基于哈尔滨不动细菌去除低温地下水中硝酸盐的机理研究及优势菌群构建

In China, it is common that nitrate in ground water is over the standard. Because the temperature of ground water is normally low, it is difficult for biological methods to effectively remove nitrate from ground water. The novel species, Acinetobacter harbinensis, is the bacteria that can grow at low temperature. The optimal growth temperature for Acinetobacter harbinensis is 8-20 ℃. It can grow quickly at 2 ℃. The existed results show that Acinetobacter harbinensis can utilize organic carbon as sole carbon source. It also can use CO2 as sole carbon source. It might belong to the facultative autotrophic bacteria. When Acinetobacter harbinensis is used in source water treatment, the nitrate removal efficiency is higher than 95% at 6-8℃. The application of Acinetobacter harbinensis provides a novel way for nitrate removal from ground water at low temperature. In this project, the CO2 fixation pathway and autotrophic characteristics of Acinetobacter harbinensis will be investigated. The nitrate reduction pathway and the electron donors of Acinetobacter harbinensis will be confirmed. The chemical reaction equation and co-metabolism model of CO2, organic carbon and NO3- will be constructed for Acinetobacter harbinensis. The mechanism of nitrate reduction of Acinetobacter harbinensis will be illustrated. The preponderant microbial consortium based on Acinetobacter harbinensis will be constructed by traditional microbiology methods, ecological and mathematical model, and AQUASIM software platform. The preponderant microbial consortium will be used in effectively and stably removing nitrate from ground water at low temperature with high efficiency and stability. The optimal application condition and the stable characteristics of the constructed preponderant microbial consortium will be studied. The results of this project will solve the key theories and technology for applying Acinetobacter harbinensis in nitrate removal from ground water at low temperature, which will be important for guaranteeing the drinking water safety for Chinese citizens.

我国地下水普遍存在硝酸盐超标问题，由于地下水温较低，给生物处理除硝酸盐带来困难。新菌种——哈尔滨不动细菌最适生长温度为8-20℃，在2℃下可快速生长，已有研究表明哈尔滨不动细菌既可利用有机物，也可利用CO2为唯一碳源进行生长，为兼性自养菌，在6-8℃对水源水中硝酸盐的去除率可达95%以上，应用哈尔滨不动细菌可为低温地下水除硝酸盐提供新途径。本项目将通过明确哈尔滨不动细菌的CO2固定途径和自养特征；确定哈尔滨不动细菌的硝酸盐还原途径和电子供体，建立其CO2、有机碳和NO3-的化学反应方程和共代谢模型，阐明哈尔滨不动细菌的硝酸盐还原机理；基于哈尔滨不动细菌，结合微生物学方法、生态数学模型和AQUASIM软件平台，构建高效、稳定的低温地下水除硝酸盐优势菌群，明确优势菌群的最佳应用条件和稳定特征；可有效解决哈尔滨不动细菌去除低温地下水中硝酸盐的关键理论与技术问题，对保障居民供水安全具有重要意义。

我国地下水普遍存在硝酸盐超标问题，由于地下水温较低，给生物处理除硝酸盐带来困难。本项目分离获得了低温好氧反硝化菌F5-6、Y5-11、Y24-6和Y39-6，经过形态特征、生理生化特征和基因学特征鉴定，F5-6为一株嗜冷菌，Y5-11、Y24-6和Y39-6为假单胞菌，研究成果已申请国家发明专利CN201910073841.8、CN201910073844.1和CN201910073209.3。由于菌株Y5-11、Y24-6和Y39-6可以在好氧条件下利用无机碳进行反硝化，属于生物氮代谢的新类型，称其为低温好氧-兼性自养反硝化菌，本项目重点针对低温好氧-兼性自养反硝化菌，建立了自养反硝化动力学模型，研究了自养反硝化代谢途径；分析了环境因素对低温好氧-兼性自养反硝化菌去除硝酸盐的影响；基于哈尔滨不动细菌和低温好氧-兼性自养反硝化菌构建了优势菌群，并分析了优势菌群去除地下水中硝酸盐的稳定性。菌株Y5-11、Y24-6和Y39-6的自养反硝化动力学模型与莫诺方程高度拟合，µmax和Ks分别为198.227·h-1、163.036·h-1、195.556·h-1和134.997 mg/L、94.627 mg/L、174.922 mg/L；菌株Y39-6在15℃时对硝酸盐的去除效果最好，其自养反硝化代谢机理为自养条件下固定外界的CO2生成内源有机碳，进行异化硝酸盐还原生成NH4+-N，NH4+-N会及进一步与内源有机碳进行合成反应，促使菌株生长，Y39-6同时还会利用内源有机碳进行反硝化，最终将NO3--N转化为N2从水中去除；将哈尔滨不动细菌、Y24-6和Y39-6以1:1:1的比例构建优势菌群，在自养条件下进行生物增强形成的生物量最高，用于处理低温地下水时，运行7天后仍有良好的稳定性。本项目成果可为开发低温地下水除硝酸盐的新技术提供理论依据。