Kuske Cheryl R, Ticknor Lawrence O, Miller Mark E, Dunbar John M, Davis Jody A, Barns Susan M, Belnap Jayne
Biosciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Appl Environ Microbiol. 2002 Apr;68(4):1854-63. doi: 10.1128/AEM.68.4.1854-1863.2002.
Soil bacteria are important contributors to primary productivity and nutrient cycling in arid land ecosystems, and their populations may be greatly affected by changes in environmental conditions. In parallel studies, the composition of the total bacterial community and of members of the Acidobacterium division were assessed in arid grassland soils using terminal restriction fragment length polymorphism (TRF, also known as T-RFLP) analysis of 16S rRNA genes amplified from soil DNA. Bacterial communities associated with the rhizospheres of the native bunchgrasses Stipa hymenoides and Hilaria jamesii, the invading annual grass Bromus tectorum, and the interspaces colonized by cyanobacterial soil crusts were compared at three depths. When used in a replicated field-scale study, TRF analysis was useful for identifying broad-scale, consistent differences in the bacterial communities in different soil locations, over the natural microscale heterogeneity of the soil. The compositions of the total bacterial community and Acidobacterium division in the soil crust interspaces were significantly different from those of the plant rhizospheres. Major differences were also observed in the rhizospheres of the three plant species and were most apparent with analysis of the Acidobacterium division. The total bacterial community and the Acidobacterium division bacteria were affected by soil depth in both the interspaces and plant rhizospheres. This study provides a baseline for monitoring bacterial community structure and dynamics with changes in plant cover and environmental conditions in the arid grasslands.
土壤细菌是干旱陆地生态系统初级生产力和养分循环的重要贡献者，其种群数量可能会受到环境条件变化的极大影响。在平行研究中，利用对从土壤DNA中扩增出的16S rRNA基因进行末端限制性片段长度多态性（TRF，也称为T-RFLP）分析，评估了干旱草原土壤中细菌群落的总体组成以及嗜酸菌门成员的组成。比较了与本地丛生禾本科植物膜稃针茅和詹姆斯针茅的根际、入侵一年生禾本科植物硬雀麦以及蓝藻土壤结皮定殖的间隙相关的细菌群落在三个深度的情况。当用于重复的田间尺度研究时，TRF分析有助于识别不同土壤位置细菌群落的大规模、一致差异，克服土壤自然微尺度异质性的影响。土壤结皮间隙中细菌群落的总体组成和嗜酸菌门与植物根际的组成存在显著差异。在三种植物的根际也观察到了主要差异，对嗜酸菌门的分析最为明显。间隙和植物根际中的细菌群落总体和嗜酸菌门细菌都受到土壤深度的影响。本研究为监测干旱草原中细菌群落结构和动态随植物覆盖和环境条件的变化提供了基线。
