非光合固碳微生物的碳源组合优化

二氧化碳(CO_2)过量排放而引起的全球变暖是目前全球面临的重大环境问题。微生物固碳是实现二氧化碳资源利用的一种重要方式。探索无需光照的高效固碳微生物对于更广泛环境条件下的微生物固碳具有重要意义。在从全球各大海域筛选富集出非光合微生物茵群的基础上,本文构建了在不同的电子供体条件下(铵和氢气)促进非光合微生物茵群生长的最佳混合碳源组合,得到如下结果:在以NH_4~+为电子供体的条件下,优化后的碳源组合为374.24 mgC/L碳酸钠(Na_2CO_3),54.76 mgC/L碳酸氢钠(NaHCO_3)和0 mgC/LCO_2时,最佳响应值TOC为3.06 mg/L。最佳响应值TOC低于以Na_2CO_3为单一碳源时,但高于以CO_2或NaHCO_3为单一碳源时;在以H_2为电子供体条件下,使用优化后的混合碳源为0.26 mg/L Na_2CO_3、0.59mg/L NaHCO_3和71.48mL/L CO_2时,非光合微生物菌群的固碳效率可达27.62 mg/L,较以CO_2为单一碳源提高35%左右。这可能意味着有H_2条件下非光合微生物菌群中的微生物可能以羟基丙酸固碳途径为主,而且多条固碳途径均能被混合菌群利用。

Optimization of carbon source in process of C0_2 fixation by non-photosynthetic microbial communities

Global warming caused by excessive emission of CO_2 is a major environmental problem currently. CO2fixing by microbial communities is a very important part of C0_2 resource utilization. Therefore, it is necessary to isolate highly efficient CO_2 fixing microorganisms that do not require light or hydrogen to enable a wider range of applications. Non- photosynthetic bacteria had done from some of the world＇s ocean by premier experiments. This research was based on the premier experiments and took the non-photosynthetic microbial communities separated from seawater as object to construct the optimal mix carbon source system to promote growth of microbacteria under the condition of different electron donors. When the optimal carbon source components were 374.24 mgC/L Na_2CO_3, 54.76 mgC/L NaHCO_3 and 0 mgC/L CO_2 with NH4 ＋ as electron donor, the predicted max TOC was 3.06 mg/L. The value of the predicted max TOC was lower than that of using the Na_2CO_3 as single carbon source, but higher than that of using the CO_2 or NaHCO_3 as single carbon source respectively. When the optimal carbon source components was 0.26 mg/L Na_2C0_3, 0.59 mg/L NaHCO_3 and 71.48 mL/L CO_2 with H_2 as electron donor, the carbon fixation efficiency by non-photosynthetic microbial communities was up to 27.62 mg/L, which increased by about 35% comparing with CO2 as the sole carbon source. The results suggested that hydroxyprepionate cycle might be the main carbon fixing cycle and all the six carbon fixing cycles could be used by non-photosynthetic microbial communities with H_2.