Biodegradation of methyl tert-butyl ether by Methylibium petroleiphilum PM1 in poor nutrition solution

Abstract

In this study, degradation of methyl tert-butyl ether (MTBE) by resting cells of Methylibium petroleiphilum PM1 was performed in poor nutrition solution, major component of which was MTBE. It was found that the biomass was hard to increase in poor nutrition, and the MTBE degradation activity was enhanced by 4.65-fold when 1 mM of Ba²⁺ was added into deionized water. It was also found that the MTBE degradation could be significantly improved by the dissolved oxygen level. All of 50 mg L⁻¹ MTBE could be degraded under aerobic condition, while only 5% was degraded under anaerobic condition by resting cells in poor nutrition solution after 12 h. In the above solution, the degradation of tert-butyl alcohol (TBA) was found to be faster than that of MTBE, which suggested that TBA degradation might not be the limiting step in MTBE metabolism. While in the poor nutrition solution with the mixture of MTBE and TBA, the addition of TBA did not affect MTBE degradation while MTBE inhibited TBA degradation weakly, which suggested that different and independent enzymes were responsible for degrading such compounds. The success of MTBE degradation by PM1 cells in real contaminated groundwater demonstrated its feasibility to biodegrade MTBE under poor environment, and it also indicated the great potential of MTBE bioremediation by entrapped cells in future application.

Keywords:

• Methyl tert-butyl ether
• biodegradation
• resting cells
• poor nutrition

Acknowledgments

This study was sponsored by National Natural Science Foundations of China and Zhejiang Provincial Natural Science Foundations (Grant No. 20476099 & y504272). The authors are grateful to Dr. Kate M. Scow, with University of California at Davis, USA, for kindly supplying strain of PM1.