期刊
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
卷 162, 期 -, 页码 139-146出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ecoenv.2018.06.090
关键词
Bacterial genome; Chromium biotransformation; Chromate reductase; Chromate transporter; Transcription profiles; Chromate reducing activity
资金
- Key Scientific Research Project of Hunan Province, China [2016SK2004]
- National Natural Science Foundation for Young Scientists of China [51304250]
- National Natural Science Foundation of China [51774338]
- Major Science and Technology Projects in Gansu Province [1602FKDC007]
- Programs for Science and Technology Development of Strategic Emerging Industries of Hunan Province, China [2016GK4044]
Here, Pannonibacter phragmitetus BB was investigated at genomic, genetic and protein levels to explore molecular mechanisms of chromium biotransformation, respectively. The results of Miseq sequencing uncovered that a high-qualified bacterial genome draft was achieved with 5.07 Mb in length. Three novel genes involved in chromate reduce and transport, named nitR, chrA1 and chrA2, were identified by alignment, annotation and phylogenetic tree analyses, which encode a chromate reductase (NitR) and two chromate transporters (ChrA1 and ChrA2). Reverse transcription real-time polymerase chain reaction (RT-qPCR) analyses showed that the relative quantitative transcription of the three genes as the maximum reduction rate of Cr(VI) were significantly up-regulated with the increasing initial Cr(VI) concentrations. However, at the maximum cell growth points nitR was in a low transcription level, while the transcription of chrA1 and chrA2 were hold at a relatively high level and decreased with the increasing initial Cr(VI) concentrations. The ex-situ chromate reducing activity of NitR was revealed a V-max of 34.46 mu mol/min/mg enzyme and K-m of 14.55 mu mol/L, suggesting feasibility of the reaction with Cr(VI) as substrate. The multiple alignment demonstrates that NitR is potentially a nicotinamide adenine dinucleotide phosphate (NADPH) dependent flavin mononucleotide (FMN) reductase of Class I chromate reductases. Our results will prompt a large-scaled bioremediation on the contaminated soils and water by Pannonibacter phragmitetus BB, taking advantage of uncovering its molecular mechanisms of chromium bio-transformation.
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