Anaerobic Oxidation of Ethene Coupled to Sulfate Reduction in Microcosms and Enrichment Cultures

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• 作者：Heather Fullerton ; Michael Crawford ; Ademola Bakenne ; David L. Freedman ; Stephen H. Zinder
• 刊名：Environmental Science & Technology
• 出版年：2013
• 出版时间：November 5, 2013
• 年：2013
• 卷：47
• 期：21
• 页码：12374-12381
• 全文大小：390K
• 年卷期：v.47,no.21(November 5, 2013)
• ISSN：1520-5851

文摘

Ethene is considered recalcitrant under anaerobic conditions, but biological reduction to ethane and oxidation to CO₂ have been reported; however, little is known about these processes or the organisms carrying them out. In this report we describe sulfate dependent ethene consumption in microcosms prepared with sediments from a freshwater canal. A first dose of 0.6 mmol/L ethene was consumed within 77 days, and a second dose was largely consumed twelve days later. Material from this microcosm was transferred into growth medium with ethene as the only electron donor (except for trace amounts of vitamins) and sulfate as the electron acceptor. Four doses of ethene were consumed at increasing rates, and the cultures have been transferred at least eight times in this medium. Conversion of [¹⁴C]ethene primarily to ¹⁴CO₂ was demonstrated in fifth and sixth generation cultures, as well as production of sulfide in other cultures, confirming the ethene/sulfate couple. Ovoid cells 1鈥? 渭m in diameter were found in cultures containing ethene and sulfate, and quantitative PCR showed large increases in bacterial 16S rRNA gene copy number. Over half of a 16S rRNA gene clone library from a sixth-generation culture was a phylotype with a sequence ca. 90% identical with a clade of Deltaproteobacteria that includes Desulfovirga adipica and several Syntrophobacter spp. These studies have solidified the concept that deficits in mass balances for chloroethene fate in sulfate reducing zones of contaminated groundwater sites may be due to ethene oxidation, and suggest a unique phylotype is involved in this process.