Soil degradation is an ecological disturbance, usually human-caused, that negatively affects the vegetation and climate of an ecosystem, particularly arid and semiarid environments. These degraded soils can be restored by using native perennial plants inoculated with specific microorganisms. We studied the changes in root growth and the rhizosphere bacterial community of mesquite seedlings (Prosopis articulata) after inoculation with the endophytic bacteria Bacillus pumilus ES4, over 3 cycles of growth in the same soil under desert climatic conditions, and found that inoculation significantly enhanced root biomass during the growth cycles but not shoot biomass or root and shoot lengths. Fluorescent in situ hybridization analysis demonstrated that B. pumilus colonized the root cap, apical meristem, and elongation zone, forming small colonies, on roots from soil-grown mesquite. Inoculation also significantly changed the bacterial community structure of rhizophere and nonrhizosphere (without plants) soils based on denaturing gradient gel electrophoresis profiles. The changes were highly stable, and the bacterial community structure was maintained throughout the experimental period and not affected by plant replacement. The 16S rRNA pyrosequencing confirmed the changes on structure of bacterial community and revealed an impact on the top taxonomic levels analyzed. The rhizospheres of inoculated plants showed a significant increase in the abundance of Proteobacteria and Acidobacteria coupled with a concomitant decrease in Actinobacteria, whereas an opposite response was observed in nonrhizospheric degraded soils. Overall, inoculation with B. pumilus reduced bacterial diversity but increased the Rhizobium population in the soil. The class Bacilli, despite B. pumilus inoculum, showed minimal variation.

中文翻译：

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接种植物促生菌诱导豆科植物幼苗根系生长和细菌根际和土壤群落变化，促进侵蚀沙漠土壤恢复

土壤退化是一种生态干扰，通常是人为造成的，它对生态系统的植被和气候产生负面影响，尤其是干旱和半干旱环境。这些退化的土壤可以通过使用接种特定微生物的本地多年生植物进行恢复。我们研究了豆科植物幼苗（Prosopis articulata）在沙漠气候条件下在同一土壤中接种内生细菌 Bacillus pumilus ES4 超过 3 个生长周期后根系生长和根际细菌群落的变化，发现接种显着增强了根系。生长周期中的生物量，但不是枝条生物量或根和枝条长度。荧光原位杂交分析表明短小芽孢杆菌定植于根冠、顶端分生组织和伸长区，形成小菌落，在土壤生长的豆科植物的根上。基于变性梯度凝胶电泳图谱，接种还显着改变了根际和非根际（无植物）土壤的细菌群落结构。变化高度稳定，细菌群落结构在整个实验期间保持不变，不受植物更替的影响。16S rRNA 焦磷酸测序证实了细菌群落结构的变化，并揭示了对分析的最高分类水平的影响。接种植物的根际显示变形菌和酸菌的丰度显着增加，同时放线菌减少，而在非根际退化土壤中观察到相反的反应。总体而言，接种 B. pumilus 减少了细菌多样性，但增加了土壤中的根瘤菌种群。尽管 B. pumilus 接种，Bacilli 类显示出最小的变异。