废水生物强化中基因工程菌的流失和环境生存状况研究

Leakage and Survival of Genetically Engineered Microorganism in the Environment Applied for Wastewater Bioaugmentation Treatment

在废水生物强化处理中,基因工程菌从生物反应器向环境的流失会造成潜在生态风险.在传统活性污泥法反应器(CAS)和膜-生物反应器(MBR)中,考察了1株降解阿特拉津基因工程菌的流失和流失后在模拟自然环境中的生存状况.结果表明,基因工程菌在接种初期从反应器中流失的密度最大.在接种密度为1010CFU/mL时,CAS的最大流失密度接近接种密度,MBR的最大流失密度仅有102CFU/mL.在模拟自然环境中,流失密度是决定基因工程菌生存状况的主要因素.在CAS出水1010CFU/mL流失密度下,高种群密度基因工程菌在水体和土壤中生存时间较长(30 d以上),潜在生态风险较高;在MBR出水102CFU/mL流失密度下,基因工程菌在水体和土壤中很快衰亡,潜在生态风险较小.环境条件对基因工程菌生存状况具有影响,提高土壤的含水率、有机质含量以及环境选择压力的存在有利于基因工程菌生存.

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.