Diversity and distribution of autotrophic microbial community along environmental gradients in grassland soils on the Tibetan Plateau
Diversity and distribution of autotrophic microbial community along environmental gradients in grassland soils on the Tibetan Plateau
复制标题
青藏高原草地土壤自养微生物群落多样性及其沿环境梯度的分布
DOI：
10.1007/s00253-015-6723-x
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发表时间：
2015-10-01
影响因子：
5
通讯作者：
Xia, Pinhua
中科院分区：
文献类型：
--
作者：
Guo, Guangxia;Kong, Weidong;Xia, Pinhua
土壤微生物自养菌在陆地生态系统CO2固定中发挥着重要作用，特别是在青藏高原等具有低温高紫外线特征的植被限制型生态系统中。然而，土壤微生物自养群落及其驱动因素仍然不太了解。研究了青藏高原高寒草地土壤微生物自养群落的结构、变化及其驱动因子沿着海拔梯度（海拔4400-5100 m）的变化。通过定量PCR、末端限制性片段长度多态性（T-RFLP）和cbbL基因的克隆/测序对自养微生物群落进行表征，cbbL基因编码CO2固定蛋白核酮糖-1，5-二磷酸羧化酶/加氧酶（RubisCO）的大亚基。观察到高cbbL基因丰度和高RubisCO酶活性，并且两者都随着海拔的增加而显著增加。通径分析表明，土壤RubisCO酶主要来源于微生物自养菌，其活性受土壤含水量、温度和NH 4+含量的间接驱动。土壤自养微生物群落结构随海拔高度沿着发生显著变化，并受土壤温度、含水量、养分和植物类型的共同驱动。自养微生物群落以细菌性自养菌为主，隶属于根瘤菌目、伯克霍尔德菌目和放线菌目。这些自养生物已经被很好地证明可以降解有机物;因此，代谢的多样性可能是微生物自养生物在恶劣环境中生存的关键策略。研究结果表明，高寒草地土壤中存在丰富的微生物自养菌群，具有较高的CO2固定潜力，为确定土壤微生物群落的主要驱动因子及其生态功能提供了一种新的模式。
Soil microbial autotrophs play a significant role in CO2fixation in terrestrial ecosystem, particularly in vegetation-constrained ecosystems with environmental stresses, such as the Tibetan Plateau characterized by low temperature and high UV. However, soil microbial autotrophic communities and their driving factors remain less appreciated. We investigated the structure and shift of microbial autotrophic communities and their driving factors along an elevation gradient (4400–5100 m above sea level) in alpine grassland soils on the Tibetan Plateau. The autotrophic microbial communities were characterized by quantitative PCR, terminal restriction fragment length polymorphism (T-RFLP), and cloning/sequencing ofcbbLgenes, encoding the large subunit for the CO2fixation protein ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). HighcbbLgene abundance and high RubisCO enzyme activity were observed and both significantly increased with increasing elevations. Path analysis identified that soil RubisCO enzyme causally originated from microbial autotrophs, and its activity was indirectly driven by soil water content, temperature, and NH4+content. Soil autotrophic microbial community structure dramatically shifted along the elevation and was jointly driven by soil temperature, water content, nutrients, and plant types. The autotrophic microbial communities were dominated by bacterial autotrophs, which were affiliated withRhizobiales,Burkholderiales, andActinomycetales. These autotrophs have been well documented to degrade organic matters; thus, metabolic versatility could be a key strategy for microbial autotrophs to survive in the harsh environments. Our results demonstrated high abundance of microbial autotrophs and high CO2fixation potential in alpine grassland soils and provided a novel model to identify dominant drivers of soil microbial communities and their ecological functions.