François Alan, Mathis Hugues, Godefroy Davy, Piveteau Pascal, Fayolle Françoise, Monot Frédéric
Institut Français du Pétrole, Département de Microbiologie, 92852 Rueil-Malmaison Cedex, France.
Appl Environ Microbiol. 2002 Jun;68(6):2754-62. doi: 10.1128/AEM.68.6.2754-2762.2002.
A strain that efficiently degraded methyl tert-butyl ether (MTBE) was obtained by initial selection on the recalcitrant compound tert-butyl alcohol (TBA). This strain, a gram-positive methylotrophic bacterium identified as Mycobacterium austroafricanum IFP 2012, was also able to degrade tert-amyl methyl ether and tert-amyl alcohol. Ethyl tert-butyl ether was weakly degraded. tert-Butyl formate and 2-hydroxy isobutyrate (HIBA), two intermediates in the MTBE catabolism pathway, were detected during growth on MTBE. A positive effect of Co2+ during growth of M. austroafricanum IFP 2012 on HIBA was demonstrated. The specific rate of MTBE degradation was 0.6 mmol/h/g (dry weight) of cells, and the biomass yield on MTBE was 0.44 g (dry weight) per g of MTBE. MTBE, TBA, and HIBA degradation activities were induced by MTBE and TBA, and TBA was a good inducer. Involvement of at least one monooxygenase during degradation of MTBE and TBA was shown by (i) the requirement for oxygen, (ii) the production of propylene epoxide from propylene by MTBE- or TBA- grown cells, and (iii) the inhibition of MTBE or TBA degradation and of propylene epoxide production by acetylene. No cytochrome P-450 was detected in MTBE- or TBA-grown cells. Similar protein profiles were obtained after sodium dodecyl sulfate-polyacrylamide gel electrophoresis of crude extracts from MTBE- and TBA-grown cells. Among the polypeptides induced by these substrates, two polypeptides (66 and 27 kDa) exhibited strong similarities with known oxidoreductases.
通过在难降解化合物叔丁醇（TBA）上进行初步筛选，获得了一种能高效降解甲基叔丁基醚（MTBE）的菌株。该菌株是一种革兰氏阳性甲基营养菌，被鉴定为非洲分枝杆菌IFP 2012，它也能够降解叔戊基甲基醚和叔戊醇。乙基叔丁基醚的降解能力较弱。在以MTBE为生长底物的过程中，检测到了MTBE分解代谢途径中的两种中间产物甲酸叔丁酯和2-羟基异丁酸（HIBA）。结果表明，Co2+对非洲分枝杆菌IFP 2012在HIBA上的生长有积极作用。MTBE的比降解速率为0.6 mmol/（h·g）（干重）细胞，MTBE的生物量产量为每克MTBE 0.44 g（干重）。MTBE、TBA和HIBA的降解活性由MTBE和TBA诱导，且TBA是一种良好的诱导剂。MTBE和TBA降解过程中至少涉及一种单加氧酶，这表现为：（i）对氧气的需求；（ii）MTBE或TBA生长的细胞能将丙烯转化为环氧丙烷；（iii）乙炔对MTBE或TBA降解以及环氧丙烷生成的抑制作用。在MTBE或TBA生长的细胞中未检测到细胞色素P-450。MTBE和TBA生长细胞的粗提物经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳后，得到了相似的蛋白质图谱。在这些底物诱导产生的多肽中，有两种多肽（66 kDa和27 kDa）与已知的氧化还原酶有很强的相似性。
