Open AccessMolecular microbial diversity in a nitrifying reactor system without sludge retention
Author(s) -
Logemann Susanne,
Schantl Julia,
Bijvank Saskia,
Loosdrecht Mark,
Kuenen J.Gijs,
Jetten Mike
Publication year - 1998
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.1998.tb00540.x
Subject(s) - nitrosomonas , biology , 16s ribosomal rna , temperature gradient gel electrophoresis , microbiology and biotechnology , nitrifying bacteria , bacteria , nitrosomonas europaea , ammonia , microorganism , library , activated sludge , microbial population biology , ribosomal rna , sewage treatment , environmental chemistry , chromatography , nitrification , nitrite , biochemistry , gene , nitrogen , ecology , chemistry , genetics , waste management , organic chemistry , nitrate , engineering
Recently, the single reactor system for high activity ammonia removal over nitrite (SHARON) process was developed for the removal of ammonia from wastewater with high ammonia concentrations. In contrast to normal systems, this nitrifying reactor system is operated at relatively high temperatures (35°C) without sludge retention. Classical methods to describe the microbial community present in the reactor failed and, therefore, the microorganisms responsible for ammonia removal in this single reactor system were investigated using several complementary molecular biological techniques. The results obtained via these molecular methods were in good agreement with each other and demonstrated successful monitoring of microbial diversity. Denaturing gradient gel electrophoresis of 16S rRNA PCR products proved to be an effective technique to estimate rapidly the presence of at least four different types of bacteria in the SHARON reactor. In addition, analysis of a 16S rRNA gene library revealed that there was one dominant (69%) clone which was highly similar (98.8%) to Nitrosomonas eutropha . Of the other clones, 14% could be assigned to new members of the Cytophaga/Flexibacter group. These data were qualitatively and quantitatively confirmed by two independent microscopic methods. The presence of about 70% ammonia oxidizing bacteria was demonstrated using a fluorescent oligonucleotide probe (NEU) targeted against the 16S rRNA of the Nitrosomonas cluster. Electron microscopic pictures showed the typical morphology of ammonia oxidizers in the majority of the cells from the SHARON reactor.