Pender Seán, Toomey Margaret, Carton Micheál, Eardly Dónal, Patching John W, Colleran Emer, O'Flaherty Vincent
Environmental Research Unit, Department of Microbiology, National University of Ireland, Galway, Ireland.
Water Res. 2004 Feb;38(3):619-30. doi: 10.1016/j.watres.2003.10.055.
The diversity, population dynamics, and activity profiles of methanogens in anaerobic granular sludges from two anaerobic hybrid reactors treating a molasses wastewater both mesophilically (37 degrees C) and thermophilically (55 degrees C) during a 1081 day trial were determined. The influent to one of the reactors was supplemented with sulphate, after an acclimation period of 112 days, to determine the effect of competition with sulphate-reducing bacteria on the methanogenic community structure. Sludge samples were removed from the reactors at intervals throughout the operational period and examined by amplified ribosomal DNA (rDNA) restriction analysis (ARDRA) and partial sequencing of 16S rRNA genes. In total, 18 operational taxonomic units (OTUs) were identified, 12 of which were sequenced. The methanogenic communities in both reactors changed during the operational period. The seed sludge and the reactor biomass sampled during mesophilic operation, both in the presence and absence of sulphate, was characterised by a predominance of Methanosaeta spp. Following temperature elevation, the dominant methanogenic sequences detected in the non-sulphate supplemented reactor were closely related to Methanocorpusculum parvum. By contrast, the dominant OTUs detected in the sulphate-supplemented reactor upon temperature increase were related to the hydrogen-utilising methanogen, Methanobacterium thermoautotrophicum. The observed methanogenic community structure in the reactors correlated with the operational performance of the reactors during the trial and with physiological measurements of the reactor biomass. Both reactors achieved chemical oxygen demand (COD) removal efficiencies of over 90% during mesophilic operation, with or without sulphate supplementation. During thermophilic operation, the presence of sulphate resulted in decreased reactor performance (effluent acetate concentrations of >3000 mg/l and biogas methane content of <25%). It was demonstrated that methanogenic conversion of acetate at 55 degrees C was extremely sensitive to inhibition by sulphide (50% inhibition at 8-17 mg/l unionised sulphide at pH 7.6-8.0), while the conversion of H(2)/CO(2) methanogenically was favoured. The combination of experiments carried out demonstrated the presence of specific methanogenic populations during periods of successful operational performance.
在一项为期1081天的试验中，测定了两个厌氧复合反应器中厌氧颗粒污泥中产甲烷菌的多样性、种群动态和活性特征。这两个反应器用于中温（37℃）和高温（55℃）处理糖蜜废水。在112天的适应期后，向其中一个反应器的进水补充硫酸盐，以确定与硫酸盐还原菌竞争对产甲烷菌群落结构的影响。在整个运行期间，定期从反应器中取出污泥样品，通过扩增核糖体DNA（rDNA）限制性分析（ARDRA）和16S rRNA基因的部分测序进行检测。总共鉴定出18个操作分类单元（OTU），其中12个进行了测序。在运行期间，两个反应器中的产甲烷菌群落均发生了变化。在中温运行期间，无论有无硫酸盐，接种污泥和反应器生物质的特征均为甲烷八叠球菌属占优势。温度升高后，在未补充硫酸盐的反应器中检测到的主要产甲烷序列与小甲烷颗粒菌密切相关。相比之下，在温度升高时，在补充了硫酸盐的反应器中检测到的主要OTU与利用氢气的产甲烷菌嗜热自养甲烷杆菌有关。在试验期间，观察到的反应器中产甲烷菌群落结构与反应器的运行性能以及反应器生物质的生理测量结果相关。在中温运行期间，无论是否补充硫酸盐，两个反应器的化学需氧量（COD）去除效率均超过90%。在高温运行期间，硫酸盐的存在导致反应器性能下降（出水乙酸盐浓度>3000mg/L，沼气甲烷含量<25%）。结果表明，55℃下乙酸盐的产甲烷转化对硫化物抑制极为敏感（在pH 7.6 - 8.0时，8 - 17mg/L非离子态硫化物下50%抑制），而氢气/二氧化碳的产甲烷转化则更受青睐。所进行的一系列实验表明，在运行成功期间存在特定的产甲烷菌群。
