Cometabolic Conditions Research Articles

Multi-omic profiling of a novel activated sludge strain Sphingobacterium sp. WM1 reveals the mechanism of tetracycline biodegradation and its merits of potential application.

As an emerging pollutant, the antibiotic tetracycline (TC) has been consistently detected in wastewater and activated sludge. Biodegradation represents a potentially crucial pathway to dissipate TC contamination. However, few efficient TC-degrading bacteria have been isolated and a comprehensive understanding of the molecular mechanisms underlying TC degradation is still lacking. In this study, a novel TC-degrading bacterium, designated as Sphingobacterium sp. WM1, was successfully isolated from activated sludge. Strain WM1 exhibited a remarkable performance in degrading 50mg/L TC within 1 day under co-metabolic conditions. Genomic analysis of the strain WM1 unveiled the presence of three functional tetX genes. Unraveling the complex molecular mechanisms, transcriptome analysis highlighted the role of upregulated transmembrane transport and accelerated electron transport in facilitating TC degradation. Proteomics confirmed the up-regulation of proteins involved in cellular biosynthesis/metabolism and ribosomal processes. Crucially, the tetX gene-encoding protein showed a significant upregulation, indicating its role in TC degradation. Heterologous expression of the tetX gene resulted in TC dissipation from an initial 51.9mg/L to 4.2mg/L within 24h. The degradation pathway encompassed TC hydroxylation, transforming into TP461 and subsequent metabolites, which effectively depleted TC's inhibitory activity. Notably, the tetX genes in strain WM1 showed limited potential for horizontal gene transfer. Collectively, strain WM1's potent TC degradation capacity signals a promise for enhancing TC clean-up strategies.

Long-Chain Alkylphenol Biodegradation Potential of Soil Ascomycota

A total of 11 ascomycete strains destructing technical nonylphenol (NP) and 4-tert-octylphenol (4-t-OP) were isolated from NP-contaminated soddy-podzolic loamy soil (Leningrad Region, Russia). The isolates proved capable of degrading NP and 4-t-OP at a high load (300 mg/L). The most efficient Fusarium solani strain 8F degraded alkylphenols (APs) both in cometabolic conditions and in the absence of additional carbon and energy sources. A decrease in APs was due to biodegradation or biotransformation by the strain and, to a minor extent, absorption by fungal cells. NP and 4-t-OP half-lives were, respectively, 3.5 and 6.4 h in cometabolic conditions and 9 and 19.7 h in the absence of additional carbon and energy sources. Amounts of the lipid peroxidation product malondialdehyde (MDA) and reduced glutathione (GSH) increased during NP and 4-t-OP biodegradation in cometabolic conditions by 1.7 and 2 times, respectively, as compared with a control. A high GSH level in F. solani 8F cells potentially implicated the metabolite in both AP biodegradation and strain resistance to oxidative stress. The study is the first to report on the NP and 4-t-OP degradation by the ascomycete F. solani in cometabolic conditions and in the absence of additional carbon and energy sources. The high AP degradation potential of soil ascomycetes was assumed to provide a basis for new environmentally safe bioremediation technologies for purification of soils and natural and waste waters contaminated with endocrine disruptors.

Effect of Various Carbon and Nitrogen Sources on Decolorization of Textile Dyes by Pseudomonas taiwanensis Strain TNZ3

The co-substrate is a crucial component in the bio-decolorization process that helps bacteria to grow and carry out their fundamental functions. Different types of textile dyes with diverse chemical structures are frequently employed in the textile industry, and the most of them are resistant to biodegradation because of their xenobiotic nature. Due to the low carbon content of textile dyes, particularly of azo dyes, co-metabolic conditions are required for decolorization process. Hence, the current study was aimed to determine which striking carbon and nitrogen sources are preferred for generating co-metabolic conditions to decolorize the following dyes: Disperse Yellow-3, Malachite Green, Basic Red-18, and Reactive Blue-4. Different carbon and nitrogen sources were used to isolate, screen, and evaluate different bacterial strains for dye degradation. A potential bacterial strain Pseudomonas taiwanensis strain TNZ3 was identified based on 16s rDNA sequence and selected for further study. It was found that the presence of yeast, peptone, NH4Cl, sucrose, glucose, fructose, maltose, galactose, lactose, and starch in dye contaminated media effectively enhanced azo dye degradation rate by Pseudomonas taiwanensis strain TNZ3. In the medium inoculated with Pseudomonas taiwanensis strain TNZ3, sucrose and yeast with peptone extracts induced the greatest decolorization among diverse carbon and nitrogen sources. In all dyes, the maximum decolorization occurs at 1.5% yeast extract supplementation. The results made it abundantly clear that various carbon and nitrogen sources used as co-substrates played effective role on dye decolorization process.

Long-Chain Alkylphenols Biodegradation Potential of the Soil <i>Ascomycota</i>

A total of 11 strains ascomycetes-destructors of technical nonylphenol (NP) and 4-tert-octylphenol (4-t-OP) were isolated from nonylphenol-contaminated soddy-podzolic loamy soil (Leningrad Region, Russia). Fungal isolates are able to degrade NP and 4-t-OP at a high load (300 mg/L). The most effective Fusarium solani 8F strain has the ability to degrade alkylphenols (AP) both under cometabolic conditions and without additional carbon and energy sources. The decrease in AP is due to the processes of biodegradation and/or biotransformation by the studied strain and, to a small extent, due to sorption by fungal cells. The NP and 4-t-OP half-life under cometabolic conditions is 3.5 and 6.4 hours, respectively, and without additional carbon and energy sources, 9 and 19.7 hours, respectively. The amount of the lipid peroxidation product, malondialdehyde, as well as the reduced glutathione content in the process of NP and 4-t-OP biodegradation under cometabolic conditions increases by 1.7 and 2 times, respectively, compared with the control. The high level of reduced glutathione in F. solani 8F cells may indicate the participation of this metabolite both in the processes of AP biodegradation and in providing strain resistance to oxidative stress. To our knowledge, this is the first report on the degradation of NP and 4-t-OP by ascomycetous fungus F. solani both under cometabolic conditions and without additional carbon and energy sources. The revealed high potential of soil ascomycetes to degrade alkylphenols can be the basis for new environmentally safe bioremediation technologies for the purification of endocrine-disruptors conta-minated soils, natural and waste waters.

Investigation of neomycin biodegradation conditions using ericoid mycorrhizal and white rot fungal species

BackgroundIn the search for methods to biodegrade recalcitrant compounds, the use of saprotrophic fungi and white rot fungi, in particular belonging to the phylum Basidiomycota, has gained interest. This group of fungi possesses a battery of unspecific extracellular enzymes that can be utilized in the biodegradation of preferably phenolic compounds. In this work, it was investigated under which conditions the white rot fungus Trametes versicolor and the ericoid mycorrhizal fungus Rhizoscyphus ericae (belonging to the phylum Ascomycota) could be used to biodegrade the antibiotic aminoglycoside neomycin at co-metabolic conditions in which external nutrients were supplied. Furthermore, it was also investigated whether a biodegradation could be accomplished using neomycin as the sole nutrient.ResultsThe results show that both species can biodegrade neomycin 70% under co-metabolic conditions during a one-week time course and that Rhizoscyphus ericae is able to use neomycin as sole nutrient and to approximatively biodegrade it 60% under chosen non co-metabolic conditions.At selected conditions, the biodegradation of neomycin using Rhizoscyphus ericae was monitored by oxidation products of D-ribose which is a hydrolysis product of neomycin.ConclusionThe results are of general interest in the search for fungal species that can biodegrade recalcitrant compounds without the need of external nutrients. The key future application area that will be investigated is purification of waste from recombinant protein production in which neomycin, nutrients and E. coli with neomycin resistance genes are present.

Immobilized Stenotrophomonas maltophilia KB2 in Naproxen Degradation.

Immobilization is a commonly used method in response to the need to increase the resistance of microorganisms to the toxic effects of xenobiotics. In this study, a plant sponge from Luffa cylindrica was used as a carrier for the immobilization of the Stenotrophomonas maltophilia KB2 strain since such a carrier meets the criteria for high-quality carriers, i.e., low price and biodegradability. The optimal immobilization conditions were established as a temperature of 30 °C, pH 7.2, incubation time of 72 h, and an optical density of the culture of 1.4. The strain immobilized in such conditions was used for the biodegradation of naproxen, and an average rate of degradation of 3.8 µg/hour was obtained under cometabolic conditions with glucose. The obtained results indicate that a microbiological preparation based on immobilized cells on a luffa sponge can be used in bioremediation processes where it is necessary to remove the introduced carrier.

Synergistic role of bacterial consortium to biodegrade toxic dyes containing wastewater and its simultaneous reuse as an added value

The current environmental research has fascinated the sustainable exploitation of mix bacterial consortium to biodegrade the environmentally-related toxic compounds, including hazardous synthetic dyes. Based on the existing literature evidence, textile and other industrial waste effluents pollute the natural water bodies. Textile effluent contains synthetic dyes which are liberated in the environment without proper treatment. The presence of toxic dyes added to the textile effluents undoubtedly affects the flora and fauna as that untreated water is used for irrigation by local farmers. Many conventional and biological methods are in action for the treatment of wastewater. Physical and chemical processes are expensive as compared to microbial treatments. The use of microbial consortia generates efficient results. Wastewater is a valuable resource, however, up to 80% of wastewater is released to different water matrices. This discernment needs to change for a better tomorrow. In this context, herein, we present a robust microbial-assisted treatment and simultaneously reuse of the treated wastewater as an added value to induce plant growth. Thus, the microbial approach for textile waste treatment release by-product after degradation should be non-toxic for the environment. In the present study, the toxicity of synthetic textile dye named Reactive Red 120, Reactive Orange 122, Reactive Yellow 160, and Reactive Blue 19 was investigated using a bioassay method with plant species namely Sorghum bicolor. Plate and Pot experiment was conducted with respect to untreated Azo dyes, degraded metabolites obtained from single bacteria, and consortium. Efficient Seed germination (89%), shoot length (12.4 cm), root length (15.6 cm) of the plants were observed for bacterial consortium degraded metabolites exposed seeds after comparing with the control. The degraded metabolite also increases protein (45.56 mg/g) and sugar (3.15 mg/g) contents. Bioremediation of various textile industrial effluents saves the ecosystem from the harmful effects of hazardous dyes. The biological decolorization of the textile azo dyes was investigated under co-metabolic conditions. The degraded metabolites can be used to enhance crop productivity and for commercial application. This mandates the current and future research to develop economically feasible and environmentally sustainable wastewater treatment practices.

Removal of diclofenac by a local bacterial consortium: UHPLC-ESI-MS/MS analysis of metabolites and ecotoxicity assessment.

Diclofenac (DCF) belongs to the class of nonsteroidal anti-inflammatory drugs, which is one of the most consumed by population and detected in raw sewage. Several studies have reported variable removal rates by biodegradation of diclofenac in wastewater treatment plants (WWTPs). This study deals with the evaluation of the biodegradation of DCF by a bacterial consortium (obtained from pure cultures of Enterobacter hormaechei D15 and Enterobacter cloacea D16), which were isolated from household compost and Algerian WWTP, respectively, as sole carbon source and by co-metabolism, using glucose as carbon source. A 98% removal rate of DCF was observed when it is used as the sole carbon source, whilst only 44% of DCF was removed in co-metabolic conditions. Two metabolites were identified using ultra-high-performance liquid chromatography coupled to electrospray injection tandem mass spectrometry analysis (UHPLC-ESI-MS/MS); one of them was identified as 4'-hydroxy-DCF, and the second metabolite was suspected to be a nitro derivative of DCF, according to comparison with the literature. Biodegradation of DCF by this bacterial consortium generates relatively safe final by-products.

Degradation of diclofenac by new bacterial strains and its influence on the physiological status of cells

Diclofenac (DCF) is one of the most commonly utilized non-steroidal anti-inflammatory drugs (NSAIDs), which is known to pose an ecotoxicological threat. In this study, from activated sludge and contaminated soil, we isolated four new bacterial strains able to degrade DCF under mono-substrate and co-metabolic conditions with glucose supplementation. We found that the effectiveness of DCF removal is strictly strain-specific and the addition of the primary substrate is not always beneficial. To assess the multidirectional influence of DCF on bacterial cells we evaluated the alterations of increasing concentrations of this drug on membrane structure. A significant increase was observed in the content of 17:0 cyclo fatty acid, which is responsible for reduced fluidity and profound changes in membrane rigidity. The cell injury and oxidative stress were assessed with biomarkers used as endpoints of toxicity, i.e. catalase (CAT), superoxide dismutase (SOD), lipids peroxidation (LPX), and both intra- and extracellular alkaline and acid phosphatase activity. Results indicated that DCF induced oxidative stress, frequently intensified by the addition of glucose. However, the response of the microbial cells to the presence of DCF should not be generalized, since the overall picture of the particular alterations greatly varied for each of the examined strains.

Diclofenac Degradation-Enzymes, Genetic Background and Cellular Alterations Triggered in Diclofenac-Metabolizing Strain Pseudomonas moorei KB4.

Diclofenac (DCF) constitutes one of the most significant ecopollutants detected in various environmental matrices. Biological clean-up technologies that rely on xenobiotics-degrading microorganisms are considered as a valuable alternative for chemical oxidation methods. Up to now, the knowledge about DCF multi-level influence on bacterial cells is fragmentary. In this study, we evaluate the degradation potential and impact of DCF on Pseudomonas moorei KB4 strain. In mono-substrate culture KB4 metabolized 0.5 mg L−1 of DCF, but supplementation with glucose (Glc) and sodium acetate (SA) increased degraded doses up to 1 mg L−1 within 12 days. For all established conditions, 4′-OH-DCF and DCF-lactam were identified. Gene expression analysis revealed the up-regulation of selected genes encoding biotransformation enzymes in the presence of DCF, in both mono-substrate and co-metabolic conditions. The multifactorial analysis of KB4 cell exposure to DCF showed a decrease in the zeta-potential with a simultaneous increase in the cell wall hydrophobicity. Magnified membrane permeability was coupled with the significant increase in the branched (19:0 anteiso) and cyclopropane (17:0 cyclo) fatty acid accompanied with reduced amounts of unsaturated ones. DCF injures the cells which is expressed by raised activities of acid and alkaline phosphatases as well as formation of lipids peroxidation products (LPX). The elevated activity of superoxide dismutase (SOD) and catalase (CAT) testified that DCF induced oxidative stress.

Characterization of microbial species in the biodegradation of explosives, military shooting range, Kaduna, Nigeria

Kachia military firing range since 1965 in situ characterization of microbes present in explosives contaminated soils was investigated. Bacteria gram stain morphological and biochemical characterization of the different microbial isolates. Bacterial DNA extracted from soil samples was achieved using the 16SrRNA is amplified using Polymerase Chain Reaction with the following microbes (Lysini bacillus, Escherichia coli, Enterobacter spp, Bacillus subtilis, Klebsiella pneumomia, Achromobacter spp and Arcobacter spp) was confirmed and results compared with the sequence obtained from the nucleotide database of National Centre for Biotechnology Information (NCBI). Fungal species isolates are: Rhizopus spp, Aspergillus niger, Penicillium spp, Trametes versicolourand Phanorochate chrysoporium may adapted to metabolise the explosives and heavy metals contaminant xenobiotic by biodegradation. Percentage isolates occurrence: 75% Enterobacterspp (highest) and 33% Escherichia coli (lowest); 67% Aspergillus niger (highest); and 17% for Penicillium sppand Trametes versicolor (lowest) respectively. Microbial biodegradation of explosives is considered to be most favourable under co-metabolic conditions. Site study explosives treatment by bioremediation will requires bioaugmentation of isolated microbes for xenobiotic biodegradation. Explosives impacts on biodiversity was illuminated and treatments protocol

Microbial degradation of two highly persistent fluorinated fungicides - epoxiconazole and fludioxonil

Biodegradation of two highly persistent fluorinated fungicides, epoxiconazole (EPO) and fludioxonil (FLU), by microbial consortia enriched from estuarine sediment and agricultural soil is reported. After an enrichment period of 6 months, four microbial consortia were able to completely remove and defluorinate the fungicides in co-metabolic conditions. Defluorination was biologically mediated and results suggest it is not a primary catabolic step, as fungicide removal was always faster than its defluorination. Three of the four enriched consortia had similar biodegradation performances in the absence of a co-substrate. Biodegradation kinetics revealed that microbial degradation followed a first-order kinetics, with cultures being capable of biodegrading concentrations up to 10 mg L−1 of EPO or FLU, in a maximum of 21 days. Estimated half-life values for these compounds were significantly lower than those reported in literature, highlighting the unique metabolic performance of the obtained consortia. Analysis of their microbial composition revealed that they integrate several bacterial species belonging to the Proteobacteria phylum, with the most common genera being Pseudomonas, Ochrobactrum and Comamonas. This is the first study providing clear evidence on the biodegradation of EPO and FLU, opening doors for the design of bioremediation technologies for the recovery of ecosystems polluted with such recalcitrant compounds.

Mycoremediation of Old and Intermediate Landfill Leachates with an Ascomycete Fungal Isolate, Lambertella sp.

In the present study, an Ascomycete fungal strain, Lambertella sp., isolated from environmental polluted matrices, was tested for the capacity to reduce the contamination and the toxicity of intermediate and old landfill leachates. Batch tests in flasks, under co-metabolic conditions, were performed with two different old leachates, with suspended and immobilized Lambertella sp. biomass, resulting in a soluble chemical oxygen demand depletion of 70% and 45%, after 13 and 30 days, respectively. An intermediate landfill leachate was treated in lab-scale reactors operating in continuous conditions for three months, inoculated with immobilized Lambertella sp. biomass, in absence of co-substrates. The Lambertella sp. depleted the corresponding total organic carbon by 90.2%. The exploitability of the Lambertella sp. strain was evaluated also in terms of reduction of phyto-, cyto-, and mutagenicity of the different Landfill Leachates at the end of the myco-based treatment, resulting in an efficient depletion of leachate clastogenicity.

Aerobic cometabolism of tetrabromobisphenol A by marine bacterial consortia.

The coastal environments worldwide are subjected to increasing TBBPA contamination, but current knowledge on aerobic biodegradability of this compound by marine microbes is lacking. The aerobic removal of TBBPA using marine consortia under eight different cometabolic conditions was investigated here. Results showed that the composition and diversity of the TBBPA-degrading consortia had diverged after 120-day incubation. Pseudoalteromonas, Alteromonas, Glaciecola, Thalassomonas, and Limnobacter were the dominant genera in enrichment cultures. Furthermore, a combination of beef extract- and peptone-enriched marine consortia exhibited higher TBBPA removal efficiency (approximately 60%) than the other substrate amendments. Additionally, Alteromonas macleodii strain GCW was isolated from a culture of TBBPA-degrading consortium. This strain exhibited about 90% of degradation efficiency toward TBBPA (10 mg L-1) after 10 days of incubation under aerobic cometabolic conditions. The intermediates in the degradation of TBBPA by A. macleodii strain GCW were analyzed and the degradation pathways were proposed, involving β-scission, debromination, and nitration routes.

Aerobic biodegradation of tramadol by pre-adapted activated sludge culture: Cometabolic transformations and bacterial community changes during enrichment

The biodegradation of biorecalcitrant opioid drug tramadol (TRAM) was studied in a model biodegradation experiment performed with an enriched activated sludge culture pre-adapted to high concentration of TRAM (20 mg/L). TRAM and its transformation products (TPs) were determined by applying ultrahigh-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS), the sludge culture was characterized using a 16S rRNA gene amplicon sequencing, whereas ecotoxicological evaluation was performed based on determination of toxicity to freshwater algae. Tramadol removal was much faster (t1/2 = 1.3 days) and more efficient in glucose-containing mineral medium (cometabolic conditions) than in a medium without glucose. The elimination of the parent compound resulted in the formation of five TPs, two of which (TP 249 and TP 235) were identified as N-desmethyltramadol (N-DM TRAM) and N,N-didesmethyltramadol (N,N-diDM TRAM). The remaining 3 TPs (TP 277a-c) were isomeric compounds with an elemental composition of protonated molecules C16H24NO3 and a putative structure which involved oxidative modification of the dimethylamino group. Pronounced changes in the taxonomic composition of the activated sludge were observed during the enrichment, especially regarding an enhanced percentage of 8 genera (Bacillus, Mycobacterium, Enterobacter, Methylobacillus, Pedobacter, Xanthobacter, Leadbetterella and Kaistia), which might be related to the observed transformations. The removal of TRAM resulted in proportional reduction of algal toxicity, implying a positive result of the accomplished transformation processes.

Simulation of in situ biodegradation of 1,4-dioxane under metabolic and cometabolic conditions

Bioaugmentation is an option for aerobic remediation of groundwater contaminated with 1,4-dioxane. One approach uses microbes that cometabolize 1,4-dioxane following growth on a primary substrate (e.g., propane), whereas another uses microbes (e.g., Pseudonocardia dioxivorans CB1190) capable of using 1,4-dioxane as a sole substrate. The relative merits of these approaches are difficult to distinguish based on field data alone, and theoretical analyses of these processes have yet to be published. The objective of this study was to compare these remediation options using a transport model that incorporates advection, dispersion and biodegradation reactions described by multi-substrate Monod kinetics and co-inhibition effects. The transport model was coupled to an approximate steady-state air sparging simulation used to estimate gas (propane and oxygen) distribution at the field scale. The model was calibrated with field data for 1,4-dioxane and propane concentrations from a previously reported pilot study. The two remediation approaches were evaluated under different conditions that vary the initial concentration of 1,4-dioxane and the loading rates of oxygen, propane, and biomass. The metrics used to evaluate the remediation success were the time to reach an average 1,4-dioxane concentration of 1 μg L−1 and the percent of 1,4-dioxane biodegraded after 10 years of simulation. Results indicate that the initial concentration of 1,4-dioxane strongly influences which remediation approach is more effective. When initial concentrations were <10 mg L−1, propane-driven cometabolism led to faster remediation; whereas metabolic biodegradation was faster when initial concentrations were 10 mg L−1 or higher. Below 0.25 mg L−1, the viability of metabolic biodegradation improved, although cometabolism by propanotrophs still required less time to reach 1 μg L−1. Biomass injection rates had a strong effect on the rate of metabolism but not cometabolism because continuous input of primary substrate supported growth of propanotrophs. The performance of both cultures was negatively affected by a decrease in oxygen injection rate. The endogenous decay coefficient and the dispersion rate for biomass had a significant impact on cometabolic and metabolic biodegradation of 1,4-dioxane. The maximum specific rate for cometabolism of 1,4-dioxane, the dispersion rate for 1,4-dioxane, and effective porosity also had significant effects on the time to achieve remediation with propanotrophs.

Naproxen ecotoxicity and biodegradation by Bacillus thuringiensis B1(2015b) strain

High level of naproxen consumption leads to the appearance of this drug in the environment but its possible effects on non-target organisms together with its biodegradation are not well studied.The aim of this work was to evaluate naproxen ecotoxicity by using the Microbial Assay for Risk Assessment. Moreover, Bacillus thuringiensis B1(2015b) was tested for both ecotoxicity and the ability of this strain to degrade naproxen in cometabolic conditions. The results indicate that the mean value of microbial toxic concentration estimated by MARA test amounts to 1.66 g/L whereas EC50 of naproxen for B1(2015b) strain was 4.69 g/L. At toxic concentration, Bacillus thuringiensis B1(2015b) showed 16:0 iso 3OH fatty acid presence and an increase in the ratio of total saturated to unsaturated fatty acids. High resistance of the examined strain to naproxen correlated with its ability to degrade this drug in cometabolic conditions.The results of bacterial reverse mutation assay (Ames test) revealed that naproxen at concentrations above 1 g/L showed genotoxic effect but the response was not dose-dependent.Maximal specific naproxen removal rate was observed at pH 6.5 and 30 °C, and in the presence of 0.5 g/L glucose as a growth substrate. Kinetic analysis allowed estimation of the half saturation constant (Ks) and the maximum specific naproxen removal rate (qmax) as 6.86 mg/L and 1.26 mg/L day, respectively. These results indicate that Bacillus thuringiensis B1(2015b) has a high ability to degrade naproxen and is a potential tool for bioremediation.

Bacterial Biodegradation of 4-Monohalogenated Diphenyl Ethers in One-Substrate and Co-Metabolic Systems

The use of diphenyl ether (DE) and its 4-monohalogenated derivatives (4-HDE) as flame retardants, solvents, and substrates in biocide production significantly increases the risk of ecosystem contamination. Their removal is important from the point of view of environmental protection. The aim of this study was to evaluate the degradation processes of DE and 4-HDE by enzymes of the environmental bacterial strains under one-substrate and co-metabolic conditions. The study is focused on the biodegradation of DE and 4-HDE, the enzymatic activity of microbial strains, and the cell surface properties after contact with compounds. The results show that the highest biodegradation (96%) was observed for 4-chlorodiphenyl ether in co-metabolic culture with P. fluorescens B01. Moreover, the activity of 1,2-dioxygenase during degradation of 4-monohalogenated diphenyl ethers was higher than that of 2,3-dioxygenase for each strain tested. The presence of a co-substrate provoked changes in dioxygenase activity, resulting in the increased activity of 1,2-dioxygenase. Moreover, the addition of phenol as a co-substrate allowed for increased biodegradation of the diphenyl ethers and noticeable modification of the cell surface hydrophobicity during the process. All observations within the study performed have led to a deeper understanding of the contaminants’ biodegradation processes catalyzed by environmental bacteria.

Biodegradation study of methadone by adapted activated sludge: Elimination kinetics, transformation products and ecotoxicological evaluation

The biotransformation study of difficult-to-degrade opioid analgesic methadone (MTHD) was performed by activated sludge culture adapted to high concentration of methadone (10 mg/L). The study included determination of elimination kinetics of the parent compound, taxonomic characterization of microbial culture, identification of biotransformation products (TPs) and assessment of ecotoxicological effects of biotransformation processes. The chemical analyses were performed by ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry, whereas the ecotoxicological assessment was made based on determinations of toxicity to freshwater algae. Changes of the adapted sludge culture during the experiment were followed using the 16S rRNA gene amplicon sequencing. Depending on the experimental conditions, the elimination efficiency of methadone (10 mg/L) varied from 9% to 93% with the corresponding half-lives from 11.4 days to 1.5 days. A significantly faster elimination (t1/2 from 1.5 days to 5.8 days) was achieved at cometabolic conditions, using glucose-containing media, as compared to the experiments with MTHD as a single organic carbon source (t1/2 = 11.4 days). Moreover, increased biotransformation rate following the additional supplementation of ammonia, revealed a possible importance of nitrogen availability for the transformation at cometabolic conditions. The elimination of parent compound was associated with the formation of 3 different TPs, two of which were identical to main human metabolites of MTHD, 2-Ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline (EMDP). EDDP represented over 90% of the total TP concentration at the end of experiment. The biodegradation of MTHD was associated with a pronounced drop in algal toxicity, confirming a rather positive ecotoxicological outcome of the achieved biotransformation processes.

Paracetamol – toxicity and microbial utilization. Pseudomonas moorei KB4 as a case study for exploring degradation pathway

Paracetamol, a widely used analgesic and antipyretic drug, is currently one of the most emerging pollutants worldwide. Besides its wide prevalence in the literature only several bacterial strains able to degrade this compound have been described. In this study, we isolated six new bacterial strains able to remove paracetamol. The isolated strains were identified as the members of Pseudomonas, Bacillus, Acinetobacter and Sphingomonas genera and characterized phenotypically and biochemically using standard methods. From the isolated strains, Pseudomonas moorei KB4 was able to utilize 50 mg L−1 of paracetamol. As the main degradation products, p-aminophenol and hydroquinone were identified. Based on the measurements of specific activity of acyl amidohydrolase, deaminase and hydroquinone 1,2-dioxygenase and the results of liquid chromatography analyses, we proposed a mechanism of paracetamol degradation by KB4 strain under co-metabolic conditions with glucose. Additionally, toxicity bioassays and the influence of various environmental factors, including pH, temperature, heavy metals at no-observed-effective-concentrations, and the presence of aromatic compounds on the efficiency and mechanism of paracetamol degradation by KB4 strain were determined. This comprehensive study about paracetamol biodegradation will be helpful in designing a treatment systems of wastewaters contaminated with paracetamol.