ABSTRACT
Azo dyes, which are widely used in the textile industry, exhibit significant toxic characteristics for the environment and the human population. Sequential anaerobic–aerobic reactor systems are efficient for the degradation of dyes and the mineralization of intermediate compounds; however, little is known about the composition of the microbial communities responsible for dye degradation in these systems. 454-Pyrosequencing of the 16S rRNA gene was employed to assess the bacterial biodiversity and composition of a two-stage (anaerobic–aerobic) pilot-scale reactor that treats effluent from a denim factory. The anaerobic reactor was inoculated with anaerobic sludge from a domestic sewage treatment plant. Due to the selective composition of the textile wastewater, after 210 days of operation, the anaerobic reactor was dominated by the single genus Clostridium, affiliated with the Firmicutes phylum. The aerobic biofilter harbored a diverse bacterial community. The most abundant phylum in the aerobic biofilter was Proteobacteria, which was primarily represented by the Gamma, Delta and Epsilon classes followed by Firmicutes and other phyla. Several bacterial genera were identified that most likely played an essential role in azo dye degradation in the investigated system.
Acknowledgements
We thank the CENAPAD/Department of Mechanical Engineering, UFPE – Recife for providing the computing resources for the data analysis via Qiime.
Disclosure statement
No potential conflict of interest was reported by the authors.
ORCiD
Thorsten Köchling http://orcid.org/0000-0002-8505-7764
Antônio Djalma Nunes Ferraz Jr http://orcid.org/0000-0001-9700-411X
Lourdinha Florencio http://orcid.org/0000-0002-2186-7493
Mario Takayuki Kato http://orcid.org/0000-0001-8733-5660
Sávia Gavazza http://orcid.org/0000-0002-4433-7735