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The decay and distribution of bacterial pathogens in water is an important information for the health risk assessment to guide water safety management, and suspended algae might affect bacterial pathogens in water. This study established microcosms to investigate the effects of algae-related factors on the representative indicators and opportunistic pathogen species in water. We found that suspended algae increased the persistence of targeted species by 1-2 orders of magnitude of concentrations compared to microcosms without algae; and the effect of algae on microbial survival was affected by water nutrient levels (i.e., carbon, nitrogen and phosphorus), as the increased microbial persistence were correlated to the increased algae concentrations with more nutrient supplies. Moreover, decay and distribution profiles of representative species were determined. The three opportunistic pathogen species (Pseudomonas aeruginosa, Aeromonas hydrophila and Staphylococcus aureus) showed lower decay rates (0.82–0.98/day, 0.76–0.98/day, 0.63–0.87/day) largely affected by algae-related factors, while the enteric species (Escherichia coli and Enterococcus faecalis) had higher decay rates (0.94–1.31/day, 0.89–1.21/day) with little association with algae, indicating the propensity for attachment to algae is an important parameter in microbial fate. Together results suggest suspended algae played an evident role in the decay and distribution of bacterial pathogens, providing important implications regarding microbial safety in recreational water. [Display omitted] [ABSTRACT FROM AUTHOR]

Summary: Polycyclic aromatic hydrocarbons (PAHs) are widespread and harmful contaminants and are more persistent under anaerobic conditions. The bioremediation of PAHs in anaerobic zones has been enhanced by treating the contamination with nitrate, which is thermodynamically favourable, cost‐effective, and highly soluble. However, anaerobic PAHs biotransformation processes that employ nitrate as an electron acceptor have not been fully explored. In this study, we investigated the anaerobic biotransformation of PAHs by strain PheN1, a newly isolated phenanthrene‐degrading denitrifier, using phenanthrene as a model compound. PheN1 is phylogenetically closely related to Achromobacter denitrificans and reduces nitrate to nitrite (not N2) during the anaerobic phenanthrene degradation process. Phenanthrene biotransformation processes were detected using gas chromatography–mass spectrometry and were further examined by reverse transcription‐quantitative PCR and genome analyses. Carboxylation and methylation were both found to be the initial steps in the phenanthrene degradation process. Downstream biotransformation processed benzene compounds and cyclohexane derivatives. This study describes the isolation of an anaerobic phenanthrene‐degrading bacterium along with the pure‐culture evidence of phenanthrene biotransformation processes with nitrate as an electron acceptor. The findings in this study can improve our understanding of anaerobic PAHs biodegradation processes and guide PAHs bioremediation by adding nitrate to anaerobic environments. [ABSTRACT FROM AUTHOR]

Recently, the potential of magnetite facilitating anaerobic methanogenic degradation of organic matters in natural or engineered microbial ecosystems has been reported. Here, we evaluated the effects of magnetite powder (<5 μm) and nanoFe 3 O 4 powder (50–100 nm) on phenanthrene methanogenic degradation by a mixed consortium enriched from petroleum contaminated soil. The results showed that complete phenanthrene degradation in our enrichment cultures required a syntrophic cooperation between degrading bacteria and methanogens. The addition of magnetite and nanoFe 3 O 4 did not increase the relative abundance of methanogens, but improved phenanthrene degradation rates by 25.92% and 25.99%, and enhanced methane production rates by 21.5% and 20.1%, respectively. Further studies showed that the addition of magnetite and nanoFe 3 O 4 improved electron transporting system (ETS) activities in the enrichment cultures, possibly through serving as electron conduits to facilitate DIET between syntrophic bacteria and methanogens. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) is a novel wastewater treatment process. The intrinsic nature of anammox bacteria makes their traditional isolation from a consortium impossible. This study presents a detailed assessment of different pretreatments for percoll density gradient centrifugation (PDGC) to purify anammox bacteria and proposes that the extraction of extracellular polymeric substances (EPS) could significantly increase the purification performance. The results demonstrate that both EPS extraction using cation exchange resin for 2 h and mild ultrasound at an optimal power of 7.2 kJ were suitable pretreatments to increase the purification efficiency in comparison to PDGC performed directly from an original consortium (optimal conditions identified as 8000 rpm, 30 min). Importantly, the implementation of EPS extraction before ultrasound was verified to have the capacity to further increase the purification efficiency up to 95%, which demonstrates the prominent effects of EPS extraction on the PDGC performance. Compared to the previous report, EPS extraction was applied instead of the first centrifugation prior to PDGC to remove large flocs, which correspondingly increased the purified amounts. To clarify the involved mechanism, the bacteria aggregating behaviors before and after EPS extraction over time were visually tracked using a particle size analyzer. The results of this study help to obtain large amounts of anammox bacteria and elucidate the anammox characteristics and communities in both natural and engineered systems. [ABSTRACT FROM AUTHOR]

PAHs have been widely detected to accumulate in saline and hypersaline environments. Moderately halophilic microbes are considered the most suitable player for the elimination of PAHs in such environments. In this study, consortium 5H was enriched under 5% salinity and completely degraded phenanthrene in 5 days. By high-throughput sequencing, consortium 5H was identified as being mainly composed of Methylophaga , Marinobacter and Thalassospira. Combined with the investigation of intermediates and enzymatic activities, the degradation pathway of consortium 5H on phenanthrene was proposed. Consortium 5H was identified as having the ability to tolerate a wide range of salinities (1%–10%) and initial PAH concentrations (50 mg/L to 400 mg/L). It was also able to function under neutral to weak alkaline conditions (pH from 6 to 9) and the phytotoxicity of the produced intermediates showed no significant difference with distilled water. Furthermore, the metagenome of consortium 5H was measured and analyzed, which showed a great abundance of catabolic genes contained in consortium 5H. This study expanded the knowledge of PAH-degradation under hypersaline environments and consortium 5H was proposed to have good potential for the elimination of PAH pollution in saline/hypersaline environments. [Display omitted] • Consortium 5H is able to degrade PAHs under a wide range of salinity. • Eighty-four percent of phenanthrene has been degraded in 2 days after incubation. • PAH-degrading pathway has been proposed by GC-MS, metagenome and enzyme assay. • A large number of functional genes are identified in the metagenome information. • The intermediate metabolites in PHE-degrading process shows weak biotoxicity. [ABSTRACT FROM AUTHOR]

Highlights: [•] We investigated influence of Ca2+ on the damaged anammox consortium restoration. [•] Restoration was faster with increasing Ca2+ dosage in range of 0.02–0.5mM. [•] A strong correlation between Ca2+ dosage and steady-state intracellular free Ca2+. [•] High steady-state intracellular free Ca2+ favors anammox consortium restoration. [Copyright &y& Elsevier]

The ubiquitous environmental contaminants, polycyclic aromatic hydrocarbons (PAHs), can be aerobically biodegraded. Strategies for biodegradation of PAHs are needed for the persisted character of it in anoxic environments. In current study, we obtained a highly enriched anaerobic, PAHs-degrading co-culture DYM1, from petroleum-polluted soil. DYM1 significantly degrades a range of PAHs in 4 days without supplementary terminal electron acceptors. Co-culture DYM1 is consists of two microorganisms (a degrading bacterium Paracoccus sp. strain PheM1 and an aceticlastic methanogen Methanosaeta concilii.) that utilize different carbon sources in a syntrophic metabolic process of phenanthrene. About 93% of phenanthrene (104.5 μM) has been removed under methanogenic conditions after incubation with co-culture DYM1 for 4 d, and produced 33.68 μmol CH 4. Carboxylation, which is catalyzed by UbiD-like carboxylase, was proposed as the initial steps of methanogenic phenanthrene-degrading pathway based upon the detection of 2-phenanthroic acid and 4-phenanthrene acid. Reduction and hydration of the benzene rings were followed by the initial reaction. Hydrated phenanthroic acid metabolites were newly detected and characterized under anaerobic conditions. Anaerobic degradation of phenanthrene without terminal electron acceptor addition not only sheds light on a poorly understood and environmentally relevant biological process, but also supply a novel approach to recover the energy of toxic pollutant in forms of methane. [Display omitted] • DYM1 was a newly obtained methanogenic PAHs-degrading culture. • DYM1 consists of a degrading bacterium and an aceticlastic methanogen. • Phenanthrene was anaerobically removed without terminal electron acceptors. • Methanogenic biotransformation processes of phenanthrene were firstly explored. • Hydrated phenanthroic acid metabolites were newly detected and characterized. [ABSTRACT FROM AUTHOR]

The study of biodegradation of polycyclic aromatic hydrocarbons (PAHs) with metal ions as electron acceptors is still in its infancy. Here, a pure culture of PheF2 sharing 99.79% 16S rRNA-sequence similarity with Trichococcus alkaliphilus , which was recently reported to degrade PAHs, was isolated and found to degrade PAHs with Fe (III) or O 2 reduction. Phenanthrene was selected as a model of PAH to study the biodegradation process by PheF2 with Fe (III) or O 2 as an electron acceptor. PheF2 exhibited nearly 100%, 37.1%, and 28.5% anaerobic biodegradation of phenanthrene at initial concentrations of 280.7 μM, 280.6 μM, and 281.3 μM, respectively, within 10 days under anaerobic conditions with XAD-7 as a carrier, heptamethylnonane (HMN) as a solution, and nothing, respectively. PheF2 could degrade nearly 100% of the initial phenanthrene concentration of 283.4 μM under aerobic conditions within three days. The initial step of phenanthrene biodegradation by PheF2 involved carboxylation and dioxygenation under anaerobic and aerobic conditions, respectively. The biotransformation processes of phenanthrene degradation by PheF2 with Fe(III) or O 2 as an electron acceptor were explored by metabolite and genome analysis. These findings provide an important theoretical support for evaluation of PAHs fate and for PAHs pollution control or remediation in anaerobic and aerobic environments. Unlabelled Image • PheF2 was newly reported in aerobic and anaerobic phenanthrene (PHE) biodegradation. • XAD-7 carrier can effectively promote anaerobic PHE biodegradation rate. • Anaerobic PHE biodegradation processes were proposed coupled with Fe(III) reduction. [ABSTRACT FROM AUTHOR]