Kengen S W, Breidenbach C G, Felske A, Stams A J, Schraa G, de Vos W M
Laboratory of Microbiology, Department of Biomolecular Sciences, Wageningen University and Research Center, NL-6703 CT Wageningen, The Netherlands.
Appl Environ Microbiol. 1999 Jun;65(6):2312-6. doi: 10.1128/AEM.65.6.2312-2316.1999.
Thermophilic anaerobic biodegradation of tetrachloroethene (PCE) was investigated with various inocula from geothermal and nongeothermal areas. Only polluted harbor sediment resulted in a stable enrichment culture that converted PCE via trichloroethene to cis-1, 2-dichloroethene at the optimum temperature of 60 to 65 degrees C. After several transfers, methanogens were eliminated from the culture. Dechlorination was supported by lactate, pyruvate, fructose, fumarate, and malate as electron donor but not by H2, formate, or acetate. Fumarate and L-malate led to the highest dechlorination rate. In the absence of PCE, fumarate was fermented to acetate, H2, CO2, and succinate. With PCE, less H2 was formed, suggesting that PCE competed for the reducing equivalents leading to H2. PCE dechlorination, apparently, was not outcompeted by fumarate as electron acceptor. At the optimum dissolved PCE concentration of approximately 60 microM, a high dechlorination rate of 1.1 micromol h-1 mg-1 (dry weight) was found, which indicates that the dechlorination is not a cometabolic activity. Microscopic analysis of the fumarate-grown culture showed the dominance of a long thin rod. Molecular analysis, however, indicated the presence of two dominant species, both belonging to the low-G+C gram positives. The highest similarity was found with the genus Dehalobacter (90%), represented by the halorespiring organism Dehalobacter restrictus, and with the genus Desulfotomaculum (86%).
利用来自地热区和非地热区的各种接种物，对四氯乙烯（PCE）的嗜热厌氧生物降解进行了研究。只有受污染的港口沉积物产生了稳定的富集培养物，该培养物在60至65摄氏度的最佳温度下通过三氯乙烯将PCE转化为顺式-1,2-二氯乙烯。经过几次传代后，培养物中的产甲烷菌被消除。乳酸、丙酮酸、果糖、富马酸和苹果酸作为电子供体可支持脱氯作用，但氢气、甲酸或乙酸则不能。富马酸和L-苹果酸导致最高的脱氯速率。在没有PCE的情况下，富马酸发酵生成乙酸、氢气、二氧化碳和琥珀酸。有PCE存在时，生成的氢气较少，这表明PCE竞争导致氢气产生的还原当量。显然，PCE脱氯没有被富马酸作为电子受体的情况所超越。在大约60微摩尔的最佳溶解PCE浓度下，发现了1.1微摩尔·小时-1·毫克-1（干重）的高脱氯速率，这表明脱氯不是一种共代谢活性。对以富马酸生长的培养物进行显微镜分析显示，长细杆状菌占主导地位。然而，分子分析表明存在两种优势菌种，均属于低G+C革兰氏阳性菌。与脱卤杆菌属（90%）的相似性最高，以卤呼吸生物限制性脱卤杆菌为代表，与脱硫肠状菌属（86%）的相似性次之。
