反硝化菌株DA-1的脱氮研究

菌株DA-1被发现能在好氧和厌氧环境中将硝酸盐转化为气态氮。在以NO3-为唯一氮源的条件下研究了碳源、C/N和pH值对菌株DA-1好氧和厌氧反硝化脱氮的影响。结果表明:同等条件下,48 h内菌株DA-1的厌氧脱氮效率高于好氧脱氮率;菌株DA-1能在好氧和厌氧条件下利用乙酸、柠檬酸以及葡萄糖进行细胞增殖和反硝化。在厌氧条件下,三者作为碳源时的反硝化效率分别为(34.04±0.15)%、(22.72±0.32)%和(11.32±0.06)%,均低于好氧条件下的(25.38±0.14)%、(17.52±0.11)%和(8.06±0.01)%。2种条件下均是乙酸为碳源时反硝化效率最高。而丁二酸仅能在厌氧环境中作为电子供体参与反硝化反应。C/N越高越有利于菌株DA-1的厌氧反硝化,当C/N为10时,反硝化效率最高为(35.06±0.19)%。而在好氧条件下,菌株反硝化效率随着C/N的升高,先升高再降低,当C/N为8时,反硝化效率最高;好氧和厌氧脱氮的最适pH值为7.0。体系偏酸或者偏碱都会造成菌株DA-1脱氮效率的降低并出现亚硝酸盐累积。厌氧环境中pH=5.0时累积的亚硝酸盐浓度高达(8.95±2.05)mg/mL。

Nitrogen Removal Characteristics of Denitrifying Bacterium Strain DA-1

Bacterium strain DA-1 exhibits an ability to convert nitrate to gaseous nitrogen compounds under both aerobic and anaerobic conditions.Using NO3-as a sole nitrogen source,aerobic and anaerobic nitrogen removal by strain DA-1 was analyzed in the relation to carbon sources,carbon-to-nitrogen ratio and pH value.In both two conditions,strain DA-1 could utilize sodium acetate,citric acid and glucose for growth and denitrification.When acetate,citrate and glucose were provided as carbon sources,the percentages of TN removed within 48 h were(34.04±0.15)%,(22.72±0.32)% and(11.32±0.06)% in anerobic conditions,and(25.38±0.14)%,(17.52±0.11)% and(8.06±0.01)% in aerobic conditions respectively.The strain showed the highest nitrogen removal efficiency in sodium acetate medium.Despite not supporting cell proliferation,succinic acid could be used as electron acceptor for denitrification under anaerobic conditions.As C/N ratio of the medium increased,the ability of strain DA-1 transforming nitrate to gaseous nitrogen compounds was enhanced in anerobic denitrifcation process and(35.06±0.19)% of TN was removed.In aerobic process,strain DA-1 removed the most TN at C/N of 8: 1.The optimal pH value for denitrification was 7.0 in both two conditions.Nitrite accumulated in the anaerobic medium of pH 5.0,and its concentration reached(8.95±2.05) mg/mL.