Phage phylogeny, molecular signaling, and auxiliary antimicrobial resistance in aerobic and anaerobic membrane bioreactors.

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.

Antibiotic resistance genes fate during food waste management - Comparison between thermal treatment, hyperthermophilic composting, and anaerobic membrane bioreactor.

The fate of eight different antibiotic resistance genes (ARGs) in food waste (sul1, sul2, tetO, tetW, ermF, ermB, ampC, oxa-1), intI1, and rpoB were monitored during thermal treatment (pyrolysis and incineration), hyperthermophilic composting, and anaerobic membrane bioreactor (AnMBR) treatment. ARGs in food waste ranged from 2.9 × 106 to 3.5 × 109 copies/kg with ampC being the least abundant and sul1 being the most abundant. Thermal treatment achieved removal below detection limits of all ARGs. Only two ARGs (sul1 and ampC) persisted in hyperthermophilic composting. While all genes except for ermB decreased in the AnMBR effluent relative to the food waste feed, sul1 remained at relatively high abundance. Biosolids on the contrary, accumulated tetO, ampC and sul2 in all tested operating conditions. Thermal treatment, despite limited resource recovery, provides the most effective mitigation of ARG risk in food waste.

Impact of engineered nanoparticles on the fate of antibiotic resistance genes in wastewater and receiving environments: A comprehensive review.

Nanoparticles (NPs) and antibiotic resistance elements are ubiquitous in wastewater and consequently, in receiving environments. Sub-lethal levels of engineered NPs potentially result in a selective pressure on antibiotic resistance gene (ARG) propagation in wastewater treatment plants. Conversely, emergent NPs are being designed to naturally attenuate ARGs based on special physical and electrochemical properties, which could alleviate dissemination of ARGs to the environment. The complex interactions between NPs and antibiotic resistance elements have heightened interest in elucidating the potential positive and negative implications. This review focuses on the properties of NPs and ARGs and how their interactions could increase or decrease antibiotic resistance at wastewater treatment plants and in receiving environments. Further, the potential for sub-lethal level NPs to facilitate horizontal gene transfer of ARGs and increase mutagenesis rates, which adds a layer of complexity to combatting antibiotic resistance associated with wastewater management, is discussed. Notably, the literature revealed that sub-lethal exposure of engineered NPs may facilitate conjugative transfer of ARGs by increasing cell membrane permeability. The enhanced permeability is a result of direct damage via NP attachment and indirect damage by generating reactive oxygen species (ROS) and causing genetic changes relevant to conjugation. Finally, current knowledge gaps and future research directions (e.g., deciphering the fate of NPs in the environment and examining the long-term cytotoxicity of NPs) are identified for this emerging field.

Antibiotic transformation in an anaerobic membrane bioreactor linked to membrane biofilm microbial activity.

Although extensive research to date has focused on enhancing removal rates of antibiotics from municipal wastewaters, the transformation products formed by anaerobic treatment processes remain understudied. The present work aims to examine the possible roles that the different microbial communities of an anaerobic membrane bioreactor (AnMBR) play in the transformation of antibiotics during wastewater treatment. As part of this work, sulfamethoxazole, erythromycin, and ampicillin were added in separate stages to the influent of the AnMBR at incremental concentrations of 10, 50, and 250 µg/L each. Antibiotic-specific transformation products detected during each stage, as identified by high resolution LC-MS, are reported herein. Results suggest that both isoxazole (sulfamethoxazole) and ß-lactam (ampicillin) ring opening could be facilitated by the AnMBR's bioprocess. Microbial community analysis results indicated that relative activity of the system's suspended biomass consistently shifted towards syntrophic groups throughout the duration of the experiment. Notable differences were also observed between the suspended biomass and the AnMBR's membrane biofilms. Membrane-attached biofilm communities showed high relative activities of several specific methanogenic (Methanothrix and Methanomethylovorans), syntrophic (Syntrophaceae), and sulfate-reducing (Desulfomonile) groups. Such groups have been previously identified as involved in the formation of the antibiotic degradation products observed in the effluent of the AnMBR. The activity of these communities within the biofilms likely confers certain advantages that aid in the biotransformation of the antibiotics tested.

Unlocking capacities of viral genomics for the COVID-19 pandemic response.

More than any other infectious disease epidemic, the COVID-19 pandemic has been characterized by the generation of large volumes of viral genomic data at an incredible pace due to recent advances in high-throughput sequencing technologies, the rapid global spread of SARS-CoV-2, and its persistent threat to public health. However, distinguishing the most epidemiologically relevant information encoded in these vast amounts of data requires substantial effort across the research and public health communities. Studies of SARS-CoV-2 genomes have been critical in tracking the spread of variants and understanding its epidemic dynamics, and may prove crucial for controlling future epidemics and alleviating significant public health burdens. Together, genomic data and bioinformatics methods enable broad-scale investigations of the spread of SARS-CoV-2 at the local, national, and global scales and allow researchers the ability to efficiently track the emergence of novel variants, reconstruct epidemic dynamics, and provide important insights into drug and vaccine development and disease control. Here, we discuss the tremendous opportunities that genomics offers to unlock the effective use of SARS-CoV-2 genomic data for efficient public health surveillance and guiding timely responses to COVID-19.

Investigation of Fats, Oils, and Grease Co-digestion With Food Waste in Anaerobic Membrane Bioreactors and the Associated Microbial Community Using MinION Sequencing.

Co-digestion of fats, oils, and grease (FOG) with food waste (FW) can improve the energy recovery in anaerobic membrane bioreactors (AnMBRs). Here, we investigated the effect of co-digestion of FW and FOG in AnMBRs at fat mass loading of 0.5, 0.75, and 1.0 kg m-3 day-1 with a constant organic loading rate of 5.0 gCOD L-1 day-1 in both a single-phase (SP) and two-phase (TP) configuration. A separate mono-digestion of FW at an identical organic loading rate was used as the benchmark. During co-digestion, higher daily biogas production, ranging from 4.0 to 12.0%, was observed in the two-phase methane phase (TP-MP) reactor compared to the SP reactor, but the difference was statistically insignificant (p > 0.05) due to the high variability in daily biogas production. However, the co-digestion of FW with FOG at 1.0 kg m-3 day-1 fat loading rate significantly (p < 0.05) improved daily biogas production in both the SP (11.0%) and TP (13.0%) reactors compared to the mono-digestion of FW. Microbial community analyses using cDNA-based MinION sequencing of weekly biomass samples from the AnMBRs revealed the prevalence of Lactobacillus (92.2-95.7% relative activity) and Anaerolineaceae (13.3-57.5% relative activity), which are known as fermenters and fatty acid degraders. Syntrophic fatty acid oxidizers were mostly present in the SP and TP-MP reactors, possibly because of the low pH and short solid retention time (SRT) in the acid phase digesters. A greater abundance of the mcrA gene copies (and methanogens) was observed in the SP and MP reactors compared to the acid-phase (AP) reactors. This study demonstrates that FW and FOG can be effectively co-digested in AnMBRs and is expected to inform full-scale decisions on the optimum fat loading rate.

Out-of-Hospital Cardiac Arrest in London during the COVID-19 pandemic.

AIM: There is an emerging potential link between the COVID-19 pandemic and incidence and outcomes from out-of-hospital cardiac arrest (OHCA). We aimed to describe the incidence, characteristics and outcomes from OHCA in London, UK during the first wave of the pandemic. METHODS: We examined data for all OHCA patients attended by the London Ambulance Service from 1st March to 30th April 2020 and compared our findings to the previous year. We also compared OHCA characteristics and short-term outcomes for those suspected or confirmed to have COVID-19 with those who were not. Additionally, we investigated the relationship between daily COVID-19 cases and OHCA incidents. RESULTS: We observed an 81% increase in OHCAs during the pandemic, and a strong correlation between the daily number of COVID-19 cases and OHCA incidents (r = 0.828, p < 0.001). We report an increase in OHCA occurring in a private location (92.9% vs 85.5%, p < 0.001) and an increased bystander CPR (63.3% vs 52.6%, p < 0.001) during the pandemic, as well as fewer resuscitation attempts (36.4% vs 39.6%, p = 0.03) and longer EMS response times (9.3 vs 7.2 min, p < 0.001). Survival at 30 days post-arrest was poorer during the pandemic (4.4% vs 10.6%, p < 0.001) and amongst patients where COVID-19 was considered likely (1.0% vs 6.3%, p < 0.001). CONCLUSIONS: During the first wave of the COVID-19 pandemic in London, we saw a dramatic rise in the incidence of OHCA, accompanied by a significant reduction in survival. The pattern of increased incidence and mortality closely reflected the rise in confirmed COVID-19 infections in the city.

Solid waste: An overlooked source of microplastics to the environment.

Microplastics pollution is one of the most pressing environmental problems of the 21st century. While microplastics are pervasive throughout various environmental compartments, research to date has primarily focused on marine systems. Land-based microplastics sources (e.g., solid waste) have received comparatively little attention, although they account for the main flow of microplastics into aquatic environments. Solid waste microplastics sources primarily include landfill refuse, sludge, and food waste. Microplastics in these waste streams can be associated with various micropollutants that can have deleterious impacts on ecosystem health as they enter the food chain. Thus, understanding the occurrence, fate, and degradation pathways of solid waste microplastics is essential to develop comprehensive control and mitigation strategies. This study critically reviewed these key aspects of microplastics in municipal solid waste landfill refuse, sewage sludge, and food waste, and identified the interconnections of these components in the proliferation of microplastics to the environment. Additionally, microplastics related laws and regulations and their relevance to solid waste microplastics mitigation are discussed.

Intracellular versus extracellular antibiotic resistance genes in the environment: Prevalence, horizontal transfer, and mitigation strategies.

Antibiotic resistance genes (ARGs) are present as both intracellular and extracellular fractions of DNA in the environment. Due to the poor yield of extracellular DNA in conventional extraction methods, previous studies have mainly focused on intracellular ARGs (iARGs). In this review, we evaluate the prevalence/persistence and horizontal transfer of iARGs and extracellular ARGs (eARGs) in different environments, and then explore advanced mitigation strategies in wastewater treatment plants (WWTPs) for preventing the spread of antibiotic resistance in the environment. Although iARGs are the main fraction of ARGs in nutrient-rich environments, eARGs are predominant in receiving aquatic environments. In such environments, natural transformation of eARGs occurs with a comparable frequency to conjugation of iARGs. Further, eARGs can be adsorbed by soil and sediments particles, protected from DNase degradation, and consequently persist longer than iARGs. Collectively, these characteristics emphasize the crucial role of eARGs in the spread of antibiotic resistance in the environment. Fate of iARGs and eARGs through advanced treatment technologies (disinfection and membrane filtration) indicates that different mitigation strategies may be required for each ARG fraction to be significantly removed. Finally, comprehensive risk assessment is needed to evaluate/compare the effect of iARGs versus eARGs in the environment.

Membrane Fouling Inversely Impacts Intracellular and Extracellular Antibiotic Resistance Gene Abundances in the Effluent of an Anaerobic Membrane Bioreactor.

Anaerobic membrane bioreactors (AnMBRs) can significantly reduce the release of antibiotic resistance elements to the environment. The purpose of this study was to elucidate the role of membrane fouling layers (biofilms) in mitigating the release of intracellular and extracellular antibiotic resistance genes (iARGs and eARGs) from an AnMBR. The AnMBR was equipped with three membrane modules, each exhibiting a different level of fouling. Results showed that the absolute abundance of ARGs decreased gradually in the suspended biomass during operation of the AnMBR. Normalized abundances of targeted ARGs and intI1 were found to be significantly higher in the fouling layers compared to the suspended biomass, implying adsorption or an increased potential for horizontal gene transfer of ARGs in the biofilm. Effluent ARG data revealed that the highly fouled (HF) membrane significantly reduced the absolute abundance of eARGs. However, the HF membrane effluent concomitantly had the highest absolute abundance of iARGs. Nevertheless, total ARG abundance (sum of iARG and eARG) in the effluent of the AnMBR was not impacted by the extent of fouling. These results suggest a need for a combination of different treatment technologies to effectively prevent antibiotic resistance proliferation associated with these two ARG fractions.

Performance and microbial ecology of methane-driven microbial fuel cells at temperatures ranging from 25 to 5 °C.

The effluent of mainstream anaerobic processes is saturated with dissolved methane, representing a lost energy source and potent greenhouse gas emission if left unmanaged. This study investigated the impact of operational temperature on methane-driven microbial fuel cells (MFCs) designed for continuous operation to mitigate dissolved methane emissions in anaerobic effluents. Two bench-scale, single-chamber MFCs were operated sequentially at 25, 20, 15, 10 and 5 °C. Voltage production from both MFCs ranged from approximately 0.463 to 0.512 V over 1 kΩ resistance at temperatures ≥15 °C, but abruptly dropped as temperature decreased to 10 and 5 °C, averaging just 0.156 and 0.190 V for the replicate systems. Dissolved methane removal efficiency remained relatively stable across all operational temperatures, ranging from 53.0% to 63.6%. High-throughput sequencing of 16S rRNA genes and reverse transcription quantitative polymerase chain reaction indicated distinct distribution of methanotrophs (e.g., Methylomonas) and exoelectrogens (e.g., Geobacter) on the cathode and anode, respectively. Spearman's rank correlation suggested that an indirect interaction between methanotrophs and exoelectrogens via fermentative bacteria (e.g., Acetobacterium) may play a role in system function. Notably, diversity of the anode microbial community was positively correlated with both voltage production and Coulombic efficiency, suggesting overall diversity, as opposed to abundance or activity of exoelectrogens, was the primary factor governing performance at varying temperatures.

Two-Phase Improves Performance of Anaerobic Membrane Bioreactor Treatment of Food Waste at High Organic Loading Rates.

Anaerobic membrane bioreactors (AnMBRs) are in use at the full-scale for energy recovery from food waste (FW). In this study, the potential for two-phase (acid/gas) AnMBR treatment of FW was investigated as a strategy to increase microbial diversity, thereby improving performance. Two bench-scale AnMBRs were operated in single-phase (SP) and two-phase (TP) mode across incremental increases in organic loading rate (OLR) from 2.5 to 15 g total chemical oxygen demand (COD) L·d-1. The TP acid-phase (TP-AP) enriched total VFAs by 3-fold compared to influent FW and harbored a distinct microbial community enriched in fermenters that thrived in the low pH environment. The TP methane phase (TP-MP) showed increased methane production and resilience relative to SP as OLR increased from 3.5 to 10 g COD L·d-1. SP showed signs of inhibition (i.e., rapid decrease in methane production per OLR) at 10 g COD L·d-1, whereas both systems were inhibited at 15 g COD L·d-1. At 10 g COD L·d-1, where the highest difference in performance was observed (20.3% increase in methane production), activity of syntrophic bacteria in TP-MP was double that of SP. Our results indicate that AnMBRs in TP mode could effectively treat FW at OLRs up to 10 g COD·L day-1 by improving hydrolysis rates, microbial diversity, and syntroph activity, and enriching resistant communities to high OLRs relative to AnMBRs in SP mode.

Perspectives on the fate of micropollutants in mainstream anaerobic wastewater treatment.

Mainstream anaerobic treatment technologies are a viable alternative to conventional aerobic treatment to recover resources and improve process sustainability. However, resource recovery efforts must be coordinated with efforts to abate environmental risks associated with micropollutants (e.g. pharmaceuticals). The microbial and physical mechanisms of micropollutant removal in mainstream anaerobic systems remain poorly understood. Recent work suggests that anaerobic systems may enhance removal of compounds typically persistent during aerobic wastewater treatment, such as sulfamethoxazole, trimethoprim, clozapine, triclocarban, and amitriptyline. Process enhancements such as using sorptive materials or multi-stage treatment may further improve system-wide micropollutant removal. A better understanding of removal mechanisms in mainstream anaerobic treatment could reduce environmental pervasiveness of recalcitrant contaminants, while concomitantly advancing resource recovery.

Evaluating Antibiotic Resistance Gene Correlations with Antibiotic Exposure Conditions in Anaerobic Membrane Bioreactors.

Anaerobic membrane bioreactors (AnMBRs) are an emerging technology with potential to improve energy efficiency and effluent reuse in mainstream wastewater treatment. However, their contribution to the proliferation of contaminants of emerging concern, such as antibiotic resistance genes (ARGs), remains largely unknown. The purpose of this study was to determine the effect of select influent antibiotics at varying concentrations on the presence and abundance of ARGs in an AnMBR system and its effluent. Quantification of targeted ARGs revealed distinct profiles in biomass and effluent, with genes conferring resistance to different antibiotic classes dominating in biomass (macrolides) and effluent (sulfonamides). Effluent sul1 gene abundance was strongly correlated with abundance of intl1, signifying the potential importance of mobile genetic elements in ARG release from AnMBR systems. The addition of specific antibiotics also affected normalized abundances of their related ARGs, exemplifying the potential impact of selective pressures at both low (10 µg/L) and high (250 µg/L) influent antibiotic concentrations.

Bayesian adaptive bandit-based designs using the Gittins index for multi-armed trials with normally distributed endpoints.

Adaptive designs for multi-armed clinical trials have become increasingly popular recently because of their potential to shorten development times and to increase patient response. However, developing response-adaptive designs that offer patient-benefit while ensuring the resulting trial provides a statistically rigorous and unbiased comparison of the different treatments included is highly challenging. In this paper, the theory of Multi-Armed Bandit Problems is used to define near optimal adaptive designs in the context of a clinical trial with a normally distributed endpoint with known variance. We report the operating characteristics (type I error, power, bias) and patient-benefit of these approaches and alternative designs using simulation studies based on an ongoing trial. These results are then compared to those recently published in the context of Bernoulli endpoints. Many limitations and advantages are similar in both cases but there are also important differences, specially with respect to type I error control. This paper proposes a simulation-based testing procedure to correct for the observed type I error inflation that bandit-based and adaptive rules can induce.

Effects of changes in temperature on treatment performance and energy recovery at mainstream anaerobic ceramic membrane bioreactor for food waste recycling wastewater treatment.

An anaerobic ceramic membrane bioreactor (AnCMBR) has been attracted as an alternative technology to co-manage various organic substrates. This AnCMBR study investigated process performance and microbial community structure at decreasing temperatures to evaluate the potential of AnCMBR treatment for co-managing domestic wastewater (DWW) and food waste-recycling wastewater (FRW). As a result, the water flux (≥6.9 LMH) and organic removal efficiency (≥98.0%) were maintained above 25 °C. The trend of methane production in the AnCMBR was similar except for at 15 °C. At 15 °C, the archaeal community structure did not shifted, whereas the bacterial community structure was changed. Various major archaeal species were identified as the mesophilic methanogens which unable to grow at 15 °C. Our results suggest that the AnCMBR can be applied to co-manage DWW and FRW above 20 °C. Future improvements including psychrophilic methanogen inoculation and process optimization would make co-manage DWW and FRW at lower temperature climates.

Inhibition of anaerobic digestion processes: Applications of molecular tools.

Inhibition of anaerobic digestion (AD) due to perturbation caused by substrate composition and/or operating conditions can significantly reduce performance. Such perturbations could be limited by elucidating microbial community response to inhibitors and devising strategies to increase community resilience. To this end, advanced molecular methods are increasingly being applied to study the AD microbiome, a diverse community of microbial populations with complex interactions. This literature review of AD inhibition studies indicates that inhibitory concentrations are highly variable, likely stemming from differences in community structure or activity profile and previous exposure to inhibitors. More recent molecular methods such as 'omics' tools, substrate mapping, and real-time sequencing are helping to unravel the complexity of AD inhibition by elucidating physiological and ecological significance of key microbial populations. The AD community must strive towards developing predictive abilities to avoid system failure (e.g., real-time tracking of an indicator species) to improve resilience of AD systems.

Elucidating microbial community adaptation to anaerobic co-digestion of fats, oils, and grease and food waste.

Despite growing interest in co-digestion and demonstrated process improvements (e.g., enhanced stability and biogas production), few studies have evaluated how co-digestion impacts the anaerobic digestion (AD) microbiome. Three sequential bench-scale respirometry experiments were conducted at thermophilic temperature (50 °C) with various combinations of primary sludge (PS); thickened waste activated sludge (TWAS); fats, oils, and grease (FOG); and food waste (FW). Two additional runs were then performed to evaluate microbial inhibition at higher organic fractions of FOG (30-60% volatile solids loading (VSL; v/v)). Co-digestion of PS, TWAS, FOG, and FW resulted in a 26% increase in methane production relative to digestion of PS and TWAS. A substantial lag time was observed in biogas production for vessels with FOG addition that decreased by more than half in later runs, likely due to adaptation of the microbial community. 30% FOG with 10% FW showed the highest increase in methane production, increasing 53% compared to digestion of PS and TWAS. FOG addition above 50% VSL was found to be inhibitory with and without FW addition and resulted in volatile fatty acid (VFA) accumulation. Methane production was linked with high relative activity and abundance of syntrophic fatty-acid oxidizers alongside hydrogenotrophic methanogens, signaling the importance of interspecies interactions in AD. Specifically, relative activity of Syntrophomonas was significantly correlated with methane production. Further, methane production increased over subsequent runs along with methyl coenzyme M reductase (mcrA) gene expression, a functional gene in methanogens, suggesting temporal adaptation of the microbial community to co-digestion substrate mixtures. The study demonstrated the benefits of co-digestion in terms of performance enhancement and enrichment of key active microbial populations.

Co-management of domestic wastewater and food waste: A life cycle comparison of alternative food waste diversion strategies.

Food waste is increasingly viewed as a resource that should be diverted from landfills. This study used life cycle assessment to compare co-management of food waste and domestic wastewater using anaerobic membrane bioreactor (AnMBR) against conventional activated sludge (CAS) and high rate activated sludge (HRAS) with three disposal options for food waste: landfilling (LF), anaerobic digestion (AD), and composting (CP). Based on the net energy balance (NEB), AnMBR and HRAS/AD were the most attractive scenarios due to cogeneration of produced biogas. However, cogeneration negatively impacted carcinogenics, non-carcinogenics, and ozone depletion, illustrating unavoidable tradeoffs between energy recovery from biogas and environmental impacts. Fugitive emissions of methane severely increased global warming impacts of all scenarios except HRAS/AD with AnMBR particularly affected by effluent dissolved methane emissions. AnMBR was also most sensitive to food waste diversion participation, with 40% diversion necessary to achieve a positive NEB at the current state of development.