Bioremediation of di-(2-ethylhexyl) phthalate contaminated red soil by Gordonia terrae RL-JC02: Characterization, metabolic pathway and kinetics.

Di-(2-ethylhexyl) phthalate (DEHP) is the most widely used plasticizer and a representative endocrine disrupting chemical. The toxicological effects of DEHP on environmental and human health have been widely investigated. In this study, the DEHP-degrading bacterial strain RL-JC02 was isolated from red soil with long-term usage of plastic mulch, and it was identified as Gordonia terrae by 16S rRNA gene analysis coupled with physiological and biochemical characterization. The biodegrading capacity of different phthalic acid esters and related intermediates was investigated as well as the performance of strain RL-JC02 under different environmental conditions, such as temperature, pH, salinity and DEHP concentration. Specifically, strain RL-JC02 showed good tolerance to low pH, with 86.6% of DEHP degraded under the initial pH of 5.0 within 72 h. The metabolic pathway of DEHP was examined by metabolic intermediate identification via a high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) analysis in which DEHP was hydrolyzed into phthalic acid (PA) and 2-ethylhexanol (2-EH) via mono (2-ethylhexyl) phthalate (MEHP). PA and 2-EH were further utilized through the protocatechuic acid metabolic pathway and ß-oxidation via protocatechuic acid and 2-ethylhexanoic acid, respectively. The application potential of strain RL-JC02 was confirmed through the bioremediation of artificial DEHP-contaminated red soil showing 91.8% DEHP degradation by strain RL-JC02 within 30 d. The kinetics analysis of DEHP degradation by strain RL-JC02 in soil demonstrated that the process followed the modified Gompertz model. Meanwhile, the cell concentration monitoring of strain RL-JC02 in soil with absolute quantification polymerase chain reaction (qPCR) suggested that strain RL-JC02 survived well during bioremediation. This study provides sufficient evidence of a robust degrader for the bioremediation of PAE-contaminated red soil.

Complete genome sequence of a phthalic acid esters degrading Mycobacterium sp. YC-RL4

ABSTRACT Mycobacterium sp. YC-RL4 is capable of utilizing a broad range of phthalic acid esters (PAEs) as sole source of carbon and energy for growth. The preliminary studies demonstrated its high degrading efficiency and good performance during the bioprocess with environmental samples. Here, we present the complete genome of Mycobacterium sp. YC-RL4, which consists of one circular chromosome (5,801,417 bp) and one plasmid (252,568 bp). The genomic analysis and gene annotation were performed and many potential genes responsible for the biodegradation of PAEs were identified from the genome. These results may advance the investigation of bioremediation of PAEs-contaminated environments by strain YC-RL4.

Complete genome sequence of a phthalic acid esters degrading Mycobacterium sp. YC-RL4.

Mycobacterium sp. YC-RL4 is capable of utilizing a broad range of phthalic acid esters (PAEs) as sole source of carbon and energy for growth. The preliminary studies demonstrated its high degrading efficiency and good performance during the bioprocess with environmental samples. Here, we present the complete genome of Mycobacterium sp. YC-RL4, which consists of one circular chromosome (5,801,417bp) and one plasmid (252,568bp). The genomic analysis and gene annotation were performed and many potential genes responsible for the biodegradation of PAEs were identified from the genome. These results may advance the investigation of bioremediation of PAEs-contaminated environments by strain YC-RL4.

Biodegradation of phthalic acid esters by a newly isolated Mycobacterium sp. YC-RL4 and the bioprocess with environmental samples.

Bacterial strain YC-RL4, capable of utilizing phthalic acid esters (PAEs) as the sole carbon source for growth, was isolated from petroleum-contaminated soil. Strain YC-RL4 was identified as Mycobacterium sp. by 16S rRNA gene analysis and Biolog tests. Mycobacterium sp. YC-RL4 could rapidly degrade dibutyl phthalate (DBP), diethyl phthalate (DEP), dimethyl phthalate (DMP), dicyclohexyl phthalate (DCHP), and di-(2-ethylhexyl) phthalate (DEHP) under both individual and mixed conditions, and all the degradation rates were above 85.0 % within 5 days. The effects of environmental factors which might affect the degrading process were optimized as 30 °C and pH 8.0. The DEHP metabolites were detected by HPLC-MS and the degradation pathway was deduced tentatively. DEHP was transformed into phthalic acid (PA) via mono (2-ethylhexyl) phthalate (MEHP) and PA was further utilized for growth via benzoic acid (BA) degradation pathway. Cell surface hydrophobicity (CSH) assays illuminated that the strain YC-RL4 was of higher hydrophobicity while grown on DEHP and CSH increased with the higher DEHP concentration. The degradation rates of DEHP by strain YC-RL4 in different environmental samples was around 62.0 to 83.3 % and strain YC-RL4 survived well in the soil sample. These results suggested that the strain YC-RL4 could be used as a potential and efficient PAE degrader for the bioremediation of contaminated sites.

Biotransformations of bisphenols mediated by a novel Arthrobacter sp. strain YC-RL1.

Arthrobacter sp. strain YC-RL1, capable of utilizing bisphenol A (BPA) as sole carbon source for growth, was isolated from petroleum contaminated soil. YC-RL1 could rapidly degrade BPA in a wide range of pH (5.0-9.0) and temperature (20-40 °C). Substrate analysis found that YC-RL1 could also degrade bisphenol F (BPF) and tetrabromobisphenol A (TBBPA). The maximum and minimum concentrations of BPA (0.2-600 mg/L), BPF (0.2-600 mg/L), and TBBPA (0.2-300 mg/L) for efficient biodegradation were detected. The released bromide ion and metabolic intermediates of BPF and BPA/TBBPA were detected, as well as the degradation pathways for BPF and BPA/TBBPA were deduced tentatively. The present study provides important information for the investigation of BPs degrading mechanism and the application of microbial remediation in BP-contaminated environment. This study is the first report about a genus Arthrobacter bacterium which could simultaneously degrade BPA, BPF, and TBBPA.

Complete genome sequence of an aromatic compound degrader Arthrobacter sp. YC-RL1.

Arthrobacter sp. YC-RL1, isolated from a petroleum-contaminated soil, is capable of degrading and utilizing a wide range of aromatic compounds for growth. Here we report the complete genome sequence of strain YC-RL1, which may facilitate the investigation of environmental bioremediation and provide new gene resources for biotechnology and gene engineering.

[Biodegradation Characteristics and Kinetics of p-nitrophenol by Strain Arthrobacter sp. CN2].

To investigate the application potential of the p-nitrophenol-degrading bacterium Arthrobacter sp. CN2 in practice, the effects of pH, salinity and additional carbon source were determined, and the degradation kinetics of p-nitrophenol was analyzed. Strain CN2 could degrade p-nitrophenol efficiently in a wide range of pH (7.0-8.0) and elevated salinity (0-60 g · L(-1)). Investigation of additional glucose found that 0.5% of glucose could significantly increase the degrading speed and the time to reach 90% of degradation rate was shortened by 16 hours. These results indicated that strain CN2 could degrade p-nitrophenol efficiently under different conditions and had a great potential for application in practice.