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自养微生物可同化大气中的CO2并将其转化为土壤有机碳,对提高农田土壤的碳吸收和碳储存有重要意义,然而土壤质地对自养固碳微生物功能种群及其同化碳的影响机制还不清楚.本研究选取亚热带地区同一母质发育而成的两种质地水稻土壤(壤质黏土和砂质黏壤土),通过~(14)C-CO2连续标记技术结合室内模拟培养实验,探讨土壤质地对自养微生物同化碳(~(14)C-SOC)、自养微生物截留碳(~(14)C-MBC)和自养微生物可溶性碳(~(14)C-DOC)的影响.以固碳功能基因(cbb L基因)作为指示基因,结合PCR和克隆测序技术,分析不同质地土壤自养固碳微生物群落结构和多样性的差异.结果表明,壤质黏土~(14)C-SOC、~(14)C-MBC和~(14)C-DOC平均含量分别为133.81、40.16和8.10 mg·kg-1,均显著高于砂质黏壤土~(14)C-SOC(104.95 mg·kg-1)、~(14)C-MBC(33.26 mg·kg-1)和~(14)C-DOC(4.18 mg·kg-1)平均含量(P<0.05),说明土壤质地显著影响了土壤自养微生物碳同化量以及自养微生物同化碳在土壤中的转化.稀疏曲线、细菌cbb L基因文库覆盖度以及多样性指数分析结果显示壤质黏土固碳细菌群落多样性高于砂质黏壤土.系统发育分析表明,壤质黏土细菌cbb L基因序列与Rhodoblastus acidophilus、Blastochloris viridis、Thauera humireducens、Mehylibium sp.、Variovorax sp.等具有一定的同源性,而砂质黏壤土cbb L基因序列主要与根瘤菌和放线菌同源.可见,土壤质地对自养固碳微生物群落结构和多样性产生了深刻的影响,壤质黏土中较高的黏粒含量、土壤养分含量和阳离子交换量可能有利于维持更高的自养固碳微生物多样性和活性,从而导致不同质地土壤自养微生物碳同化量及其转化存在显著差异.
Autotrophic microbes can assimilate CO2 in the atmosphere and convert it into soil organic carbon, which is of great significance to improve carbon absorption and carbon storage in farmland soil. However, the effect of soil texture on the functional populations of autotrophic carbon colonies and their assimilation carbon It is not clear yet.In this study, two paddy soils (loamy clay and sandy loamy soil) developed from the same parent material in the subtropical zone were selected to study the effect of soil Effects of texture on autotrophic microbial assimilation carbon (~ (14) C-SOC), autotrophic microbial intercalating carbon (~ (14) C-MBC) and autotrophic microbial soluble carbon (~ (Cbb L gene) was used as indicator gene and the differences of structure and diversity of soil autotrophic carbon fixation communities were analyzed by PCR and cloning sequencing.The results showed that the C-SOC (14) C-DOC and ~ (14) C-DOC were 133.81, 40.16 and 8.10 mg · kg-1, respectively, (P <0.05), indicating that the soil texture was significantly affected by the average content of ~ (14) C-DOC (4.18 mg · kg- Soil autotrophic carbon assimilation amount and autotrophic microbial assimilation carbon transformation in soil.The sparse curves, bacterial cbb L gene library coverage and diversity index analysis showed that the diversity of carbon sequestration bacteria community in loamy clay was higher than that in sandy soil The results of phylogenetic analysis showed that the sequence of cbb L gene in loamy clay loam has certain homology with Rhodoblastus acidophilus, Blastochloris viridis, Thauera humireducens, Mehylibium sp. And Variovorax sp. And rhizobia and actinomycetes.It can be seen that texture of the soil has a profound impact on the structure and diversity of autotrophic carbon colonies, higher clay content, soil nutrient content and cation exchange capacity in loamy clay Which is conducive to maintaining a higher diversity and activity of autotrophic carbon microbes, leading to significant differences in carbon assimilation amount and transformation of autotrophic microbes in different soil textures.