archaea; Iron; Bacteria; Eutrophication; RNA, Ribosomal, 16S; Ferrous Compounds
PubMed: 38632040
DOI: 10.1093/femsec/fiae061 -
Bioelectrochemistry (Amsterdam,... Aug 2024Addressing the simultaneous removal of multiple coexisting groundwater contaminants poses a significant challenge, primarily because of their different physicochemical...
Addressing the simultaneous removal of multiple coexisting groundwater contaminants poses a significant challenge, primarily because of their different physicochemical properties. Indeed, different chemical compounds may necessitate establishing distinct, and sometimes conflicting, (bio)degradation and/or removal pathways. In this work, we investigated the concomitant anaerobic treatment of toluene and copper in a single-chamber bioelectrochemical cell with a potential difference of 1 V applied between the anode and the cathode. As a result, the electric current generated by the bioelectrocatalytic oxidation of toluene at the anode caused the abiotic reduction and precipitation of copper at the cathode, until the complete removal of both contaminants was achieved. Open circuit potential (OCP) experiments confirmed that the removal of copper and toluene was primarily associated with polarization. Analogously, abiotic experiments, at an applied potential of 1 V, confirmed that neither toluene was oxidized nor copper was reduced in the absence of microbial activity. At the end of each experiment, both electrodes were characterized by means of a comprehensive suite of chemical and microbiological analyses, evidencing a highly selected microbial community competent in the biodegradation of toluene in the anodic biofilm, and a uniform electrodeposition of spherical CuO nanoparticles over the cathode surface.
Topics: Toluene; Copper; Groundwater; Water Pollutants, Chemical; Electrodes; Anaerobiosis; Biodegradation, Environmental; Electrochemical Techniques; Oxidation-Reduction; Biofilms; Water Purification; Bioelectric Energy Sources
PubMed: 38626620
DOI: 10.1016/j.bioelechem.2024.108711 -
The ISME Journal Jan 2024The bacterial species "Candidatus Alkanivorans nitratireducens" was recently demonstrated to mediate nitrate-dependent anaerobic oxidation of short-chain gaseous alkanes...
The bacterial species "Candidatus Alkanivorans nitratireducens" was recently demonstrated to mediate nitrate-dependent anaerobic oxidation of short-chain gaseous alkanes (SCGAs). In previous bioreactor enrichment studies, the species appeared to reduce nitrate in two phases, switching from denitrification to dissimilatory nitrate reduction to ammonium (DNRA) in response to nitrite accumulation. The regulation of this switch or the nature of potential syntrophic partnerships with other microorganisms remains unclear. Here, we describe anaerobic multispecies cultures of bacteria that couple the oxidation of propane and butane to nitrate reduction and the oxidation of ammonium (anammox). Batch tests with 15N-isotope labelling and multi-omic analyses collectively supported a syntrophic partnership between "Ca. A. nitratireducens" and anammox bacteria, with the former species mediating nitrate-driven oxidation of SCGAs, supplying the latter with nitrite for the oxidation of ammonium. The elimination of nitrite accumulation by the anammox substantially increased SCGA and nitrate consumption rates, whereas it suppressed DNRA. Removing ammonium supply led to its eventual production, the accumulation of nitrite, and the upregulation of DNRA gene expression for the abundant "Ca. A. nitratireducens". Increasing the supply of SCGA had a similar effect in promoting DNRA. Our results suggest that "Ca. A. nitratireducens" switches to DNRA to alleviate oxidative stress caused by nitrite accumulation, giving further insight into adaptability and ecology of this microorganism. Our findings also have important implications for the understanding of the fate of nitrogen and SCGAs in anaerobic environments.
Topics: Oxidation-Reduction; Nitrates; Anaerobiosis; Ammonium Compounds; Alkanes; Microbial Consortia; Nitrites; Bioreactors; Bacteria
PubMed: 38624180
DOI: 10.1093/ismejo/wrae063