Hydroxylation at Multiple Positions Initiated the Biodegradation of Indeno[1,2,3-cd]Pyrene in Rhodococcus aetherivorans IcdP1

Cometabolic degradation of pyrene with phenanthrene as substrate: assisted by halophilic Pseudomonas stutzeri DJP1

At present, cometabolic degradation is an extensive method for the biological removal of high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) in the marine environment. However, due to the refractory to degradation and high toxicity, there are few studies on pyrene (PYR) cometabolic degradation with phenanthrene (PHE) as substrate. In this study, a Pseudomonas stutzeri DJP1 strain isolated from sediments was used in the cometabolic system of PHE and PYR. The biomass and the activity of key enzymes such as dehydrogenase and catechol 12 dioxygenase of strain were improved, but the enhancement of biotoxicity resulted in the inhibition of cometabolism simultaneously. Seven metabolites were identified respectively in PYR, PHE degradation cultures. It was speculated that the cometabolism of PHE and PYR had a common phthalic acid pathway, and the degradation pathway of PHE was included in the downstream pathway of PYR. The functional genes such as PhdF, NidD and CatA involved in DJP1 degradation were revealed by Genome analysis. This study provides a reference for the biodegradation of PYR and PHE in real marine environment.

Update on new trend and progress of the mechanism of polycyclic aromatic hydrocarbon biodegradation by Rhodococcus, based on the new understanding of relevant theories: a review

Rapid industrial and societal developments have led to substantial increases in the use and exploitation of petroleum, and petroleum hydrocarbon pollution has become a serious threat to human health and the environment. Polycyclic aromatic hydrocarbons (PAHs) are primary components of petroleum hydrocarbons. In recent years, microbial remediation of PAHs pollution has been regarded as the most promising and cost-effective treatment measure because of its low cost, robust efficacy, and lack of secondary pollution. Rhodococcus bacteria are regarded as one of main microorganisms that can effectively degrade PAHs because of their wide distribution, broad degradation spectrum, and network-like evolution of degradation gene clusters. In this review, we focus on the biological characteristics of Rhodococcus; current trends in PAHs degradation based on knowledge maps; and the cellular structural, biochemical, and enzymatic basis of degradation mechanisms, along with whole genome and transcriptional regulation. These research advances provide clues for the prospects of Rhodococcus-based applications in environmental protection.

Potential Utilization of Bacterial Consortium of Symbionts Marine Sponges in Removing Polyaromatic Hydrocarbons and Heavy Metals, Review

Toxic materials in waste generally contain several components of the global trending pollutant category, especially PAHs and heavy metals. Bioremediation technology for waste management that utilizes microorganisms (bacteria) has not been fully capable of breaking down these toxic materials into simple and environmentally friendly chemical products. This review paper examines the potential application of a consortium of marine sponge symbionts with high performance and efficiency in removing PAHs and heavy metal contaminants. The method was carried out through a review of several related research articles by the author and published by other researchers. The results of the study conclude that the development of global trending pollutant (GTP) bioremediation technology could be carried out to increase the efficiency of remediation. Several types of marine sponge symbiont bacteria, hydrocarbonoclastic (R-1), metalloclastic (R-2), and metallo-hydro-carbonoclastic (R-3), have the potential to be applied to improve waste removal performance. A consortium of crystalline bacterial preparations is required to mobilize into GTP-exposed sites rapidly. Bacterial symbionts of marine sponges can be traced mainly to sea sponges, whose body surface is covered with mucus.

Potential Toxicity Risk Assessment and Priority Control Strategy for PAHs Metabolism and Transformation Behaviors in the Environment

In this study, 16 PAHs were selected as the priority control pollutants to summarize their environmental metabolism and transformation processes, including photolysis, plant degradation, bacterial degradation, fungal degradation, microalgae degradation, and human metabolic transformation. Meanwhile, a total of 473 PAHs by-products generated during their transformation and degradation in different environmental media were considered. Then, a comprehensive system was established for evaluating the PAHs by-products' neurotoxicity, immunotoxicity, phytotoxicity, developmental toxicity, genotoxicity, carcinogenicity, and endocrine-disrupting effect through molecular docking, molecular dynamics simulation, 3D-QSAR model, TOPKAT method, and VEGA platform. Finally, the potential environmental risk (phytotoxicity) and human health risks (neurotoxicity, immunotoxicity, genotoxicity, carcinogenicity, developmental toxicity, and endocrine-disrupting toxicity) during PAHs metabolism and transformation were comprehensively evaluated. Among the 473 PAH's metabolized and transformed products, all PAHs by-products excluding ACY, CHR, and DahA had higher neurotoxicity, 152 PAHs by-products had higher immunotoxicity, and 222 PAHs by-products had higher phytotoxicity than their precursors during biological metabolism and environmental transformation. Based on the TOPKAT model, 152 PAH by-products possessed potential developmental toxicity, and 138 PAH by-products had higher genotoxicity than their precursors. VEGA predicted that 247 kinds of PAH derivatives had carcinogenic activity, and only the natural transformation products of ACY did not have carcinogenicity. In addition to ACY, 15 PAHs produced 123 endocrine-disrupting substances during metabolism and transformation. Finally, the potential environmental and human health risks of PAHs metabolism and transformation products were evaluated using metabolic and transformation pathway probability and degree of toxic risk as indicators. Accordingly, the priority control strategy for PAHs was constructed based on the risk entropy method by screening the priority control pathways. This paper assesses the potential human health and environmental risks of PAHs in different environmental media with the help of models and toxicological modules for the toxicity prediction of PAHs by-products, and thus designs a risk priority control evaluation system for PAHs.

Anthracene and Pyrene Biodegradation Performance of Marine Sponge Symbiont Bacteria Consortium

Every petroleum-processing plant produces sewage sludge containing several types of polycyclic aromatic hydrocarbons (PAHs). The degradation of PAHs via physical, biological, and chemical methods is not yet efficient. Among biological methods, the use of marine sponge symbiont bacteria is considered an alternative and promising approach in the degradation of and reduction in PAHs. This study aimed to explore the potential performance of a consortium of sponge symbiont bacteria in degrading anthracene and pyrene. Three bacterial species (Bacillus pumilus strain GLB197, Pseudomonas stutzeri strain SLG510A3-8, and Acinetobacter calcoaceticus strain SLCDA 976) were mixed to form the consortium. The interaction between the bacterial consortium suspension and PAH components was measured at 5 day intervals for 25 days. The biodegradation performance of bacteria on PAH samples was determined on the basis of five biodegradation parameters. The analysis results showed a decrease in the concentration of anthracene (21.89%) and pyrene (7.71%), equivalent to a ratio of 3:1, followed by a decrease in the abundance of anthracene (60.30%) and pyrene (27.52%), equivalent to a ratio of 2:1. The level of pyrene degradation was lower than that of the anthracene due to fact that pyrene is more toxic and has a more stable molecular structure, which hinders its metabolism by bacterial cells. The products from the biodegradation of the two PAHs are alcohols, aldehydes, carboxylic acids, and a small proportion of aromatic hydrocarbon components.