Egli K, Bosshard F, Werlen C, Lais P, Siegrist H, Zehnder A J B, Van der Meer J R
Swiss Federal Institute for Environmental Science and Technology, CH-8600 Dübendorf, Switzerland.
Microb Ecol. 2003 May;45(4):419-32. doi: 10.1007/s00248-002-2037-5. Epub 2003 Apr 22.
High nitrogen losses were observed in a rotating biological contactor (RBC) treating ammonium-rich (up to 500 mg NH4(+)-N/L) but organic-carbon-poor leachate from a hazardous waste landfill in Kölliken, Switzerland. The composition and spatial structure of the microbial community in the biofilm on the RBC was analyzed with specific attention for the presence of aerobic ammonium and nitrite oxidizing bacteria and anaerobic ammonium oxidizers. Anaerobic ammonium oxidation (anammox) involves the oxidation of ammonium with nitrite to N2. First the diversity of the biofilm community was determined from sequencing cloned PCR-amplified 16S rDNA fragments. This revealed the presence of a number of very unusual 16S rDNA sequences, but very few sequences related to known ammonium or nitrite oxidizing bacteria. From analysis of biofilm samples by fluorescence in situ hybridization with known phylogenetic probes and by dot-blot hybridization of the same probes to total RNA purified from biofilm samples, the main groups of microorganisms constituting the biofilm were found to be ammonium-oxidizing bacteria from the Nitrosomonas europaea/eutropha group, anaerobic ammonium-oxidizing bacteria of the "Candidatus Kuenenia stuttgartiensis" type, filamentous bacteria from the phylum Bacteroidetes, and nitrite-oxidizing bacteria from the genus Nitrospira. Aerobic and anaerobic ammonium-oxidizing bacteria were present in similar amounts of around 20 to 30% of the biomass, whereas members of the CFB phylum were present at around 7%. Nitrite oxidizing bacteria were only present in relatively low amounts (less than 5% determined with fluorescence in situ hybridization). Data from 16S rRNA dot-blot and in situ hybridization were not in all cases congruent. FISH analysis of thin-sliced and fixed biofilm samples clearly showed that the aerobic nitrifiers were located at the top of the biofilm in an extremely high density and in alternating clusters. Anammox bacteria were exclusively present in the lower half of the biofilm, whereas CFB-type filamentous bacteria were present throughout the biofilm. The structure and composition of these biofilms correlated very nicely with the proposed physiological functional separations in ammonium conversion.
在瑞士科利肯的一个危险废物填埋场，采用旋转生物接触器（RBC）处理富含铵（高达500 mg NH4(+)-N/L）但有机碳含量低的渗滤液时，观察到了大量的氮损失。对RBC上生物膜中微生物群落的组成和空间结构进行了分析，特别关注了好氧铵和亚硝酸盐氧化细菌以及厌氧铵氧化菌的存在情况。厌氧铵氧化（anammox）是指铵与亚硝酸盐氧化生成N2的过程。首先，通过对克隆的PCR扩增16S rDNA片段进行测序来确定生物膜群落的多样性。这揭示了一些非常不寻常的16S rDNA序列，但与已知的铵或亚硝酸盐氧化细菌相关的序列很少。通过用已知的系统发育探针进行荧光原位杂交以及将相同探针与从生物膜样品中纯化的总RNA进行斑点杂交来分析生物膜样品，发现构成生物膜的主要微生物群体是欧洲亚硝化单胞菌/嗜养亚硝化单胞菌组的铵氧化细菌、“斯图加特库氏菌（Candidatus Kuenenia stuttgartiensis）”类型的厌氧铵氧化细菌、拟杆菌门的丝状细菌以及硝化螺菌属的亚硝酸盐氧化细菌。好氧和厌氧铵氧化细菌的数量相似，约占生物量的20%至30%，而CFB门的成员约占7%。亚硝酸盐氧化细菌的数量相对较少（荧光原位杂交测定小于5%）。16S rRNA斑点杂交和原位杂交的数据在所有情况下并不完全一致。对薄切片和固定生物膜样品的FISH分析清楚地表明，好氧硝化菌以极高的密度交替成簇地位于生物膜的顶部。厌氧铵氧化菌仅存在于生物膜的下半部分，而CFB型丝状细菌则存在于整个生物膜中。这些生物膜的结构和组成与铵转化中提出的生理功能分离非常吻合。
