Abstract

Growing use of recalcitrant fuel oxygenates like methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and diisopropyl ether (DIPE) poses serious threat to aquatic environments and drinking water sources. Mycolicibacterium sp. strain CH28 was isolated earlier as a potential degrader of DIPE. Optimal culture conditions for strain CH28 were determined to be 32 °C and pH 5.00–6.00. Substrate utilization tests revealed that several n-alkanes, aromatic compounds, short-chain alcohols and acids were metabolized by strain CH28. In resting cell assays, strain CH28 was able to mineralize DIPE with a degradation rate of 1.63 ± 0.03 nmol min⁻¹mg biomass⁻¹. Complete mineralization of 75 mg l⁻¹ DIPE occurred within 42 hours in microcosm systems using groundwater samples inoculated with strain CH28. 2-propanol, acetone, and acetate were identified as intermediates of DIPE degradation with GC-MS, and a degradation pathway was proposed. Mixed cultures of strain CH28 and Hydrogenophaga sp. strain T4 were able to fully mineralize 200 mg l⁻¹ ETBE in 60 hours. Moreover, strain CH28 could co-oxidize MTBE and TAME in the presence of DIPE as the growth substrate. Our results indicate that strain CH28 holds great potential in the bioremediation of sites contaminated with gasoline ether oxygenates.

摘要

甲基叔丁基醚 (MTBE)、乙基叔丁基醚 (ETBE)、叔戊基甲基醚 (TAME) 和二异丙基醚 (DIPE)等顽固性燃料含氧化合物的日益使用对水生环境和饮用水源构成严重威胁. 分枝杆菌属 菌株 CH28 较早被分离为 DIPE 的潜在降解剂。菌株 CH28 的最佳培养条件确定为 32 °C 和 pH 5.00–6.00。底物利用试验表明，菌株 CH28 代谢了几种正构烷烃、芳香族化合物、短链醇和酸。在静息细胞测定中，菌株 CH28 能够以 1.63 ± 0.03 nmol min ^-1 mg 生物量的降解速率矿化 DIPE^-1。使用接种了菌株 CH28 的地下水样品在 42 小时内发生了 75 mg l ^{-1 DIPE 的完全矿化。}2-丙醇、丙酮和醋酸盐被GC-MS鉴定为DIPE降解的中间体，并提出了降解途径。CH28 菌株和Hydrogenophaga sp的混合培养物。菌株 T4 能够在 60 小时内完全矿化 200 mg l ^{-1 ETBE。}此外，在 DIPE 作为生长底物存在的情况下，菌株 CH28 可以共氧化 MTBE 和 TAME。我们的研究结果表明，菌株 CH28 在被汽油醚含氧化合物污染的场地的生物修复中具有巨大的潜力。