RESUMO
Amplified ribosomal DNA restriction analysis (ARDRA) is a simple method based on restriction endonuclease digestion of the amplified bacterial 16S rDNA. In this study we have evaluated the suitability of this method to detect differences in activated sludge bacterial communities fed on domestic or industrial wastewater, and subject to different operational conditions. The ability of ARDRA to detect these differences has been tested in modified Ludzack-Ettinger (MLE) configurations. Samples from three activated sludge wastewater treatment plants (WWTPs) with the MLE configuration were collected for both oxic and anoxic reactors, and ARDRA patterns using double enzyme digestions AluI+MspI were obtained. A matrix of Dice similarity coefficients was calculated and used to compare these restriction patterns. Differences in the community structure due to influent characteristics and temperature could be observed, but not between the oxic and anoxic reactors of each of the three MLE configurations. Other possible applications of ARDRA for detecting and monitoring changes in activated sludge systems are also discussed.
Assuntos
Bactérias/isolamento & purificação , DNA Bacteriano/genética , DNA Ribossômico/análise , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Mapeamento por Restrição , Microbiologia da Água , Aerobiose , Anaerobiose , Bactérias/genética , Bactérias/metabolismo , Biomassa , Desoxirribonuclease HpaII , Desoxirribonucleases de Sítio Específico do Tipo II , Esgotos/microbiologia , Espanha , Eliminação de Resíduos LíquidosRESUMO
A comparative analysis of 16S ribosomal DNA sequences from 18 strains belonging to different species of the genus Chlorobium has been made in order to investigate their phylogenetic relationships. All studied strains with brown pigmentation, belonging to species C. phaeobacteroides and C. phaeovibrioides, were clustered together and separated from green species. Most of the C. limicola strains formed a consistent group and were clustered next to C. tepidum. But, despite their identical morphology, C. vibrioforme strain 6030 (= DSM 260T) and C. vibrioforme strain 8327 (= DSM 263) were clearly differentiated on the basis of their 16S rDNA sequence. On the other hand, morphologically distinctive strains of C. chlorovibrioides, C. vibrioforme and C. limicola presented sequences with a high degree of similarity. Since morphological characters do not seem to be sufficient to adequately classify this group, these findings help to set up the basis for a revision of the taxonomy of the genus Chlorobium.
