一种能同时固定CO_2和N_2的微生物——兼性固CO_2、N_2菌的分离鉴定及其验证实验

Isolation,identification and validation of the facultative fixed carbon and nitrogen bacteria:A type of microorganisms that can fix CO_2 and N_2 at the same time

"温室效应"日趋严重,生物固碳特别是微生物固碳将发挥独特的作用.固定N2的微生物固氮菌和固定CO2的微生物固碳菌早已被研究和发现,但能同时固定大气中的CO2、N2并以CO2、N2分别为碳、氮源的微生物至今未见报道,本研究称之为兼性固CO2、N2菌.研究通过固碳菌、固氮菌培养基的优化组合出无碳、氮培养基(分别以空中的CO2、N2为碳源和氮源);通过无氮碳源的兼性固碳氮菌培养基进行分离,筛选分离到一株分别以CO2和N2为碳源和氮源.通过对该菌株的生长特性和固碳酶活性及固氮酶活性进行测定;利用PCR和琼脂糖凝胶电泳技术检测到该菌含有固碳酶RubisCO中cbbL基因及固氮酶nifH基因片段的特异性条带;对该菌进行对照验证实验证明该菌能同时固定空气中的CO2和N2并分别以CO2和N2为碳源和氮源;最后对其形态观察和16SrRNA全序列分析证明该菌株HSJ隶属于链霉菌.

Currently, greenhouse effect becomes more and more serious, and biological carbon-fixing, especially microbial biological carbon-fixing, can play a unique role in curbing the greenhouse effect. The N2-fixing microbial azotobacter and the CO2-fixing bacteria have been discovered for years. However, there is few report about microprganisms that can fix CO2 and N2 simultaneously while taking CO2 and N2 separately as microbial carbon and nitrogen sources. Such a microorganism was defined as facultative CO2 and N2-fixing bacteria in this study. A carbon and nitrogen-free medium was optimized by carbon-fixing medium and nitrogen-fixing medium. A strain of CO2 and N2 as the carbon source and nitrogen source, respectively, was isolated by a nitrogen and carbon-free culture medium and was labeled as HSJ. In addition, the HSJ＇s characteristics of carbon fixation enzyme activity and nitrogenase activity was determined. The HSJ with a carbon fixation enzyme specificity of cbbL gene stripe （cbbL in RubisCO genes） and nitrogen-fixing enzyme specificity of nifH gene stripe was detected by PCR and agarose gel electrophoresis. To testify fixation of CO2 and N2 in the air simultaneously with CO2 and N2 separately as the carbon and nitrogen sources, validation testing of the bacterium HSJ was carried out. The observation morphology and sequence analysis of 16S rDNA of the HSJ is subordinate to the strains of Streptomyces.