Lee Hanwoong, Choi Euiso, Yun Zuwhan, Park Yong Keun
Hazardous Substance Research Center-S&SW Louisiana State University, Baton Rouge, LA 70803, USA.
J Microbiol Biotechnol. 2008 Aug;18(8):1459-69.
Using a rotating biological contactor modified with a sequencing bath reactor system (SBRBC) designed and operated to remove phosphate and nitrogen, the microbial community structure of the biofilm from the SBRBC system was characterized based on the extracellular polymeric substance (EPS) constituents, electron microscopy, and molecular techniques. Protein and carbohydrate were identified as the major EPS constituents at three different biofilm thicknesses, where the amount of EPS and bacterial cell number were highest in the initial thickness of 0-100 microm. However, the percent of carbohydrate in the total amount of EPS decreased by about 11.23%, whereas the percent of protein increased by about 11.15% as the biofilm grew. Thus, an abundant quantity of EPS and cell mass, as well as a specific quality of EPS were apparently needed to attach to the substratum in the first step of the biofilm growth. A FISH analysis revealed that the dominant phylogenetic group was beta- and gamma-Proteobacteria, where a significant subclass of Proteobacteria for removing phosphate and/or nitrate was found within a biofilm thickness of 0-250 microm. In addition, 16S rDNA clone libraries revealed that Klebsiella sp. and Citrobacter sp. were most dominant within the initial biofilm thickness of 0-250 microm, whereas sulfur-oxidizing bacteria, such as Beggiatoa sp. and Thiothrix sp., were detected in a biofilm thickness over 250 microm. The results of the bacterial community structure analysis using molecular techniques agreed with the results of the morphological structure based on scanning electron microscopy. Therefore, the overall results indicated that coliform bacteria participated in the nitrate and phosphorus removal when using the SBRBC system. Moreover, the structure of the biofilm was also found to be related to the EPS constituents, as well as the nitrogen and phosphate removal efficiency. Consequently, since this is the first identification of the bacterial community and structure of the biofilm from an RBC simultaneously removing nitrogen and phosphate from domestic wastewater, and it is hoped that the present results may provide a foundation for understanding nitrate and phosphate removal by an RBC system.
使用一种经过改良的旋转生物接触器，该接触器与序批式反应器系统（SBRBC）相结合进行设计和运行，以去除磷酸盐和氮。基于胞外聚合物（EPS）成分、电子显微镜和分子技术，对SBRBC系统生物膜的微生物群落结构进行了表征。在三种不同生物膜厚度下，蛋白质和碳水化合物被确定为主要的EPS成分，其中在初始厚度0 - 100微米时，EPS量和细菌细胞数量最高。然而，随着生物膜生长，碳水化合物在EPS总量中的百分比下降了约11.23%，而蛋白质的百分比增加了约11.15%。因此，在生物膜生长的第一步，显然需要大量的EPS和细胞团以及特定质量的EPS来附着在基质上。荧光原位杂交（FISH）分析表明，主要的系统发育类群是β-和γ-变形菌，在0 - 250微米的生物膜厚度范围内发现了一个用于去除磷酸盐和/或硝酸盐的重要变形菌亚类。此外，16S rDNA克隆文库显示，克雷伯氏菌属（Klebsiella sp.）和柠檬酸杆菌属（Citrobacter sp.）在初始生物膜厚度0 - 250微米内最为占优势，而在生物膜厚度超过250微米时检测到了硫氧化细菌，如贝日阿托氏菌属（Beggiatoa sp.）和丝状硫细菌属（Thiothrix sp.）。使用分子技术进行细菌群落结构分析的结果与基于扫描电子显微镜的形态结构结果一致。因此，总体结果表明，使用SBRBC系统时大肠菌群参与了硝酸盐和磷的去除。此外，还发现生物膜的结构与EPS成分以及氮和磷的去除效率有关。因此，由于这是首次对同时从生活污水中去除氮和磷的旋转生物接触器生物膜的细菌群落和结构进行鉴定，希望目前的结果可为理解旋转生物接触器系统去除硝酸盐和磷酸盐提供基础。
