Coates J D, Ellis D J, Blunt-Harris E L, Gaw C V, Roden E E, Lovley D R
Department of Microbiology, Southern Illinois University, Carbondale 62901, USA.
Appl Environ Microbiol. 1998 Apr;64(4):1504-9. doi: 10.1128/AEM.64.4.1504-1509.1998.
To evaluate which microorganisms might be responsible for microbial reduction of humic substances in sedimentary environments, humic-reducing bacteria were isolated from a variety of sediment types. These included lake sediments, pristine and contaminated wetland sediments, and marine sediments. In each of the sediment types, all of the humic reducers recovered with acetate as the electron donor and the humic substance analog, 2,6-anthraquinone disulfonate (AQDS), as the electron acceptor were members of the family Geobacteraceae. This was true whether the AQDS-reducing bacteria were enriched prior to isolation on solid media or were recovered from the highest positive dilutions of sediments in liquid media. All of the isolates tested not only conserved energy to support growth from acetate oxidation coupled to AQDS reduction but also could oxidize acetate with highly purified soil humic acids as the sole electron acceptor. All of the isolates tested were also able to grow with Fe(III) serving as the sole electron acceptor. This is consistent with previous studies that have suggested that the capacity for Fe(III) reduction is a common feature of all members of the Geobacteraceae. These studies demonstrate that the potential for microbial humic substance reduction can be found in a wide variety of sediment types and suggest that Geobacteraceae species might be important humic-reducing organisms in sediments.
为了评估哪些微生物可能导致沉积环境中腐殖质的微生物还原作用，从多种沉积物类型中分离出了腐殖质还原菌。这些沉积物类型包括湖泊沉积物、原始和受污染的湿地沉积物以及海洋沉积物。在每种沉积物类型中，所有以乙酸盐作为电子供体、以腐殖质类似物2,6 - 蒽醌二磺酸盐（AQDS）作为电子受体而分离得到的腐殖质还原菌均属于地杆菌科。无论在固体培养基上分离之前是否富集了AQDS还原菌，还是从液体培养基中沉积物的最高阳性稀释度中分离得到，情况都是如此。所有测试的分离株不仅能够通过与AQDS还原偶联的乙酸盐氧化来保存能量以支持生长，而且还能够以高度纯化的土壤腐殖酸作为唯一电子受体来氧化乙酸盐。所有测试的分离株也都能够以Fe(III)作为唯一电子受体生长。这与之前的研究一致，之前的研究表明Fe(III)还原能力是地杆菌科所有成员的共同特征。这些研究表明，在多种沉积物类型中都存在微生物还原腐殖质的潜力，并表明地杆菌科物种可能是沉积物中重要的腐殖质还原生物。
