Bacterial degradation of ethyl tert-butyl ether and study of the molecular mechanisms underlying its biodegradation

Identifier:  TDX:1270

Handle: https://hdl.handle.net/20.500.11797/TDX1270

Authors:  Gunasekaran, Vijayalakshmi

Abstract:
Ethyl tert-butyl ether (ETBE) is a commonly used fuel oxygenate in Europe, to reduce air pollution in automobile fuels. Continued use of ETBE may render water bodies contaminated as they are fairly soluble in water and also they could be a potential carcinogen. The aim of this study is to identify and study the potential biodegraders of ETBE from microbial source and also to understand the molecular mechanisms behind the degradation. Two bacterial consortia namely A and B were enriched with ETBE from gasoline contaminated water samples. Consortium A consisted of Methylovorus sp., and Xanthomonas sp., was found to degrade ETBE and BTX simultaneously and cometabolically along with methanol, while bacterial consortium B was able to grow alone on ETBE and degrade them. Consortium B degrades ETBE almost completely and even in higher concentrations of ETBE which made them to be better biodegrader of ETBE. Methylophilus sp., Pseudomonas sp., and Xanthomonas sp. were identified as the participating bacteria in ETBE degradation in consortium B. The proteomic analysis done on bacterial consortium B revealed that proteins related to ETBE metabolism, amino acid, transport, chaperons and energy metabolism were found to be up-regulated. On the other hand cytochrome P450 gene which is believed to initiate ETBE degradation, was identified in ETBE and MTBE degrading strain Achromobacter xylosoxidans MCM2/2/1. The identified nucleotide sequence of CYP from A. xylosoxidans MCM2/2/1 was submitted to NCBI under the accession number JX454599. Moreover, the newly identified CYP gene was cloned and heterologoulsy expressed in E.coli in order to study its potential in converting ETBE and other common pollutants in future.