Physiology and bioprocess of single cell of Stenotrophomonas maltophilia in bioremediation of co-existed benzo[a]pyrene and copper

Global responses to tris(1-chloro-2-propyl) phosphate and tris(2-butoxyethyl) phosphate in Escherichia coli: Evidences from biomarkers, and metabolic disturbance using GC-MS and LC-MS metabolomics analyses

Tris(1-chloro-2-propyl) phosphate (TCPP) and tris(2-butoxyethyl) phosphate (TBEP) as pollutants of emerging concern have aroused the rising attention due to their potential risks on aquatic ecosystem and public health. Nevertheless, there is a lack of toxicological mechanisms exploration of TCPP and TBEP at molecular levels. Herein, the toxicity effects and molecular mechanism of them were fully researched and summarized on Escherichia coli (E.coli). Acute exposure to them significantly activated antioxidant defense system and caused lipid peroxidation, as proved by the changes of antioxidant enzymes and MDA. The ROS overload resulted in the drop of membrane potential as well as the downregulated synthesis of ATPase, endorsing that E. coli cytotoxicity was ascribed to oxidative stress damage induced by TCPP and TBEP. The combination of GC-MS and LC-MS based metabolomics validated that TCPP and TBEP induced metabolic reprogramming in E.coli. More specifically, the responsive metabolites in carbohydrate metabolism, lipids metabolism, nucleotide metabolism, amino acid metabolism, and organic acids metabolism were significantly disturbed by TCPP and TBEP, confirming the negative effects on metabolic functions and key bioprocesses. Additionally, several biomarkers including PE(16:1(5Z)/15:0), PA(17:1(9Z)/18:2(9Z,12Z)), PE(19:1(9Z)/0:0), and LysoPE(0:0/18:1(11Z)) were remarkably upregulated, verifying that the protection of cellular membrane was conducted by regulating the expression of lipids-associated metabolites. Collectively, this work sheds new light on the potential molecular toxicity mechanism of TCPP and TBEP on aquatic organisms, and these findings using GC-MS and LC-MS metabolomics generate a fresh insight into assessing the effects of OPFRs on target and non-target aquatic organisms.

Application of flow cytometry for rapid, high-throughput, multiparametric analysis of environmental microbiomes

Quantification of the abundance and understanding of the dynamics of the microbial communities is essential to establish a basis for microbiome characterization. The conventional techniques used for the quantification of microbes are complicated and time-consuming. With scientific advancement, many techniques evolved and came into account. Among them, flow cytometry is a robust, high-throughput technique through which microbial dynamics, morphology, microbial distribution, physiological characteristics, and many more attributes can be studied in a high-throughput manner with comparatively less time and resources. Flow cytometry, when combined with other omics-based methods, offers a rapid and efficient platform to analyze and understand the composition of microbiome at the cellular level. The microbial diversity observed through flow cytometry will not be equivalent to that obtained by sequencing methods, but this integrated approach holds great potential for high throughput characterization of microbiomes. Flow cytometry is regarded as an established characterization tool in haematology, oncology, immunology, and medical microbiology research; however, its application in environmental microbiology is yet to be explored. This comprehensive review aims to delve into the diverse environmental applications of flow cytometry across various domains, including but not limited to bioremediation, landfills, anaerobic digestion, industrial bioprocesses, water quality regulation, and soil quality regulation. By conducting an in-depth analysis, this article seeks to shed light on the potential benefits and challenges associated with the utilization of flow cytometry in addressing environmental concerns.

Exploring the bioremediation capability of petroleum-contaminated soils for enhanced environmental sustainability and minimization of ecotoxicological concerns

The bioremediation of soils contaminated with petroleum hydrocarbons (PHCs) has emerged as a promising approach, with its effectiveness contingent upon various types of PHCs, i.e., crude oil, diesel, gasoline, and other petroleum products. Strategies like genetically modified microorganisms, nanotechnology, and bioaugmentation hold potential for enhancing remediation of polycyclic aromatic hydrocarbon (PAH) contamination. The effectiveness of bioremediation relies on factors such as metabolite toxicity, microbial competition, and environmental conditions. Aerobic degradation involves enzymatic oxidative reactions, while bacterial anaerobic degradation employs reductive reactions with alternative electron acceptors. Algae employ monooxygenase and dioxygenase enzymes, breaking down PAHs through biodegradation and bioaccumulation, yielding hydroxylated and dihydroxylated intermediates. Fungi contribute via mycoremediation, using co-metabolism and monooxygenase enzymes to produce CO2 and oxidized products. Ligninolytic fungi transform PAHs into water-soluble compounds, while non-ligninolytic fungi oxidize PAHs into arene oxides and phenols. Certain fungi produce biosurfactants enhancing degradation of less soluble, high molecular-weight PAHs. Successful bioremediation offers sustainable solutions to mitigate petroleum spills and environmental impacts. Monitoring and assessing strategy effectiveness are vital for optimizing biodegradation in petroleum-contaminated soils. This review presents insights and challenges in bioremediation, focusing on arable land safety and ecotoxicological concerns.

Differences in adsorption, transmembrane transport and degradation of pyrene and benzo[a]pyrene by Bacillus sp. strain M1

In a previous study our group identified Bacillus sp. strain M1 as an efficient decomposer of high molecular weight-polycyclic aromatic hydrocarbons (HMW-PAHs). Interestingly, its removal efficiency for benzo[a]pyrene (BaP) was nearly double that of pyrene (Pyr), which was the reverse of what is reported for most other species. Here we compared the differential steps of biosorption, transmembrane transport and biodegradation of Pyr and BaP by strain M1 in order to assist in targeted selection of dominant strains and their degradation efficiency in the remediation of these two HMW-PAHs. The overall biosorption efficiency for BaP was 19% higher than that for Pyr, and the time needed to reach BaP peak adsorption efficiency was 4 days shorter than for Pyr. Transmembrane transport of the PAHs was compared in presence of sodium azide which inhibits ATP synthesis and metabolism. This indicated that both Pyr and BaP entered the cells by the same means of passive transport. Biodegradation of Pyr and BaP did not differ in the early stage of culture, but around days 5-7, the biodegradation efficiency of BaP was significantly (30-61%) higher than that of Pyr. Key enzymes involved in these processes were identified and their activity differed, with intracellular gentisate 1,2-dioxygenase and extracellular polyphenol oxidase as likely candidates to be involved in BaP degradation, while intracellular catechol-1,2- dioxygenase and salicylate hydroxylase are more likely involved in Pyr degradation. These results provide new insights for sustainable environmental remediation of pyrene and benzo(a)pyrene by these bacteria.

Integration of transcriptomic and proteomic reveals the toxicological molecular mechanisms of decabromodiphenyl ethane (DBDPE) on Pleurotus ostreatus

Decabromodiphenyl ethane (DBDPE), as one of the most widely used new brominated flame retardants (NBFRs), can pose a potential threat to human health and the environment. An integrated transcriptome and proteome was performed for investigating the toxicological molecular mechanisms of Pleurotus ostreatus (P. ostreatus) during the biodegradation of DBDPE at the concentrations of 5 and 20 mg/L. A total of 1193/1018 and 92/126 differentially expressed genes/proteins (DEGs/DEPs) were found, respectively, with DBDPE exposure at 5 and 20 mg/L. These DEGs and DEPs were mainly involved in the cellular process as well as metabolic process. DEPs for oxidation-reduction process and hydrolase activity were up-regulated, and those for membrane, lipid metabolic process and transmembrane transport were down-regulated. The DEGs and DEPs related to some key enzymes were down-regulated, such as NADH dehydrogenase/oxidoreductase, succinate dehydrogenase, cytochrome C1 protein, cytochrome-c oxidase/reductase and ATP synthase, which indicated that DBDPE affected the oxidative phosphorylation as well as tricarboxylic acid (TCA) cycle. Cytochrome P450 enzymes (CYPs) might be involved in DBDPE degradation through hydroxylation and oxidation. Some stress proteins were induced to resist DBDPE toxicity, including major facilitator superfamily (MFS) transporter, superoxide dismutase (SOD), molecular chaperones, heat shock proteins (HSP20, HSP26, HSP42), 60S ribosomal protein and histone H4. The findings help revealing the toxicological molecular mechanisms of DBDPE on P. ostreatus, aiming to improve the removal of DBDPE.

Metabolomic analysis and oxidative stress response reveals the toxicity in Escherichia coli induced by organophosphate flame retardants tris(2-chloroethyl) phosphate and triphenyl phosphate

Organophosphate flame retardants (OPFRs) are emerging environmental pollutants that are increasingly being used in consumer commodities. The adverse effects on biota induced by tris(2-chloroethyl) phosphate (TCEP) and triphenyl phosphate (TPHP) have become a growing concern. Unfortunately, toxic mechanisms at the molecular level for OPFRs in organisms are still lacking. Herein, Escherichia coli (E.coli) was exposed to TCEP and TPHP for 24 and 48 h to reveal oxidative stress response and molecular toxicity mechanisms. The results indicated that promotion of ROS overload occurred at higher dosages groups. The levels of SOD and CAT were significantly elevated along with the increase of MDA attributed to lipid peroxidation. Additionally, apoptosis rates increased, accompanied by a decline in membrane potential and Na⁺/K⁺-ATPase and Ca²⁺/Mg²⁺-ATPase contents, signifying that E. coli cytotoxicity induced by TCEP and TPHP was mediated by oxidative stress. Based on metabolomic analysis, different metabolic pathways were disrupted, including glycolysis/gluconeogenesis, pentose phosphate metabolism, purine metabolism, glutathione metabolism, amino acid biosynthesis, butanoate metabolism, alanine and aspartate metabolism. Most differentially expressed metabolites were downregulated, indicating an inhibitory effect on metabolic functions and key metabolic pathways. These findings generated new insights into the potential environmental risks of OPFRs in aquatic organisms.

Insights into biodegradation mechanisms of triphenyl phosphate by a novel fungal isolate and its potential in bioremediation of contaminated river sediment

In this study, Aspergillus sydowii FJH-1 isolated from soil was verified to be a novel triphenyl phosphate (TPhP) degrader. Biodegradation efficiency of TPhP by Aspergillus sydowii FJH-1 exceeded 90% within 6 days under the optimal conditions (pH 4-9, 30 ℃, initial concentration less than 20 mg/L). Proteomics analysis uncovered the proteins perhaps involved in hydrolysis, hydroxylation, methylation and sulfonation of TPhP and the primary intracellular adaptive responses of Aspergillus sydowii FJH-1 to TPhP stress. The expression of carboxylic ester hydrolase along with several thioredoxin- and glutathione-dependent oxidoreductases were induced to withstand the toxicity of TPhP. The presence of TPhP also caused obvious upregulation of proteins concerned with glycolysis, pentose phosphate pathway and tricarboxylic acid cycle. Data from toxicological tests confirmed that the cytotoxicity and phytotoxicity of TPhP was effectively decreased after treatment with Aspergillus sydowii FJH-1. Additionally, bioaugmentation with Aspergillus sydowii FJH-1 was available for promoting TPhP removal in real water and water-sediment system. Collectively, the present study offered a deeper insight into the biodegradation mechanism and pathway of TPhP by a newly screened fungal strain Aspergillus sydowii FJH-1 and validated the feasibility of applying this novel degrader in the bioremediation of TPhP-polluted matrices.

Comparative Genomic Analysis of Stenotrophomonas maltophilia Strain W18 Reveals Its Adaptative Genomic Features for Degrading Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants that are ubiquitous in the environment. Numerous bacteria have evolved to have degrading genes or pathways to degrade PAHs. Stenotrophomonas maltophilia strain W18 was found to be able to degrade PAHs. Including 43 other complete genome sequences of S. maltophilia strains, we performed a comparative genomic analysis of 44 S. maltophilia strains by running OrthoFinder. A KEGG pathway enrichment analysis of environmental and clinical isolates of S. maltophilia revealed that environmental isolates tended to enhance gene functions such as "energy metabolism," "amino acid metabolism," "xenobiotic biodegradation and metabolism," and "folding, sorting, and degradation." The pangenome of the 44 S. maltophilia strains was open, while the core genome was estimated to reach a steady plateau. Based on gene annotations, we inferred that most of the degradation potential came from the core genome of S. maltophilia, while character genes and accessory genes also contributed to the degradation ability of S. maltophilia W18. The genes expression level of core genes, character genes and accessory genes were proved by RT-qPCR experiment, and accessory genes encoding alcohol dehydrogenase were upregulated most compared with genes with similar functions. We performed a credible comparative genomic analysis of S. maltophilia strains. S. maltophilia W18 was set as a model PAH-degrading bacterium of this species in this study, which would provide guidance for understanding and predicting the degradation mechanisms of other PAH-degrading S. maltophilia strains lacking complete genome data or waiting to be determined. IMPORTANCE This study provided the latest comparative genomic analysis on Stenotrophomonas maltophilia strains and focused on analyzing their genomic features that allow them to adapt to natural environments. In this study, we set S. maltophilia W18 as a typical PAH-degrading strain of this species. By discussing the genomic adaptative features of degrading PAH, we can predict genomic adaptative features of other S. maltophilia PAH-degrading strains since the core function of this species is stable. The gene functions of how S. maltophilia environmental isolates are enhanced for adaptation to various natural environments compared with clinical isolates have been revealed. Combined with a pangenome analysis and RT-qPCR results, we have proved that core genes, character genes, and accessory genes are all involved in PAH degradation. Accessory genes encoding alcohol dehydrogenase were upregulated most compared with core and character genes with similar functions, which suggests that PAH metabolization potential might be enhanced by horizontal gene transfer.

Bioremediation of triphenyl phosphate by Pycnoporus sanguineus: Metabolic pathway, proteomic mechanism and biotoxicity assessment

So far, no information about the biodegradability of TPhP by white rot fungi has previously been made available, herein, Pycnoporus sanguineus was used as the representative to investigate the potential of white rot fungi in TPhP bioremediation. The results suggested that the biodegradation efficiency of 5 mg/L TPhP by P. sanguineus was 62.84% when pH was adjusted to 6 and initial glucose concentration was 5 g/L. Seven biodegradation products were identified, indicating that TPhP was biotransformed through oxidative cleavage, hydroxylation and methylation. The proteomic analysis revealed that cytochrome P450s, aromatic compound dioxygenase, oxidizing species-generating enzymes, methyltransferases and MFS general substrate transporters might occupy important roles in TPhP biotransformation. Carboxylesterase and glutathione S-transferase were induced to resist TPhP stress. The biotreatment by P. sanguineus contributed to a remarkable decrease of TPhP biotoxicity. Bioaugmentation with P. sanguineus could efficiently promote TPhP biodegradation in the water-sediment system due to the cooperation between P. sanguineus and some putative indigenous degraders, including Sphingobium, Burkholderia, Mycobacterium and Methylobacterium. Overall, this study provided the first insights into the degradation pathway, mechanism and security risk assessment of TPhP biodegradation by P. sanguineus and verified the feasibility of utilizing this fungus for TPhP bioremediation applications.

Differential Expression and PAH Degradation: What Burkholderia vietnamiensis G4 Can Tell Us?

Petroleum is the major energy matrix in the world whose refining generates chemical byproducts that may damage the environment. Among such waste, polycyclic aromatic hydrocarbons (PAH) are considered persistent pollutants. Sixteen of these are considered priority for remediation, and among them is benzo(a)pyrene. Amid remediation techniques, bioremediation stands out. The genus Burkholderia is amongst the microorganisms known for being capable of degrading persistent compounds; its strains are used as models to study such ability. High-throughput sequencing allows researchers to reach a wider knowledge about biodegradation by bacteria. Using transcripts and mRNA analysis, the genomic regions involved in this aptitude can be detected. To unravel these processes, we used the model B. vietnamiensis strain G4 in two experimental groups: one was exposed to benzo(a)pyrene and the other one (control) was not. Six transcriptomes were generated from each group aiming to compare gene expression and infer which genes are involved in degradation pathways. One hundred fifty-six genes were differentially expressed in the benzo(a)pyrene exposed group, from which 33% are involved in catalytic activity. Among these, the most significant genomic regions were phenylacetic acid degradation protein paaN, involved in the degradation of organic compounds to obtain energy; oxidoreductase FAD-binding subunit, related to the regulation of electrons within groups of dioxygenase enzymes with potential to cleave benzene rings; and dehydrogenase, described as accountable for phenol degradation. These data provide the basis for understanding the bioremediation of benzo(a)pyrene and the possible applications of this strain in polluted environments.

Cellular changes of microbial consortium GY1 during decabromodiphenyl ether (BDE-209) biodegradation and identification of strains responsible for BDE-209 degradation in GY1

Microbial consortium remediation has been considered to be a promising technique for BDE-209 elimination in water, soil and sediment. Herein, we studied malondialdehyde (MDA), membrane potential (MP), and reactive active species (ROS) of a microbial consortium GY1 exposed to BDE-209. The results indicated that the microbial antioxidant defense system was vulnerable by BDE-209. Both early and late apoptosis of microbial consortium induced by BDE-209 were observed. The sequencing results revealed that Stenotrophomonas, Microbacterium and Sphingobacterium in GY1 played major roles in BDE-209 degradation. Moreover, a novel facultative anaerobic BDE-209 degrading strain named Microbacterium Y2 was identified from GY1, by which approximately 56.1% of 1 mg/L BDE-209 was degraded within 7 days, and intracellular enzymes of which contributed great to the result. Overall, the current study provided new insights to deeply understand the mechanisms of BDE-209 degradation by microbial consortium.

Proteomic mechanism of decabromodiphenyl ether (BDE-209) biodegradation by Microbacterium Y2 and its potential in remediation of BDE-209 contaminated water-sediment system

The investigation of BDE-209 degradation by Microbacterium Y2 under different condition was conducted. Cell membrane permeability, cell surface hydrophobicity (CSH), membrane potential (MP) and reactive oxygen species (ROS) production were altered under BDE-209 stress. Eleven debrominated congeners were identified, suggesting that BDE-209 biodegradation by Microbacterium Y2 was dominantly a successive debromination process. Proteome analysis showed that the overexpression of haloacid dehalogenases, glutathione S-transferases (GSTs) and ATP-binding cassette (ABC) transporters might occupy important roles in BDE-209 biotransformation. Meanwhile, heat shock proteins (HSPs), ribonuclease E, oligoribonuclease (Orn) and ribosomal protein were activated to counter the BDE-209 toxicity. The up-regulated pyruvate dehydrogenase E1 component beta subunit and dihydrolipoamide dehydrogenase suggested that the pyruvate metabolism pathway was activated. Bioaugmentation of BDE-209 polluted water-sediments system with Microbacterium Y2 could efficiently improve BDE-209 removal. The detection of total 16S rRNA genes in treatment system suggested that Microbacterium (25.6 %), Luteimonas (14.3 %), Methylovorus (12.6 %), Hyphomicrobium (9.2 %) were the dominant genera and PICRUSt results further revealed that the diminution of BDE-209 was owed to cooperation between the introduced bacteria and aboriginal ones.

Characterization of an efficient estrogen-degrading bacterium Stenotrophomonas maltophilia SJTH1 in saline-, alkaline-, heavy metal-contained environments or solid soil and identification of four 17β-estradiol-oxidizing dehydrogenases

The efficient bioremediation of estrogen contamination in complex environments is of great concern. Here the strain Stenotrophomonas maltophilia SJTH1 was found with great and stable estrogen-degradation efficiency even under stress environments. The strain could utilize 17β-estradiol (E2) as a carbon source and degrade 90% of 10 mg/L E2 in a week; estrone (E1) was the first degrading intermediate of E2. Notably, diverse pH conditions (3.0-11.0) and supplements of 4% salinity, 6.25 mg/L of heavy metal (Cd²⁺ or Cu²⁺), or 1 CMC of surfactant (Tween 80/ Triton X-100) had little effect on its cell growth and estrogen degradation. The addition of low concentrations of copper and Tween 80 even promoted its E2 degradation. Bioaugmentation of strain SJTH1 into solid clay soil achieved over 80% removal of E2 contamination (10 mg/kg) within two weeks. Further, the whole genome sequence of S. maltophilia SJTH1 was obtained, and a series of potential genes participating in stress-tolerance and estrogen-degradation were predicted. Four dehydrogenases similar to 17β-hydroxysteroid dehydrogenases (17β-HSDs) were found to be induced by E2, and the four heterogenous-expressed enzymes could oxidize E2 into E1 efficiently. This work could promote bioremediation appliance potential with microorganisms and biodegradation mechanism study of estrogens in complex real environments.

Degradation mechanism, intermediates and toxicology assessment of tris-(2-chloroisopropyl) phosphate using ultraviolet activated hydrogen peroxide

Organophosphate flame retardants (OPFRs), one kind of emerging flame retardants, have received prevalent attention owing to their ubiquity in aquatic matrices and their characteristics of being refractory to biodegradation. In current research, the degradation mechanism of tris-(2-chloroisopropyl) phosphate (TCPP), one of OPFRs, and its toxicological evaluation using UV-driven hydroxyl radical oxidation were investigated. A pseudo-first order reaction was fitted with an apparent rate constant (K_obs) of 0.1328 min^-1 on transformation of TCPP in the case of CH₂O₂ 0.1 mM, pH 6.6-7.1 and 4.7 mW cm^-2 UV irradiation. High resolution mass spectroscopy analyses identified nine degradation products (eg., C₆H₁₃Cl₂O₄P (m/z 251.0002), C₉H₁₇Cl₂O₅P (m/z 307.0266), C₉H₁₇Cl₂O₆P (m/z 323.0217), C₉H₁₈Cl₃O₅P (m/z 343.0033)) during transformation of TCPP. The removal efficiency dropped by inhibitory effect of natural organic matters and anions, implying that the complete mineralization of TCPP may be difficult in actual water treatment process. The toxicity assessment has shown an decrease in reactive oxygen species (ROS) and apoptosis, membrane potential (MP) elevation of Escherichia coli, and biological molecular function revision (eg., metabolism and DNA biosynthesis), indicating that toxicity of degradation products were conspicuously decreased in comparison with intact TCPP. To sum up, effective detoxification of TCPP can be realized by a UV driving radical-based oxidation, which will provide an alternative safe treatment method to control TCPP in water matrix.

Oxidation degradation of tris-(2-chloroisopropyl) phosphate by ultraviolet driven sulfate radical: Mechanisms and toxicology assessment of degradation intermediates using flow cytometry analyses

Organophosphate flame retardants (OPFRs) were frequently detected in biotic and abiotic matrix owing to their persistence and recalcitrant degradation. Some specific OPFRs, such as tris-(2-chloroisopropyl) phosphate (TCPP), pose a significant potential risk to human health due to their high water solubility. Therefore, an environmentally sound and high efficient technique is in urgent need of controlling TCPP. This research is focused on degrading TCPP using ultraviolet-persulfate (UV/PS) technique. The degradation reaction of TCPP followed a pseudo-first order kinetics with an apparent rate constant (k_obs) at 0.1653 min^-1. As the photocatalytic reaction proceeded, TCPP was transformed to twelve degradation intermediates via the selective electron-transfer reactions induced by activated sulfate radical. Anions existence and pH value significantly inhibited the degradation efficiency, implying that it was hard for TCPP to reach up to complete mineralization in actual water treatment process. Additionally, toxicological assessment of degradation intermediate mixture was conducted using Flow cytometry (FCM) analyses, and the result showed that the intracellular reactive oxygen species (ROS) and cell apoptotic rates significantly declined, and membrane potential (MP) increased in comparison with original TCPP. On the other hand, the negative impacts of these degradation products on DNA biosynthesis in Escherichia coli were weakened based on cell cycle analysis, all of which indicated that toxicity of these degradation intermediates was obviously reduced via UV/PS treatment. To summarize, an appropriate mineralization is effective for TCPP detoxification, suggesting the feasibility of TCPP control using UV/PS treatment in water matrix.

Metabolic and proteomic mechanism of benzo[a]pyrene degradation by Brevibacillus brevis

Benzo[a]pyrene (BaP) is a model compound of polycyclic aromatic hydrocarbons. The relationship between its toxicity and some target biomolecules has been investigated. To reveal the interactions of BaP biodegradation and metabolic network, BaP intermediates, proteome, carbon metabolism and ion transport were analyzed. The results show that 76% BaP was degraded by Brevibacillus brevis within 7 d through the cleavage of aromatic rings with the production of 1-naphthol and 2-naphthol. During this process, the expression of xylose isomerase was induced for xylose metabolism, whereas, α-cyclodextrin could no longer be metabolized. Lactic acid, acetic acid and oxalic acid at 0.1-1.2 mg dm^-3 were released stemming from their enhanced biosynthesis in the pathways of pyruvate metabolism and citrate cycle, while 5-7 mg dm^-3 of PO₄^3- were transported for energy metabolism. The relative abundance of 43 proteins was significantly increased for pyruvate metabolism, citrate cycle, amino acid metabolism, purine metabolism, ribosome metabolism and protein synthesis.

Identification of novel pathways for biotransformation of tetrabromobisphenol A by Phanerochaete chrysosporium, combined with mechanism analysis at proteome level

The investigation of tetrabromobisphenol A (TBBPA) removal by Phanerochaete chrysosporium (P. chrysosporium) was conducted. Under optimal conditions (pH 5, inoculum size of 5% (v/v), initial glucose concentration of 5 g/L, TBBPA concentration of 5 mg/L), >97% of initial TBBPA was removed after 3 days. The TBBPA metabolites, tetrabromobisphenol A glycoside, tribromobisphenol A glycoside and monohydroxylated tetrabromobisphenol A, were identified for the first time by fungi transformation as being produced by glycosylation and oxidative hydroxylation, respectively. Proteome analysis showed that P. chrysosporium significantly upregulated cytochrome P450 monooxygenase, glutathione S-transferases, UDP-glucosyltransferase, O‑methyltransferase and other oxidoreductases for TBBPA oxidative hydroxylation, reductive debromination, glycosylation, O‑methylation and oxidative cleavage for detoxification. Data from cytotoxicity tests with human hepatocellular liver carcinoma (HepG2) confirmed that TBBPA toxicity was effectively decreased by P. chrysosporium treatment. Bioaugmentation with P. chrysosporium significantly improved the removal efficiency of TBBPA in water microcosms to 63.1% within 12 h. This study suggests that P. chrysosporium might be suitable for the removal of TBBPA from contaminated water.

Benzo(a)pyrene degradation by cytochrome P450 hydroxylase and the functional metabolism network of Bacillus thuringiensis

The relationship between benzo(a)pyrene biodegradation and certain target biomolecules has been investigated. To regulate the degradation process, the associated metabolism network must be clarified. To this end, benzo(a)pyrene degradation, carbon substrate metabolism and exometabolomic mechanism of Bacillus thuringiensis were analyzed. Benzo(a)pyrene was degraded through hydroxylation catalyzed by cytochrome P450 hydroxylase. After the treatment of 0.5 mg L^-1 of benzo(a)pyrene by 0.2 g L^-1 of cells for 9 d, biosorption and degradation efficiencies were measured at approximately 90% and 80%, respectively. During this process, phospholipid synthesis, glycogen, asparagine, arginine, itaconate and xylose metabolism were significantly downregulated, while glycolysis, pentose phosphate pathway, citrate cycle, amino sugar and nucleotide sugar metabolism were significantly upregulated. These findings offer insight into the biotransformation regulation of polycyclic aromatic hydrocarbons.

iTRAQ-based proteomic profiling of Pycnoporus sanguineus in response to co-existed tetrabromobisphenol A (TBBPA) and hexavalent chromium

In current study, we investigated the changes of proteome profiles of Pycnoporus sanguineus after a single exposure of Cr(VI), TBBPA and a combined exposure of TBBPA and Cr(VI), with the goal of illuminating the cellular mechanisms involved in the interactions of co-existed TBBPA and Cr(VI) with the cells of P. sanguineus at the protein level. The results revealed that some ATP-binding cassette (ABC) transporters were obviously induced by these pollutants to accelerate the transportation, transformation and detoxification of TBBPA and Cr(VI). Cr(VI) could inhibit the bioremoval of its organic co-pollutants TBBPA through suppressing the expression of several key proteins related to the metabolism of TBBPA by P. sanguineus, including two cytochrome P450s, pentachlorophenol 4-monooxygenase and glutathione S-transferases. Furthermore, Cr(VI) possibly reduced the cell vitality and growth of P. sanguineus by enhancing the expression of imidazole glycerol phosphate synthase as well as by decreasing the abundances of proteins associated with the intracellular metabolic processes, such as the tricarboxylic acid cycle, purine metabolism and glutathione biosynthesis, thereby adversely affecting the biotransformation of TBBPA. Cr(VI) also inhibited the expression of peptidyl prolyl cis/trans isomerases, thus causing the damage of cell membrane integrity. In addition, some important proteins participated in the resistance to Cr(VI) toxicity were observed to up-regulate, including heat shock proteins, 26S proteasome, peroxiredoxins and three critical proteins implicated in S-adenosyl methionine synthesis, which contributed to reducing the hazard of Cr(VI) to P. sanguineus. The results of this study provide novel insights into the physiological responses and molecular mechanism of white rot fungi P. sanguineus to the stress of concomitant TBBPA and Cr(VI).