Goodwin KD, Schaefer JK, Oremland RS
United States Geological Survey, Menlo Park, California 94025, USA.
Appl Environ Microbiol. 1998 Dec;64(12):4629-36. doi: 10.1128/AEM.64.12.4629-4636.1998.
Bacterial oxidation of 14CH2Br2 and 14CH3Br was measured in freshwater, estuarine, seawater, and hypersaline-alkaline samples. In general, bacteria from the various sites oxidized similar amounts of 14CH2Br2 and comparatively less 14CH3Br. Bacterial oxidation of 14CH3Br was rapid in freshwater samples compared to bacterial oxidation of 14CH3Br in more saline waters. Freshwater was also the only site in which methyl fluoride-sensitive bacteria (e.g., methanotrophs or nitrifiers) governed brominated methane oxidation. Half-life calculations indicated that bacterial oxidation of CH2Br2 was potentially significant in all of the waters tested. In contrast, only in freshwater was bacterial oxidation of CH3Br as fast as chemical removal. The values calculated for more saline sites suggested that bacterial oxidation of CH3Br was relatively slow compared to chemical and physical loss mechanisms. However, enrichment cultures demonstrated that bacteria in seawater can rapidly oxidize brominated methanes. Two distinct cultures of nonmethanotrophic methylotrophs were recovered; one of these cultures was able to utilize CH2Br2 as a sole carbon source, and the other was able to utilize CH3Br as a sole carbon source.
在淡水、河口、海水和高盐碱性样品中测定了细菌对(^{14}CH_2Br_2)和(^{14}CH_3Br)的氧化作用。总体而言，来自不同地点的细菌氧化(^{14}CH_2Br_2)的量相似，而氧化(^{14}CH_3Br)的量相对较少。与在盐度较高的水中细菌对(^{14}CH_3Br)的氧化作用相比，淡水样品中细菌对(^{14}CH_3Br)的氧化作用较快。淡水也是唯一由对甲基氟敏感的细菌（如甲烷氧化菌或硝化细菌）主导溴化甲烷氧化的地点。半衰期计算表明，在所有测试的水体中，细菌对(CH_2Br_2)的氧化作用可能具有重要意义。相比之下，只有在淡水中细菌对(CH_3Br)的氧化作用与化学去除作用一样快。在盐度较高的地点计算得出的值表明，与化学和物理损失机制相比，细菌对(CH_3Br)的氧化作用相对较慢。然而，富集培养表明海水中的细菌能够快速氧化溴化甲烷。分离出了两种不同的非甲烷氧化甲基营养菌培养物；其中一种培养物能够将(CH_2Br_2)作为唯一碳源利用，另一种能够将(CH_3Br)作为唯一碳源利用。
