Hexachlorocyclohexanes (HCH) isomers and their transformation products, such as chlorobenzenes (ClB), generate severe and persistent environmental problems at many sites worldwide. The Wetland technology employing oxidation-reduction, biosorption, biodegradation and phytoremediation methods can sufficiently treat HCH-contaminated water. The treatment process is inherently natural and requires no supplementary chemicals or energy. The prototype with a capacity of 3 L/s was installed at Hajek quarry spoil heap (CZ), to optimize the technology on a full scale. The system is fed by drainage water with an average concentration of HCH 129 μg/L, ClB 640 μg/L and chlorophenols (ClPh) of 16 μg/L. The system was tested in two years of operation, regularly monitored for HCH, ClB and ClPh, and maintained to improve its efficiency. The assessment was not only for environmental effects but also for socio and economic indicators. During the operation, the removal efficiency of HCH ranged from 53.5 % to 96.9 % (83.9 % on average) depending on the flow rate. Removal efficiency was not uniform for individual HCH isomers but exhibited the trend: α = γ = δ > β = ε. The improved water quality was reflected in a biodiversity increase expressed by a number of phytobenthos (diatoms) species, a common biomarker of aquatic environment quality. The Wetland outranked the conventional WWTP in 10 out of the 15 general categories, and it is the most relevant scenario from the socio, environmental, and economic aspects.
- Klíčová slova
- Biodegradation, Bioindicators, Constructed wetland, Diatoms, Hexachlorocyclohexane, Lindane, Natural remediation, phytobenthos,
- MeSH
- biodegradace MeSH
- chemické látky znečišťující vodu * analýza MeSH
- čištění vody metody MeSH
- hexachlorcyklohexan * analýza MeSH
- mokřady * MeSH
- odpad tekutý - odstraňování metody MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chemické látky znečišťující vodu * MeSH
- hexachlorcyklohexan * MeSH
The hexachlorocyclohexane isomers (HCH) are long-banned pesticides. Even though their use has been prohibited for decades, their presence in the environment is still reported worldwide. Wetland + is a registered trademark of the remedial treatment technology consisting of an aerobic sedimentary tank, a permeable reactive barrier, a biosorption system, and an aerobic wetland. This proven method combines a reductive treatment known from PRBs with the natural wetland self-cleaning processes. The average efficiency of the system is 96.8% for chlorobenzenes (ClB) and 81.7% for HCH, during the first 12 months of the system operation. The presence of the genes encoding enzymes involved in the degradation of the HCH compounds indicates that the removal of HCH and ClB occurs not only by chemical removal but also through aerobic and anaerobic combining biodegradation. Changes in abundance and the composition of the diatom community were found to be suitable indicators of the water quality and of the impact of the Wetland + operation on the water ecosystem. The system's annual operation exhibited a markedly higher number of diatom species in the closing profiles of the Ostrovský Creek, the Wetland + effluent recipient.
- MeSH
- biodegradace MeSH
- biodiverzita MeSH
- ekosystém * MeSH
- hexachlorcyklohexan * chemie metabolismus MeSH
- mokřady MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- hexachlorcyklohexan * MeSH
A low-permeability locality with heterogeneous geology contaminated primarily by tetrachloroethene (PCE) present partially in the free phase in the unsaturated zone was treated on a pilot scale via direct push pneumatic fracturing combined with the hydraulic delivery of a remediation suspension consisting of milled iron, sulphidated nanosized zerovalent iron and sand in guar gum solution. Afterwards, a whey solution was injected into the fractures as a carbon source for bacteria. The unsaturated and saturated zones were treated. Long-term monitoring of the groundwater revealed that the abiotic reduction of PCE and trichloroethene was the dominant remediation processes for several months after the injections. A complex microbial consortium was developed that was capable of effective, long-term chlorinated ethenes (ClE) dechlorination. The consortium consisted mainly of Dehalococcoides but also of other anaerobic bacterial strains capable of partial dechlorination of ClE, including the sulphate-reducing bacteria; Geobacter and Desulfitobacterium. The average chlorine number in the groundwater decreased from 3.65 to 1.38 within 2.5 years after the injections, while the average ClE concentration increased from 13.5 to 31.5 mgL-1 because of the substantial acceleration of the ClE mass-transfer to the groundwater caused by the treatment. The remediation processes remained fully active for 2.5 years.
- Klíčová slova
- Chlorinated ethenes, Enhanced reductive dechlorination, Fracturing, Low permeability, Remediation, Zero valent iron,
- MeSH
- biodegradace MeSH
- chemické látky znečišťující vodu * analýza MeSH
- ethyleny MeSH
- podzemní voda * MeSH
- tetrachlorethylen * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chemické látky znečišťující vodu * MeSH
- ethylene MeSH Prohlížeč
- ethyleny MeSH
- tetrachlorethylen * MeSH
ISCO using activated sodium persulphate is a widely used technology for treating chlorinated solvent source zones. In sensitive areas, however, high groundwater sulphate concentrations following treatment may be a drawback. In situ biogeochemical transformation, a technology that degrades contaminants via reduced iron minerals formed by microbial activity, offers a potential solution for such sites, the bioreduction of sulphate and production of iron sulphides that abiotically degrade chlorinated ethenes acting as a secondary technology following ISCO. This study assesses this approach in the field using hydrochemical and molecular tools, solid phase analysis and geochemical modelling. Following a neutralisation and bioaugmentation, favourable conditions for iron- and sulphate-reducers were created, resulting in a remarkable increase in their relative abundance. The abundance of dechlorinating bacteria (Dehalococcoides mccartyi, Dehalobacter sp. and Desulfitobacterium spp.) remained low throughout this process. The activity of iron- and sulphate-reducers was further stimulated through application of magnetite plus starch and microiron plus starch, resulting in an increase in ferrous iron concentration (from
- Klíčová slova
- Biogeochemical transformation, Chlorinated solvents, Geochemical modelling, Indigenous microorganisms, Molecular tools, Solid phase analysis,
- MeSH
- chemické látky znečišťující vodu analýza metabolismus MeSH
- chlor metabolismus MeSH
- Chloroflexi metabolismus MeSH
- čištění vody metody MeSH
- Desulfitobacterium metabolismus MeSH
- ethyleny metabolismus MeSH
- halogenace MeSH
- oxidace-redukce MeSH
- Peptococcaceae metabolismus MeSH
- podzemní voda analýza chemie mikrobiologie MeSH
- regenerace a remediace životního prostředí metody MeSH
- rozpouštědla metabolismus MeSH
- sírany metabolismus MeSH
- sloučeniny sodíku MeSH
- tetrachlorethylen analýza metabolismus MeSH
- trichlorethylen analýza metabolismus MeSH
- železo metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
- Názvy látek
- chemické látky znečišťující vodu MeSH
- chlor MeSH
- ethylene MeSH Prohlížeč
- ethyleny MeSH
- rozpouštědla MeSH
- sírany MeSH
- sloučeniny sodíku MeSH
- sodium persulfate MeSH Prohlížeč
- tetrachlorethylen MeSH
- trichlorethylen MeSH
- železo MeSH
In situ bioremediation (ISB) using reductive dechlorination is a widely accepted but relatively slow approach compared to other technologies for the treatment of groundwater contaminated by chlorinated ethenes (CVOCs). Due to the known positive kinetic effect on microbial metabolism, thermal enhancement may be a viable means of accelerating ISB. We tested thermally enhanced ISB in aquifers situated in sandy saprolite and underlying fractured granite. The system comprised pumping, heating and subsequent injection of contaminated groundwater aiming at an aquifer temperature of 20-30°C. A fermentable substrate (whey) was injected in separate batches. The test was monitored using hydrochemical and molecular tools (qPCR and NGS). The addition of the substrate and increase in temperature resulted in a rapid increase in the abundance of reductive dechlorinators (e.g., Dehalococcoides mccartyi, Dehalobacter sp. and functional genes vcrA and bvcA) and a strong increase in CVOC degradation. On day 34, the CVOC concentrations decreased by 87% to 96% in groundwater from the wells most affected by the heating and substrate. On day 103, the CVOC concentrations were below the LOQ resulting in degradation half-lives of 5 to 6days. Neither an increase in biomarkers nor a distinct decrease in the CVOC concentrations was observed in a deep well affected by the heating but not by the substrate. NGS analysis detected Chloroflexi dechlorinating genera (Dehalogenimonas and GIF9 and MSBL5 clades) and other genera capable of anaerobic metabolic degradation of CVOCs. Of these, bacteria of the genera Acetobacterium, Desulfomonile, Geobacter, Sulfurospirillum, Methanosarcina and Methanobacterium were stimulated by the substrate and heating. In contrast, groundwater from the deep well (affected by heating only) hosted representatives of aerobic metabolic and aerobic cometabolic CVOC degraders. The test results document that heating of the treated aquifer significantly accelerated the treatment process but only in the case of an abundant substrate.
- Klíčová slova
- Biological reductive dechlorination, Chlorinated solvents, Indigenous microorganisms, NGS, Thermally enhanced bioremediation, qPCR,
- MeSH
- biodegradace * MeSH
- chemické látky znečišťující vodu izolace a purifikace MeSH
- Chloroflexi * MeSH
- podzemní voda chemie MeSH
- rozpouštědla izolace a purifikace MeSH
- sloučeniny chloru izolace a purifikace MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
- Názvy látek
- chemické látky znečišťující vodu MeSH
- rozpouštědla MeSH
- sloučeniny chloru MeSH
In this work, four series of tertiary amine-containing derivatives of 3,5-dinitrophenyl tetrazole and oxadiazole antitubercular agents were prepared, and their in vitro antimycobacterial effects were evaluated. We found that the studied compounds showed lipophilicity-dependent antimycobacterial activity. The N-benzylpiperazine derivatives, which had the highest lipophilicity among all of the series, showed the highest in vitro antimycobacterial activities against Mycobacterium tuberculosis CNCTC My 331/88 (H37Rv), comparable to those of the first-line drugs isoniazid and rifampicin. The presence of two tertiary amines in these N-benzylpiperazine derivatives enabled us to prepare water-soluble dihydrochloride salts, overcoming the serious drawback of previously described 3,5-dinitrophenyl tetrazole and oxadiazole lead compounds. The water-soluble 3,5-dinitrophenyl tetrazole and oxadiazole antitubercular agents described in this work are good candidates for further in vitro and in vivo pharmacokinetic and pharmacodynamic studies.
- Klíčová slova
- Antitubercular agent, Lipophilicity, Mycobacterium tuberculosis, Solubility, Structure-activity relationships, Tuberculosis,
- MeSH
- antituberkulotika chemická syntéza chemie farmakologie MeSH
- buněčné linie MeSH
- buňky Hep G2 MeSH
- Caco-2 buňky MeSH
- lidé MeSH
- mikrobiální testy citlivosti MeSH
- molekulární struktura MeSH
- Mycobacterium tuberculosis účinky léků MeSH
- oxadiazoly chemická syntéza chemie farmakologie MeSH
- proliferace buněk MeSH
- rozpustnost MeSH
- tetrazoly chemická syntéza chemie farmakologie MeSH
- viabilita buněk MeSH
- voda chemie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- antituberkulotika MeSH
- oxadiazoly MeSH
- tetrazoly MeSH
- voda MeSH
Biomolecular and hydrochemical tools were used to evaluate natural attenuation of chlorinated ethenes in a Quaternary alluvial aquifer located close to a historical source of large-scale tetrachloroethylene (PCE) contamination. Distinct stratification of redox zones was observed, despite the aquifer's small thickness (2.8 m). The uppermost zone of the target aquifer was characterised by oxygen- and nitrate-reducing conditions, with mixed iron- to sulphate-reducing conditions dominant in the lower zone, along with indications of methanogenesis. Natural attenuation of PCE was strongly influenced by redox heterogeneity, while higher levels of PCE degradation coincided with iron- to sulphate reducing conditions. Next generation sequencing of the middle and/or lower zones identified anaerobic bacteria (Firmicutes, Chloroflexi, Actinobacteria and Bacteroidetes) associated with reductive dechlorination. The relative abundance of dechlorinators (Dehalococcoides mccartyi, Dehalobacter sp.) identified by real-time PCR in soil from the lower levels supports the hypothesis that there is a significant potential for reductive dechlorination of PCE. Local conditions were insufficiently reducing for rapid complete dechlorination of PCE to harmless ethene. For reliable assessment of natural attenuation, or when designing monitoring or remedial systems, vertical stratification of key biological and hydrochemical markers should be analysed as standard, even in shallow aquifers.
- Klíčová slova
- Biological markers, Chlorinated solvents, Hydrochemical markers, Indigenous microorganisms, Natural attenuation,
- MeSH
- biodegradace MeSH
- chemické látky znečišťující vodu analýza MeSH
- Chloroflexi MeSH
- ethyleny analýza MeSH
- halogenace MeSH
- monitorování životního prostředí * MeSH
- podzemní voda chemie MeSH
- tetrachlorethylen chemie MeSH
- vysoce účinné nukleotidové sekvenování MeSH
- železo analýza MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chemické látky znečišťující vodu MeSH
- ethylene MeSH Prohlížeč
- ethyleny MeSH
- tetrachlorethylen MeSH
- železo MeSH
Contamination by chloroethenes has a severe negative effect on both the environment and human health. This has prompted intensive remediation activity in recent years, along with research into the efficacy of natural microbial communities for degrading toxic chloroethenes into less harmful compounds. Microbial degradation of chloroethenes can take place either through anaerobic organohalide respiration, where chloroethenes serve as electron acceptors; anaerobic and aerobic metabolic degradation, where chloroethenes are used as electron donors; or anaerobic and aerobic co-metabolic degradation, with chloroethene degradation occurring as a by-product during microbial metabolism of other growth substrates, without energy or carbon benefit. Recent research has focused on optimising these natural processes to serve as effective bioremediation technologies, with particular emphasis on (a) the diversity and role of bacterial groups involved in dechlorination microbial processes, and (b) detection of bacterial enzymes and genes connected with dehalogenation activity. In this review, we summarise the different mechanisms of chloroethene bacterial degradation suitable for bioremediation and provide a list of dechlorinating bacteria. We also provide an up-to-date summary of primers available for detecting functional genes in anaerobic and aerobic bacteria degrading chloroethenes metabolically or co-metabolically.
- Klíčová slova
- Biodegradation, Biological reductive dehalogenation, Cis-1,2-dichloroethene, Co-metabolic degradation, Organohalide respiration, Tetrachloroethene, Trichloroethene, Vinyl chloride,
- MeSH
- aerobní bakterie metabolismus MeSH
- Bacteria metabolismus MeSH
- biodegradace * MeSH
- halogenace MeSH
- tetrachlorethylen metabolismus MeSH
- vinylchlorid metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- tetrachlorethylen MeSH
- vinylchlorid MeSH
In this study, we described the structure-activity relationships of substituted 3,5-dinitrophenyl tetrazoles as potent antitubercular agents. These simple and readily accessible compounds possessed high in vitro antimycobacterial activities against Mycobacterium tuberculosis, including clinically isolated multidrug (MDR) and extensively drug-resistant (XDR) strains, with submicromolar minimum inhibitory concentrations (MICs). The most promising compounds showed low in vitro cytotoxicity and negligible antibacterial and antifungal activities, highlighting their highly selective antimycobacterial effects. 2-Substituted 5-(3,5-dinitrophenyl)-2H-tetrazole regioisomers, which are the dominant products of 5-(3,5-dinitrophenyl)-1H-tetrazole alkylation, showed better properties with respect to antimycobacterial activity and cytotoxicity than their 1-substituted counterparts. The 2-substituent of 5-(3,5-dinitrophenyl)-2H-tetrazole can be easily modified and can thus be used for the structure optimization of these promising antitubercular agents. The introduction of a tetrazole-5-thioalkyl moiety at position 2 of the tetrazole further increased the antimycobacterial activity. These compounds showed outstanding in vitro activity against M. tuberculosis (MIC values as low as 0.03 μM) and high activity against non-tuberculous mycobacterial strains.
- Klíčová slova
- Antitubercular agent, Mycobacterium tuberculosis, Regioisomers, Structure-activity relationships, Tetrazole, Tuberculosis,
- MeSH
- antituberkulotika chemie farmakologie MeSH
- druhová specificita MeSH
- lidé MeSH
- mikrobiální testy citlivosti MeSH
- mnohočetná léková rezistence účinky léků MeSH
- molekulární struktura MeSH
- Mycobacterium tuberculosis účinky léků MeSH
- tetrazoly chemie farmakologie MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antituberkulotika MeSH
- tetrazoly MeSH
Two new classes of antitubercular agents, namely 5-alkylsulfanyl-1-(3,5-dinitrophenyl)-1H-tetrazoles and 2-alkylsulfanyl-5-(3,5-dinitrophenyl)-1,3,4-oxadiazoles, and their structure-activity relationships are described. These compounds possessed excellent activity against Mycobacterium tuberculosis, including the clinically isolated multidrug (MDR) and extensively drug-resistant (XDR) strains, with no cross resistance with first or second-line anti-TB drugs. The minimum inhibitory concentration (MIC) values of the most promising compounds reached 0.03 μM. Furthermore, these compounds had a highly selective antimycobacterial effect because they were completely inactive against 4 gram positive and 4 gram negative bacteria and eight fungal strains and had low in vitro toxicity for four mammalian cell lines, including hepatic cell lines HepG2 and HuH7. Although the structure-activity relationship study showed that the presence of two nitro groups is highly beneficial for antimycobacterial activity, the analogues with a trifluoromethyl group instead of one of the nitro groups maintained a high antimycobacterial activity, which indicates the possibility for further structural optimization of this class of antitubercular agents.
- Klíčová slova
- Antitubercular agent, Mycobacterium tuberculosis, Oxadiazole, Structure-activity relationships, Tetrazole, Tuberculosis,
- MeSH
- antifungální látky chemická syntéza chemie farmakologie toxicita MeSH
- antituberkulotika chemická syntéza chemie farmakologie toxicita MeSH
- buňky Hep G2 MeSH
- léková rezistence účinky léků MeSH
- lidé MeSH
- mikrobiální testy citlivosti MeSH
- oxadiazoly chemie MeSH
- racionální návrh léčiv * MeSH
- sulfhydrylové sloučeniny chemická syntéza chemie farmakologie toxicita MeSH
- tetrazoly chemie MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- 1,3,4-oxadiazole MeSH Prohlížeč
- antifungální látky MeSH
- antituberkulotika MeSH
- oxadiazoly MeSH
- sulfhydrylové sloučeniny MeSH
- tetrazoly MeSH
