Biodegradation of Gasoline Oxygenate MTBE(Methyl tert-Butyl Ether) by Butane-Utilizing Bacteria

부탄분해미생물에 의한 가솔린첨가제 MTBE(Methyl tert-Butyl Ether) 분해

In this study, we have examined the potential degradation of MTBE(methyl tert-butyl ether) by pure culture ENV425 and mixed culture obtained from gasoline contaminated soil using n-butane as the sources of carbon and energy. The results described in this study suggest that MTBE is degraded cometabolically by ENV425 and mixed culture grown on n-butane. Butane and MTBE degradation was completely inhibited by acetylene, which indicated that both substrates were degraded by butane monooxygenase. These cultures grown on n-butane generated TBA (tert-butyl alcohol) as a metabolite of MTBE oxidation. TBA Production was accounted 54.7% and 58.6% for MTBE oxidation by ENV425 and mixed culture, respectively. In resting cell experiments, however, TBA and TBF were detected as the oxidation products of MTBE by ENV425 and mixed culture. The observed maximal MTBE degradation rates were 52.3 and 62.3 (nmol MTBE degraded/hr/mg TSS) by ENV425 and mixed culture, respectively, and the observed maximal transformation yields ($T_y$) were 44.7 and 34.0 (nmol MTBE degraded/$\mu$mol n-butane utilized), and the observed maximal transformation capacities ($T_c$) were 199 and 226 ($\mu$mol MTBE degraded/mg TSS used).

본 논문에서는 순수균주인 ENV425와 오염된 토양으로부터 분리한 혼합균주를 이용하여 가솔린 산화제인 MTBE에 대한 분해 가능성을 조사했다. MTBE는 n-butane에서 성장한 ENV425와 혼합균주에 의해 공대사적으로 분해가 이루어졌다. 또한 아세틸렌의 첨가에 의해 n-butane과 MTBE의 분해가 완전히 방해되어짐에 따라 두 기질 모두 부탄 분해 효소에 의해 분해되어짐을 알 수 있었다. n-butane에서 성장한 ENV42S와 혼합균주는 MTBE를 분해하고, MTBE의 분해산물로 TBA가 생성되었다. TBA의 생성은 분해된 MTBE에 대하여 ENV425와 혼합균주 각각 54.7%, 58.6%가 관찰되었다. 그러나, Resting cell 실험에서는 ENV425와 혼합균주에 의한 산화 생성물로 TBA와 TBF가 생성되었다. ENV425와 혼합균주에 의한 최대 MTBE 분해속도는 각각 52.3 그리고 62.3 (nmol MTBE degraded/hr/mg TSS), 최대 $T_y$ (Transformation yield)는 각각 44.7, 34.0 (nmol MTBE degraded/$\mu$mol n-butane utilized)으로 나타났고, 최대 $T_c$ (Transformation capacity)는 각각 199, 226 (nmol MTBE degraded/mg TSS used)으로 나타났다.