Dehalogenimonas

This study aims to develop and validate a comprehensive method for assessing ecological disturbances in groundwater ecosystems caused by tetrachloroethylene (PCE) contamination, utilizing flow cytometry (FCM) fingerprint approach. We hypothesized that the ecological disturbance resulting from PCE contamination would exhibit 'press disturbance', persisting over extended periods, and inducing notable phenotypic differences in the microbial community compared to undisturbed groundwater. We collected 42 groundwater samples from industrial district with a history of over twenty years of PCE contamination, along with 56 control groundwater from the national surveillance groundwater system...

1,2-dichloropropane (1,2-DCP) and 1,2,3-trichloropropane (1,2,3-TCP) are hazardous chemicals frequently detected in groundwater near agricultural zones due to their historical use in chlorinated fumigant formulations. In this study, we show that the organohalide-respiring bacterium Dehalogenimonas alkenigignens strain BRE15M can grow during the dihaloelimination of 1,2-DCP and 1,2,3-TCP to propene and allyl chloride, respectively. Our work also provides the first application of dual isotope approach to investigate the anaerobic reductive dechlorination of 1,2-DCP and 1,2,3-TCP...

BACKGROUND: Massive amounts of sewage sludge are generated during biological sewage treatment and are commonly subjected to anaerobic digestion, land application, and landfill disposal. Concurrently, persistent organic pollutants (POPs) are frequently found in sludge treatment and disposal systems, posing significant risks to both human health and wildlife. Metabolically versatile microorganisms originating from sewage sludge are inevitably introduced to sludge treatment and disposal systems, potentially affecting the fate of POPs...

Polybrominated diphenyl ethers (PBDEs) are persistent pollutants that may undergo microbial-mediated debromination in anoxic environments, where diverse anaerobic microbes such as methanogenic archaea co-exist. However, current understanding of the relations between PBDE pollution and methanogenic process is far from complete. To address this knowledge gap, a series of anaerobic soil microcosms were established. BDE-47 (2, 2', 4, 4'-tetrabromodiphenyl ether) was selected as a model pollutant, and electron donors were supplied to stimulate the activity of anaerobes...

A three-dimensional bioelectrochemical system (3D-BES) with both electrocatalytic and biodegradation functions was designed and developed to enhance iodine-containing hormone removal from micro-polluted oligotrophic drinking water sources and to reduce energy consumption. Thyroxine (T4 ) removal efficiency was 99.0% in the 3D-BES amendment with TiO2 @GAC as the particle electrodes, which was 20.5% higher than the total efficiency of single biodegradation (28.7%) plus electrochemical decomposition (49.8%). The high T4 removal efficiency was a result of biochemical synergistic degradation, enhancement of electron transfer and utilization, enrichment of functional microorganisms, and the expression of dehalogenation functional genes...

Microbial dechlorination of polychlorinated biphenyls (PCBs) is limited by the slow growth rate and low activity of dechlorinators. Resuscitation promoting factor (Rpf) of Micrococcus luteus, has been demonstrated to accelerate the enrichment of highly active PCB-dechlorinating cultures. However, it remains unclear whether the addition of Rpf can further improve the dechlorination performance of anaerobic dechlorination cultures. In this study, the effect of Rpf on the performance of TG4, an enriched PCB-dechlorinating culture obtained by Rpf amendment, for reductive dechlorination of four typical PCB congeners (PCBs 101, 118, 138, 180) was evaluated...

Biodegradation is commonly employed for remediating trichloroethene- or toluene-contaminated sites. However, remediation methods using either anaerobic or aerobic degradation are inefficient for dual pollutants. We developed an anaerobic sequencing batch reactor system with intermittent oxygen supply for the codegradation of trichloroethylene and toluene. Our results showed that oxygen inhibited anaerobic dechlorination of trichloroethene, but dechlorination rates remained comparable to that at dissolved oxygen levels of 0...

A strictly anaerobic, organohalide-respiring bacterium, designated strain GPT , was characterized using a polyphasic approach. GPT is Gram-stain-negative, non-spore-forming and non-motile. Cells are irregular cocci ranging between 0.6 and 0.9 µm in diameter. GPT couples growth with the reductive dechlorination of 1,2-dichloroethane, vinyl chloride and all polychlorinated ethenes, except tetrachloroethene, yielding ethene and inorganic chloride as dechlorination end products. H2 and formate serve as electron donors for organohalide respiration in the presence of acetate as carbon source...

Many groundwater aquifers around the world are contaminated with trichloroethene (TCE), which can be harmful to human and ecosystem health. Permeable Reactive Barriers (PRB) are commonly used to remediate TCE-contaminated groundwaters especially when a point source is ill defined. Using biosolids from wastewater treatment plants as a PRB filling material can provide a source of carbon and nutrients for dechlorinating bacterial activity. However, under the anaerobic conditions of the PRB, methanogenesis can also occur which can adversely affect reductive dechlorination...

Micro- and nano-plastics are prevalent in diverse ecosystems, but their impacts on biotransformation of organohalide pollutants and underpinning microbial communities remain poorly understood. Here we investigated the influence of micro- and nano-plastics on microbial reductive dehalogenation at strain and community levels. Generally, microplastics including polyethylene (PE), polystyrene (PS), polylactic acid (PLA), and a weathered microplastic mixture increased dehalogenation rate by 10 - 217% in both the Dehalococcoides isolate and enrichment culture, whereas the effects of polyvinyl chloride (PVC) and a defined microplastic mixture depended on their concentrations and cultures...

Nanoscale zero-valent iron (nZVI) has the potential to degrade a diversity of chlorinated compounds, and it is widely used for remediation of contaminated groundwaters. However, some frequently detected contaminants such as dichloromethane (DCM) and 1,2-dichloroethane (1,2-DCA) have shown nearly no reactivity with nZVI. Here, we tested the feasibility of combining anaerobic dechlorinating bacteria, Dehalobacterium and Dehalogenimonas, and nZVI as a treatment train to detoxify chlorinated methanes (i.e., chloroform-CF- and DCM), and 1,2-DCA...

Brominated organic compounds such as 1,2-dibromoethane (1,2-DBA) are highly toxic groundwater contaminants. Multi-element compound-specific isotope analysis bears the potential to elucidate the biodegradation pathways of 1,2-DBA in the environment, which is crucial information to assess its fate in contaminated sites. This study investigates for the first time dual C-Br isotope fractionation during in vivo biodegradation of 1,2-DBA by two anaerobic enrichment cultures containing organohalide-respiring bacteria (i...

1,2,3-trichloropropane (TCP), a refractory contaminant, can be reductive dehalogenated to allyl chloride (AC) by microorganisms, which has been shown a potential in situ bioremediation (ISB) strategy for TCP remediation in groundwater. In practice, however, it is hard to monitor the bioreduction extent because the TCP concentrations may also be decreased by non-biodegradation processes. Compound specific isotope analysis (CSIA) can be promising in determining the extent of degradation by quantifying the isotope enrichment factors (ε) of relevant degradation mechanisms...

The Cape fynbos biome in South Africa is home to highly diverse and endemic shrub legumes, which include species of Aspalathus , Polhillia , Wiborgia and Wiborgiella . These species play a significant role in improving soil fertility due to their ability to fix N2 . However, information regarding their microbiome is still unknown. Using the 16S rRNA Miseq illumina sequencing, this study assessed the bacterial community structure associated with the rhizospheres of Polhillia pallens , Polhillia brevicalyx , Wiborgia obcordata , Wiborgia sericea and Wiborgiella sessilifolia growing at different locations during the wet and dry seasons in the Cape fynbos...

Organohalide pollutants are prevalent in the environment, causing harms to wildlife and human. Organohalide-respiring bacteria (OHRB) could detoxify these pollutants in anaerobic environments, but the most competent OHRB (i.e., Dehalococcoides) is susceptible to oxygen. This study reports exceptional resistance and resilience of sewage sludge microbial communities to oxygen stress for attenuation of structurally distinct organohalide pollutants, including tetrachloroethene, tetrabromobisphenol A, and polybrominated diphenyl ethers...

Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile, TePN) is one of the most widely used fungicides all over the world. Its major environmental transformation product 4-hydroxy-chlorothalonil (4-hydroxy-2,5,6-trichloroisophthalonitrile, 4-OH-TPN) is more persistent, mobile, and toxic and is frequently detected at a higher concentration in various habitats compared to its parent compound TePN. Further microbial transformation of 4-OH-TPN has never been reported. In this study, we demonstrated that 4-OH-TPN underwent complete microbial reductive dehalogenation to 4-hydroxy-isophthalonitrile via 4-hydroxy-dichloroisophthalonitrile and 4-hydroxy-monochloroisophthalonitrile...

Diclofenac (DCF) is a pharmaceutically active contaminant frequently found in aquatic ecosystems. The transformation pathways and microbiology involved in the biodegradation of DCF, particularly under anoxic conditions, remain poorly understood. Here, we demonstrated microbially mediated reductive dechlorination of DCF in anaerobic enrichment culture derived from contaminated river sediment. Over 90% of the initial 76.7 ± 3.6 μM DCF was dechlorinated at a maximum rate of 1.8 ± 0.3 μM day-1 during a 160 days' incubation...

Natural attenuation of contaminants has been increasingly applied as a strategy to manage the retired pesticide manufacturing sites due to the increasing restrictions on the reuse of contaminated sites in China. However, the influencing factors to enhance natural attenuation for chlorinated hydrocarbons in retired pesticide sites were not well studied. In this paper, monitoring of pollutants, environmental factors and microbial community was conducted from 2016 to 2021 in a retired pesticide site in Jiangsu Province undergoing natural attenuation, where the groundwater was severely contaminated with chlorinated hydrocarbons...

Bioaugmentation is a promising strategy for enhancing trichloroethylene (TCE) degradation in fractured rock. However, slow or incomplete biodegradation can lead to stalling at degradation byproducts such as 1,2-dichloroethene (cis-DCE) and vinyl chloride (VC). Over the course of 7 years, we examined the response of groundwater microbial populations in a bioaugmentation test where an emulsified vegetable oil solution (EOS®) and a dechlorinating consortium (KB-1®), containing the established dechlorinator Dehalococcoides, were injected into a TCE-contaminated fractured rock aquifer...

Widespread polybrominated diphenyl ethers (PBDEs) contamination poses risks to human health and ecosystems. Bioremediation is widely considered to be a less ecologically disruptive strategy for remediation of organohalide contamination, but bioremediation of PBDE-contaminated sites is limited by a lack of knowledge about PBDE-dehalogenating microbial populations. Here we report anaerobic PBDE debromination in microcosms established from geographically distinct e-waste recycling sites. Complete debromination of a penta-BDE mixture to diphenyl ether was detected in 16 of 24 investigated microcosms; further enrichment of these 16 microcosms implicated microbial populations belonging to the bacterial genera Dehalococcoides, Dehalogenimonas, and Dehalobacter in PBDE debromination...