Pojanakorn Charathirakup, Alissara Reungsang, and Wanpen Wirojanagud

pp. 109 - 116

Abstract

Methyl tertiary butyl ether (MTBE) is an oxygenated compound used to enhance the octane index
of gasoline and replace lead in gasoline. MTBE can reduce air pollution but causes water pollution due to its
high water solubility and low sorption to soil and thus can easily contaminate the environment. Biodegradation is one of the promising techniques to reduce MTBE contaminated in the environment and MTBE
degrader was proposed as an efficient method used to degrade MTBE. In this study, MTBE degraders were
isolated from gasoline contaminated soil and then were evaluated with the hypothesis that MTBE degraders
could improve biodegradation of MTBE in soil and mixed culture could degrade MTBE more rapidly than
monoculture. Gasoline contaminated soil samples were taken from retail gas stations and a motorcycle
repair shop in Khon Kaen University. Isolation of MTBE degrader was conducted by using Basal Salt
Medium (BSM) containing 200 mg/L of MTBE as a carbon source. Mixed culture of MTBE degrader was successfully isolated under aerobic condition. Morphology study was conducted by streaking isolated mixed
culture in solid medium, agar slant and identifying the cells shape under a microscope. It was found that this
mixed culture was a gram negative bacteria with 7 different isolates. A comparison of the ability to degrade
MTBE between mixed culture and monoculture was investigated in BSM containing 100 mg/L of MTBE.
The results indicated that a mixed culture degraded MTBE more rapidly than monoculture i.e. 20% within
14 days. Monoculture, J4 and J7, were the most rapid MTBE degraders among the other monocultures
in which they degraded 14% of MTBE in 14 days while monoculture J15 could degrade only 1% of MTBE.
This preliminary result suggests that mixed cultures degrade MTBE more efficiently than monoculture.