Wang Qun-Yan, Wu Xiao-Hong, Zhu Zhen-Ke, Yuan Hong-Zhao, Sui Fang-Gong, Ge Ti-da, Wu Jin-Shui
Collage of Resources and Environment, Qingdao Agriculture University, Qingdao 266109, China.
Collage of Life Science and Technology, Central South University of Forestry and Technology, Changsha 410018, China.
Huan Jing Ke Xue. 2016 Oct 8;37(10):3987-3995. doi: 10.13227/j.hjkx.2016.10.042.
Autotrophic bacteria can assimilate atmospheric carbon dioxide (CO) and convert CO into organic carbon. The CO fixation by autotrophic bacteria is important for the improvement of carbon sequestration in agricultural soils. However, the effect of soil texture on autotrophic CO fixation bacteria and their CO fixation capacity is still unknown. Here, two paddy soils with different textures (loamy clay soil and sand clay loam soil) were incubated with continuous C-CO in a glass chamber. The two soils were developed from the same parent. At the end of 110 days incubation, the C-CO incorporated in soil organic carbon (C-SOC), microbial biomass carbon (C-MBC) and dissolved organic carbon (C-DOC) were measured to explore the effects of soil texture on the autotrophic bacterial CO fixation rates. The effect of soil texture on the composition and diversity of autotrophic CO fixation bacterial community was investigated using cloning and sequencing of the gene, which encodes ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO) in the Calvin cycle. The results showed that the average contents of C-SOC, C-MBC and C-DOC were 133.81, 40.16 and 8.10 mg·kg in loamy clay soil, respectively, which were significantly higher than their corresponding contents in sand clay loam soil (<0.05). This suggested that soil texture not only affected the amounts of autotrophic bacteria CO fixation but also had an effect on the transformation of microbial assimilated C in soil. The gene libraries of two soils were significantly different as revealed by libshuff analyses (<0.05). Phylogenetic analysis showed that sequences from the loamy clay soil were closely affiliated with known cultures such as , , , sp.and sp., whereas these sequences belonging to the sand clay loam soil were related to branching lineages originating from and .Rarefaction curve, clone library coverage and diversity index analysis based on bacterial clone libraries indicated that the loamy clay soil had higher gene diversity compared to the sand clay loam soil. These results suggested that soil texture had a pronounced effect on the composition and diversity of autotrophic CO fixation bacterial communities. The higher clay content, nutrient availability and cation exchange capacity may stimulate the growth and activity of autotrophic bacteria, and result in the higher amounts of C in loamy clay soil. These data broaden the understanding and knowledge of mechanisms of microbial carbon fixation and their influencing factors in agricultural soils.
自养细菌可以吸收大气中的二氧化碳（CO₂）并将其转化为有机碳。自养细菌的CO₂固定对于提高农业土壤中的碳固存具有重要意义。然而，土壤质地对自养CO₂固定细菌及其CO₂固定能力的影响仍然未知。在此，将两种质地不同的水稻土（粘壤土和砂质粘壤土）置于玻璃室中用¹³C-CO₂进行连续培养。这两种土壤由同一母质发育而来。在培养110天后，测量了土壤有机碳（C-SOC）、微生物生物量碳（C-MBC）和溶解有机碳（C-DOC）中掺入的¹³C-CO₂，以探究土壤质地对自养细菌CO₂固定速率的影响。利用对卡尔文循环中编码核酮糖-1,5-二磷酸羧化酶/加氧酶（RubisCO）的基因进行克隆和测序，研究了土壤质地对自养CO₂固定细菌群落组成和多样性的影响。结果表明，粘壤土中C-SOC、C-MBC和C-DOC的平均含量分别为133.81、40.16和8.10 mg·kg⁻¹，显著高于砂质粘壤土中的相应含量（P<0.05）。这表明土壤质地不仅影响自养细菌的CO₂固定量，而且对土壤中微生物同化碳的转化也有影响。通过文库洗牌分析（P<0.05）表明，两种土壤的基因文库存在显著差异。系统发育分析表明，粘壤土中的序列与已知培养物如[具体菌属1]、[具体菌属2]、[具体菌属3]、[具体菌属4]和[具体菌属5]密切相关，而砂质粘壤土中的这些序列与源自[具体菌属6]和[具体菌属7]的分支谱系相关。基于细菌[具体基因]克隆文库的稀释曲线、克隆文库覆盖率和多样性指数分析表明，粘壤土的[具体基因]多样性高于砂质粘壤土。这些结果表明，土壤质地对自养CO₂固定细菌群落的组成和多样性有显著影响。较高的粘土含量、养分有效性和阳离子交换容量可能会刺激自养细菌的生长和活性，从而导致粘壤土中碳含量较高。这些数据拓宽了对农业土壤中微生物碳固定机制及其影响因素的理解和认识。
