Wu W M, Hickey R F, Zeikus J G
Michigan Biotechnology Institute, Lansing 48909.
Appl Environ Microbiol. 1991 Dec;57(12):3438-49. doi: 10.1128/aem.57.12.3438-3449.1991.
Granules from an upflow anaerobic sludge blanket system treating a brewery wastewater that contained mainly ethanol, propionate, and acetate as carbon sources and sulfate (0.6 to 1.0 mM) were characterized for their physical and chemical properties, metabolic performance on various substrates, and microbial composition. Transmission electron microscopic examination showed that at least three types of microcolonies existed inside the granules. One type consisted of Methanothrix-like rods with low levels of Methanobacterium-like rods; two other types appeared to be associations between syntrophic-like acetogens and Methanobacterium-like organisms. The granules were observed to be have numerous vents or channels on the surface that extended into the interior portions of the granules that may be involved in release of gas formed within the granules. The maximum substrate conversion rates (millimoles per gram of volatile suspended solids per day) at 35 degrees C in the absence of sulfate were 45.1, 8.04, 4.14, and 5.75 for ethanol, acetate, propionate, and glucose, respectively. The maximum methane production rates (millimoles per gram of volatile suspended solids per day) from H2-CO2 and formate were essentially equal for intact granules (13.7 and 13.5) and for physically disrupted granules (42 and 37). During syntrophic ethanol conversion, both hydrogen and formate were formed by the granules. The concentrations of these two intermediates were maintained at a thermodynamic equilibrium, indicating that both are intermediate metabolites in degradation. Formate accumulated and was then consumed during methanogenesis from H2-CO2. Higher concentrations of formate accumulated in the absence of sulfate than in the presence of sulfate. The addition of sulfate (8 to 9 mM) increased the maximum substrate degradation rates for propionate and ethanol by 27 and 12%, respectively. In the presence of this level of sulfate, sulfate-reducing bacteria did not play a significant role in the metabolism of H2, formate, and acetate, but ethanol and propionate were converted via sulfate reduction by approximately 28 and 60%, respectively. In the presence of 2.0 mM molybdate, syntrophic propionate and ethanol conversion by the granules was inhibited by 97 and 29%, respectively. The data show that in this granular microbial consortium, methanogens and sulfate-reducing bacteria did not compete for common substrates. Syntrophic propionate and ethanol conversion was likely performed primarily by sulfate-reducing bacteria, while H2, formate, and acetate were consumed primarily by methanogens.
对一个上流式厌氧污泥床系统处理啤酒厂废水所产生的颗粒进行了表征，该啤酒厂废水主要含有乙醇、丙酸盐和乙酸盐作为碳源以及硫酸盐（0.6至1.0 mM），研究了其物理和化学性质、对各种底物的代谢性能以及微生物组成。透射电子显微镜检查表明，颗粒内部至少存在三种类型的微菌落。一种类型由类似甲烷丝菌的杆状体组成，同时含有少量类似甲烷杆菌的杆状体；另外两种类型似乎是类共生产乙酸菌与类似甲烷杆菌的生物体之间的联合体。观察到颗粒表面有许多通风口或通道，这些通道延伸到颗粒内部，可能与颗粒内形成的气体释放有关。在35℃且不存在硫酸盐的情况下，乙醇、乙酸盐、丙酸盐和葡萄糖的最大底物转化率（毫摩尔/克挥发性悬浮固体/天）分别为45.1、8.04、4.14和5.75。完整颗粒和物理破碎颗粒由H₂-CO₂和甲酸盐产生的最大甲烷生成率（毫摩尔/克挥发性悬浮固体/天）基本相等（分别为13.7和13.5以及42和37）。在乙醇的互营转化过程中，颗粒同时产生氢气和甲酸盐。这两种中间产物的浓度保持在热力学平衡状态，表明它们都是降解过程中的中间代谢产物。甲酸盐在由H₂-CO₂进行甲烷生成的过程中积累，然后被消耗。在不存在硫酸盐的情况下，甲酸盐积累的浓度高于存在硫酸盐时。添加硫酸盐（8至9 mM）分别使丙酸盐和乙醇的最大底物降解率提高了27%和12%。在这种硫酸盐水平下，硫酸盐还原菌在H₂、甲酸盐和乙酸盐的代谢中不起重要作用，但乙醇和丙酸盐分别通过硫酸盐还原作用转化了约28%和60%。在存在2.0 mM钼酸盐的情况下，颗粒对丙酸盐和乙醇的互营转化分别被抑制了97%和29%。数据表明，在这个颗粒状微生物群落中，产甲烷菌和硫酸盐还原菌不会竞争共同的底物。丙酸盐和乙醇的互营转化可能主要由硫酸盐还原菌进行，而H₂、甲酸盐和乙酸盐主要由产甲烷菌消耗。
