Stratification of activity and bacterial community structure in biofilms grown on membranes transferring oxygen
Stratification of activity and bacterial community structure in biofilms grown on membranes transferring oxygen
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DOI：
10.1128/aem.70.4.1982-1989.2004
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发表时间：
2004-04-01
影响因子：
4.4
通讯作者：
LaPara, TM
中科院分区：
文献类型：
--
作者：
Cole, AC;Semmens, MJ;LaPara, TM
已有研究表明，膜曝气生物膜反应器（MAB）可以在一个反应器中同时去除废水中的含碳和含氮污染物。氧气通过透气膜提供给MAB，使得最接近膜的区域富含氧气但有机碳含量低，而生物膜的外部区域没有氧气但富含有机碳。在这项研究中，MABs生长在类似的条件下，但在两个不同的流体速度（2和14厘米秒（-1））通过生物膜。MABs的生物量密度，呼吸活性和细菌群落结构的变化作为生物膜深度的函数进行了分析。生物量密度一般是最高的膜附近，并随着距离膜下降。呼吸活动表现出一个驼峰形的轮廓，最高的活动发生在中间的生物膜。通过PCR克隆和16 S rRNA基因的PCR-变性梯度凝胶电泳进行的群落分析表明，整个生物膜的群落结构具有实质性分层。还通过氨氧化细菌（AOB）（amoA）和反硝化细菌（nirK和nirS）特异性基因片段的竞争性定量PCR生成了种群分布。当流速为14 cm s（-1）时，AOB仅在膜附近出现，而反硝化细菌则在缺氧的生物膜外区增殖。相比之下，在流速为2 cm s（-1）时，AOB要么未检测到，要么检测到浓度接近检测限。本研究表明，在适当的条件下，AOB和反硝化细菌可以在MAB中共存。
Previous studies have shown that membrane-aerated biofilm (MAB) reactors can simultaneously remove carbonaceous and nitrogenous pollutants from wastewater in a single reactor. Oxygen is provided to MABs through gas-permeable membranes such that the region nearest the membrane is rich in oxygen but low in organic carbon, whereas the outer region of the biofilm is void of oxygen but rich in organic carbon. In this study, MABs were grown under similar conditions but at two different fluid velocities (2 and 14 cm s(-1)) across the biofilm. MABs were analyzed for changes in biomass density, respiratory activity, and bacterial community structure as functions of biofilm depth. Biomass density was generally highest near the membrane and declined with distance from the membrane. Respiratory activity exhibited a hump-shaped profile, with the highest activity occurring in the middle of the biofilm. Community analysis by PCR cloning and PCR-denaturing gradient gel electrophoresis of 16S rRNA genes demonstrated substantial stratification of the community structure across the biofilm. Population profiles were also generated by competitive quantitative PCR of gene fragments specific for ammonia-oxidizing bacteria (AOB) (amoA) and denitrifying bacteria (nirK and nirS). At a How velocity of 14 cm s(-1), AOB were found only near the membrane, whereas denitrifying bacteria proliferated in the anoxic outer regions of the biofilm. In contrast, at a flow velocity of 2 cm s(-1), AOB were either not detected or detected at a concentration near the detection limit. This study suggests that, under the appropriate conditions, both AOB and denitrifying bacteria can coexist within an MAB.