Okabe Satoshi, Ito Tsukasa, Sugita Kenichi, Satoh Hisashi
Department of Urban and Environmental Engineering, Graduate School of Engineering, Hokkaido University, Kita-ku, Sapporo 060-8628, Japan.
Appl Environ Microbiol. 2005 May;71(5):2520-9. doi: 10.1128/AEM.71.5.2520-2529.2005.
The succession of sulfur-oxidizing bacterial (SOB) community structure and the complex internal sulfur cycle occurring in wastewater biofilms growing under microaerophilic conditions was analyzed by using a polyphasic approach that employed 16S rRNA gene-cloning analysis combined with fluorescence in situ hybridization, microelectrode measurements, and standard batch and reactor experiments. A complete sulfur cycle was established via S(0) accumulation within 80 days in the biofilms in replicate. This development was generally split into two phases, (i) a sulfur-accumulating phase and (ii) a sulfate-producing phase. In the first phase (until about 40 days), since the sulfide production rate (sulfate-reducing activity) exceeded the maximum sulfide-oxidizing capacity of SOB in the biofilms, H(2)S was only partially oxidized to S(0) by mainly Thiomicrospira denitirificans with NO(3)(-) as an electron acceptor, leading to significant accumulation of S(0) in the biofilms. In the second phase, the SOB populations developed further and diversified with time. In particular, S(0) accumulation promoted the growth of a novel strain, strain SO07, which predominantly carried out the oxidation of S(0) to SO(4)(2-) under oxic conditions, and Thiothrix sp. strain CT3. In situ hybridization analysis revealed that the dense populations of Thiothrix (ca. 10(9) cells cm(-3)) and strain SO07 (ca. 10(8) cells cm(-3)) were found at the sulfur-rich surface (100 microm), while the population of Thiomicrospira denitirificans was distributed throughout the biofilms with a density of ca. 10(7) to 10(8) cells cm(-3). Microelectrode measurements revealed that active sulfide-oxidizing zones overlapped the spatial distributions of different phylogenetic SOB groups in the biofilms. As a consequence, the sulfide-oxidizing capacities of the biofilms became high enough to completely oxidize all H(2)S produced by SRB to SO(4)(2-) in the second phase, indicating establishment of the complete sulfur cycle in the biofilms.
采用多相方法分析了在微需氧条件下生长的废水生物膜中硫氧化细菌（SOB）群落结构的演替以及发生的复杂内部硫循环，该方法采用16S rRNA基因克隆分析，并结合荧光原位杂交、微电极测量以及标准批次和反应器实验。在重复的生物膜中，通过80天内硫单质（S(0)）的积累建立了完整的硫循环。这一过程通常分为两个阶段：（i）硫积累阶段和（ii）硫酸盐生成阶段。在第一阶段（直到约40天），由于生物膜中硫化物产生速率（硫酸盐还原活性）超过了SOB的最大硫化物氧化能力，主要以反硝化硫微螺菌（Thiomicrospira denitirificans）利用硝酸根离子（NO(3)(-)）作为电子受体，硫化氢（H(2)S）仅部分被氧化为S(0)，导致生物膜中S(0)大量积累。在第二阶段，SOB种群随时间进一步发展并多样化。特别是，S(0)的积累促进了一种新菌株SO07的生长，该菌株在有氧条件下主要将S(0)氧化为硫酸根离子（SO(4)(2-)），还有丝状硫细菌（Thiothrix sp.）菌株CT3。原位杂交分析表明，在富含硫的表面（100微米）发现了密集的丝状硫细菌种群（约10(9)个细胞/立方厘米）和SO07菌株（约10(8)个细胞/立方厘米），而反硝化硫微螺菌种群分布在整个生物膜中，密度约为10(7)至10(8)个细胞/立方厘米。微电极测量表明，活性硫化物氧化区域与生物膜中不同系统发育的SOB群体的空间分布重叠。因此，生物膜的硫化物氧化能力变得足够高，能够在第二阶段将硫酸盐还原菌产生的所有H(2)S完全氧化为SO(4)(2-)，表明生物膜中建立了完整的硫循环。
