Analysis of microbial community in atrazine treatment systems bioaugmented by genetically engineered microorganism

Abstract

Atrazine removal in membrane bioreactor (MBR) and conventional activated sludge reactor (CAS) bioaugmented by genetically engineered microorganism (GEM) was investigated. PCR-DGGE was used to analyze microbial community variation of both bioreactors in different running stages. The results indicated that high removal efficiency of atrazine was obtained in both bioreactors bioaugmented by GEM. The average removal efficiencies of atrazine reached up to 88.6% in MBR and 85.3% in CAS. Atrazine removal bioaugmented by GEM would be helpful to maintain sludge bioactivity in both bioreactors. The performance of MBR was better than CAS. The GEM density decreased quickly in both bioreactors after GEM inoculation and then became stable. The stable GEM densities in MBR and CAS were 2.1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> CFU/mL and 1.7×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> CFU/mL, respectively. PCR-DGGE analysis showed microbial community variation in different running stages of both bioreactors. The biodiversity and stability of microbial community decreased in the presence of atrazine exposure and recovered after efficient atrazine removal. MBR seemed better than CAS to maintain biodiversity and stability of microbial community.