Sulfate-reducing bacterial community structure and their contribution to carbon mineralization in a wastewater biofilm growing under microaerophilic conditions
Sulfate-reducing bacterial community structure and their contribution to carbon mineralization in a wastewater biofilm growing under microaerophilic conditions
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微需氧条件下生长的废水生物膜中硫酸盐还原细菌群落结构及其对碳矿化的贡献
DOI：
10.1007/s00253-003-1395-3
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发表时间：
2003
影响因子：
5
通讯作者：
H. Satoh
中科院分区：
文献类型：
--
作者：
Satoshi Okabe;Tsukasa Ito;H. Satoh
采用分子技术、钼酸盐抑制批量实验和微电极测量相结合的方法，研究了在微氧条件下生长的废水生物膜中硫酸盐还原菌（SRB）的群落结构及其对碳矿化的贡献。利用生物膜样品构建了细菌种群的16S rDNA克隆文库。将102个克隆分为53个操作分类单元（OTUs），其中克隆分布为：Cytophaga-Flexibacter-Bacteroides (41%), Proteobacteria (41%)， low-G+C革兰氏阳性菌（18%）和其他门（3%）。以丙酸盐、乙酸盐和H2为电子给体，构建SRB富集培养物的3个细菌克隆文库，进一步研究不同碳源修饰对SRB群落结构的影响。这些文库显示SRB克隆具有系统发育多样性，隶属于变形菌门三角洲亚类的6个主要SRB属。荧光原位杂交（FISH）分析显示，在该生物膜中，Desulfobulbus和Desulfonema是最丰富的SRB物种，并且在生物膜表面检测到较高的丰度（分别为2-4×109细胞cm-3和5×107丝cm-3）。微电极测量表明，当生物膜在以醋酸盐为唯一碳源的合成培养基中培养时，高硫酸盐还原活性定位在氧/缺氧界面下方的狭窄区域。相比之下，当生物膜在初级沉淀池出水的上清液中培养时，在整个缺氧层中发现了广泛的硫酸盐还原区。这可能是因为有机碳源从散装水扩散到生物膜中，并且在生物膜中产生了未知数量的挥发性脂肪酸。分子技术和特定抑制剂（钼酸盐）的批量实验相结合的方法清楚地表明，Desulfobulbus是SRB种群中一个重要的数字成员，也是该生物膜中丙酸氧化为醋酸盐的主要贡献者。然而，乙酸被硝酸还原菌优先利用，而不被利用乙酸的SRB利用。
The community structure of sulfate-reducing bacteria (SRB) and the contribution of SRB to carbon mineralization in a wastewater biofilm growing under microaerophilic conditions were investigated by combining molecular techniques, molybdate inhibition batch experiments, and microelectrode measurements. A 16S rDNA clone library of bacteria populations was constructed from the biofilm sample. The 102 clones analyzed were grouped into 53 operational taxonomic units (OTUs), where the clone distribution was as follows: Cytophaga-Flexibacter-Bacteroides (41%), Proteobacteria (41%), low-G+C Gram-positive bacteria (18%), and other phyla (3%). Three additional bacterial clone libraries were also constructed from SRB enrichment cultures with propionate, acetate, and H2 as electron donors to further investigate the differences in SRB community structure due to amendments of different carbon sources. These libraries revealed that SRB clones were phylogenetically diverse and affiliated with six major SRB genera in the delta-subclass of the Proteobacteria. Fluorescent in situ hybridization (FISH) analysis revealed that Desulfobulbus and Desulfonema were the most abundant SRB species in this biofilm, and this higher abundance (ca. 2–4×109 cells cm–3 and 5×107 filaments cm–3, respectively) was detected in the surface of the biofilm. Microelectrode measurements showed that a high sulfate-reducing activity was localized in a narrow zone located just below the oxic/anoxic interface when the biofilm was cultured in a synthetic medium with acetate as the sole carbon source. In contrast, a broad sulfate-reducing zone was found in the entire anoxic strata when the biofilm was cultured in the supernatant of the primary settling tank effluent. This is probably because organic carbon sources diffused into the biofilm from the bulk water and an unknown amount of volatile fatty acids was produced in the biofilm. A combined approach of molecular techniques and batch experiments with a specific inhibitor (molybdate) clearly demonstrated that Desulfobulbus is a numerically important member of SRB populations and the main contributor to the oxidation of propionate to acetate in this biofilm. However, acetate was preferentially utilized by nitrate-reducing bacteria but not by acetate-utilizing SRB.