Powell Sabrina N, Singleton David R, Aitken Michael D
Department of Environmental Sciences and Engineering, School of Public Health, CB#7431, 166 Rosenau Hall, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7431, USA.
Environ Sci Technol. 2008 Jun 1;42(11):4099-105. doi: 10.1021/es703007n.
We investigated enrichment with salicylate as a method to stimulate the degradation of polycyclic aromatic hydrocarbons (PAHs) by a microbial communityfrom a bioreactortreating PAH-contaminated soil. DNA-based stable isotope probing (SIP) was used to compare the effect of alternate methods of salicylate addition (spike vs slow, continuous addition) on the diversity of the enriched microbial community. After identification of salicylate degraders by SIP, real-time quantitative PCR (qPCR) primers were developed to quantify the abundances of three groups containing salicylate-utilizing organisms in the bioreactor community before and after enrichment. The different methods of salicylate addition were found to select for different microbial communities. Two groups containing salicylate-degrading bacteria increased in abundance substantially after enrichment by continuous addition of salicylate but did not increase in abundance in response to the spike addition, whereas a third group increased in abundance in response to both methods of salicylate addition. The initial rate of naphthalene mineralization increased significantly after enrichment by spike addition of salicylate, but neither phenanthrene nor benzo[a] pyrene mineralization rates were enhanced. Continuous addition of salicylate did not enhance the mineralization rate for any of the PAHs. These results suggest that enrichment with salicylate can select for naphthalene-degrading bacteria, but does not select for organisms responsible for degrading PAHs of higher molecular weight. Differences in microbial selection observed in this study that resulted from different rates of carbon source addition also have implications for the design of SIP experiments with water-soluble carbon sources.
我们研究了利用水杨酸盐进行富集，以此作为一种刺激生物反应器中微生物群落降解多环芳烃（PAHs）的方法，该生物反应器用于处理受PAH污染的土壤。基于DNA的稳定同位素探测（SIP）被用于比较水杨酸盐不同添加方式（脉冲式添加与缓慢连续添加）对富集微生物群落多样性的影响。通过SIP鉴定出水杨酸盐降解菌后，开发了实时定量PCR（qPCR）引物，用于定量富集前后生物反应器群落中含有利用水杨酸盐微生物的三组菌群的丰度。结果发现，水杨酸盐的不同添加方式选择了不同的微生物群落。连续添加水杨酸盐进行富集后，两组含有水杨酸盐降解菌的菌群丰度大幅增加，但脉冲式添加水杨酸盐后其丰度并未增加，而第三组菌群对两种水杨酸盐添加方式的响应均表现为丰度增加。脉冲式添加水杨酸盐进行富集后，萘的初始矿化速率显著提高，但菲和苯并[a]芘的矿化速率均未提高。连续添加水杨酸盐并未提高任何一种PAHs的矿化速率。这些结果表明，用水杨酸盐进行富集可以选择出萘降解菌，但不能选择出负责降解高分子量PAHs的微生物。本研究中观察到的因碳源添加速率不同而导致的微生物选择差异，也对水溶性碳源的SIP实验设计具有启示意义。
