[Leakage and survival of genetically engineered microorganism in the environment applied for wastewater...

Genetically engineered microorganism (GEM) leaking from bioreactors to natural environment will lead to potential ecological risk when applied for wastewater bioaugmentation treatment. An atrazine-degrading GEM was used in a conventional activated sludge bioreactor (CAS) and a membrane bioreactor (MBR) to investigate leaking density of GEM. in the effluent. Survival of GEM in the simulated natural environments after leakage was also explored. The results showed that the maximum leakage happened at the initial time of GEM inoculation. When inoculating density was 10(10) CFU/mL, the maximum leaking density from CAS was close to inoculating density as well as the maximum leaking density from MBR was only 10(2) CFU/mL. Leaking density was the key factor influencing GEM survival in the simulated environments. When leaking density from CAS reached to 10(10) CFU/mL, GEM with high density would survive in the simulated water and soil environments for a long time (more than 30 d), which would lead to high potential ecological risk. On the contrary, when leaking density from MBR was 10(2) CFU/mL, GEM would disappear quickly in the simulated environments, which meant low potential ecological risk. Environmental conditions also affected GEM survival. Increasing water content and organic compounds content of soil as well as creating environmental selective pressure (adding atrazine) were profitable for GEM survival.