A series of single-well push–pull tests (SWPPTs) were performed to investigate the efficacy of isobutane (2-methylpropane) as a primary substrate for in situ stimulation of microorganisms able to cometabolically transform common groundwater contaminants, such as chlorinated aliphatic hydrocarbons and 1,4-dioxane (1,4-D). In biostimulation tests, the disappearance of isobutane relative to a nonreactive bromide tracer indicated an isobutane-utilizing microbial community rapidly developed in the aquifer around the test well. SWPPTs were performed as natural drift tests with first-order rates of isobutane consumption ranging from 0.4 to 1.4 day⁻¹. Because groundwater contaminants were not present at the demonstration site, isobutene (2-methylpropene) was used as a nontoxic surrogate to demonstrate cometabolic activity in the subsurface after biostimulation. The transformation of isobutene to isobutene epoxide (2-methyl-1,2-epoxypropane) illustrates the epoxidation process previously shown for common groundwater contaminants after cometabolic transformation by alkane-utilizing bacteria. The rate and extent of isobutene consumption and the formation and transformation of isobutene epoxide were greater in the presence of isobutane, with no evidence of primary substrate inhibition. Modeled concentrations of isobutane-utilizing biomass in microcosms constructed with groundwater collected before and after each SWPPT offered additional evidence that the isobutane-utilizing microbial community was stimulated in the aquifer. Experiments in groundwater microcosms also demonstrated that the isobutane-utilizing bacteria stimulated in the subsurface could cometabolically transform a mixture of co-substrates including isobutene, 1,1-dichloroethene, cis-1,2-dichloroethene, and 1,4-D with the same co-substrate preferences as the bacterium Rhodococcus rhodochrous ATCC strain 21198 after growth on isobutane. This study demonstrated the effectiveness of isobutane as primary substrate for stimulating in situ cometabolic activity and the use of isobutene as surrogate to investigate in situ cometabolic reactions catalyzed by isobutane-stimulated bacteria.

进行了一系列单井推拉试验 (SWPPT) 以研究异丁烷 (2-甲基丙烷) 作为原位刺激微生物的主要底物的功效，这些微生物能够通过代谢方式转化常见的地下水污染物，例如氯化脂肪烃和1,4-二恶烷 (1,4-D)。在生物刺激测试中，异丁烷相对于非反应性溴化物示踪剂的消失表明在测试井周围的含水层中迅速发展了利用异丁烷的微生物群落。SWPPTs 作为自然漂移测试进行，异丁烷消耗的一级速率范围为 0.4 至 1.4 天^-1. 由于示范地点不存在地下水污染物，异丁烯（2-甲基丙烯）被用作无毒替代物，以证明生物刺激后在地下的代谢活性。异丁烯向异丁烯环氧化物（2-甲基-1,2-环氧丙烷）的转化说明了先前显示的常见地下水污染物在利用烷烃的细菌进行代谢转化后的环氧化过程。在异丁烷存在的情况下，异丁烯消耗的速率和程度以及异丁烯环氧化物的形成和转化更大，没有初级底物抑制的证​​据。在每个 SWPPT 之前和之后收集地下水构建的微观世界中利用异丁烷的生物质的模拟浓度提供了额外的证据，表明含水层中利用异丁烷的微生物群落受到了刺激。地下水微观世界的实验还表明，在地下刺激的利用异丁烷的细菌可以共代谢转化包括异丁烯、1,1-二氯乙烯、顺式-1,2-二氯乙烯和 1,4-D 在异丁烷上生长后具有与细菌Rhodococcus rhodochrous ATCC 菌株 21198相同的共底物偏好。这项研究证明了异丁烷作为刺激原位代谢活性的主要底物的有效性，以及使用异丁烯作为替代物来研究异丁烷刺激的细菌催化的原位代谢反应。