Evaluation of the biorisk on the use of microorganisms for bioremediation in the environment

为了准确评估使用微生物（包括基因工程微生物）对污染土壤/水环境进行生物修复的生物风险，通过实验研究和模型模拟积累和系统化科学信息。在第一年，重点讨论了外源微生物基因向病原体等有害微生物水平转移的生物风险并利用微宇宙模型系统研究了影响基因水平转移频率的因素：1.引入自然环境的GEMs的存活率，2.具有转移基因工程DNA序列（GEDS）潜力的可传递质粒的存在，3.质粒转移的频率和影响因素。结果表明：1.引入土壤和水生微宇宙的GEMs数量立即减少，主要原因是与土著微宇宙的竞争 ...更多信息 2.在自然环境中存在一定数量的具有tra基因的微生物，因此具有转移GEDS的能力; 3. GEDS可以转移到广泛的土著微生物中。这些结果表明，GEDS可以转移到土著微生物时，具有GEDS的GEM被释放到环境中。在第二年，通过共轭作用研究了土壤水分迁移的可能性，利用土壤微宇宙详细分析了各种环境因子对土壤水分迁移频率的影响，并对土壤水分迁移行为进行了模型分析。4.在真实的生物修复现场考察了外源微生物的行为及其对土壤微生物群落的影响。结果如下：1.在土壤环境中进行接合转移的可能性比在最佳实验室条件下低得多; 2.接合转移的频率受土壤有机碳、金属和水分含量的影响; 3.接合转移的行为可用修正的质量作用模型来描述，4.在真实的原油和二恶英污染土壤的生物修复过程中，外源微生物数量迅速减少，未观察到不良影响。少

For the accurate assessment of biorisk on the use of microorganisms including genetically engineered microorganisms (GEMs) for the bioremediation of polluted soil/aquatic environment, scientific information was accumulated and systemized through experimental investigations and model simulations.In the first year, biorisks on the horizontal transfer of the genes derived from exogenously introduced microorganisms to the indigenous harmful microorganisms such as pathogens were focused and investigated the factors which decide the frequency of the horizontal gene transfer as follows using model microcosm systems : 1.Survival of the GEMs introduced into natural environment, 2.Existence of the transmissible plasmids which have potential to transfer genetically engineered DNA sequences(GEDS), 3.Frequency and factors of plasmid transfer. The results were as follows : 1.GEMs introduced into soil and aquatic microcosms immediately decreased mainly because of the competition with indigenous micro … More organisms but after that survived at low level for relatively long periods, 2.There existed a certain level of microorganisms possessing tra gene, and therefore, the ability to transfer GEDS in natural environment, 3.GEDS could be transferred to wide range of indigenous microorganisms. These results implied that the GEDS can be transferred to indigenous microorganisms when GEMs possessing GEDS are released into the environment. The frame of the model to explain the behavior of the GEDS was also developed.In the second year, 1.The transferability of the GEDS by conjugation, 2.The influence of the various environmental factors on the frequency of the transfer were evaluated in detail using soil microcosms, and 3.The behavior of the GEDS was analyzed by model. Furthermore, 4.The behavior of exogenously introduced microorganisms and the influence on indigenous microbial community were evaluated at the real bioremediation fields. The results were as follows : 1.The possibility of the conjugative gene transfer was considerably lower in the soil environments than under the optimal laboratory condition, 2.The frequency of the transfer was influenced by the levels of the organic carbons, metals, and water contents, 3.The behavior of GEDS by conjugative transfer could be expressed by the modified mass action model, and 4.The exogenously introduced microorganisms decreased rapidly and no adverse effects were observed during bioremediation of real crude oil and dioxin contaminated soils. Less