Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing, China.
Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, the Netherlands.
Appl Environ Microbiol. 2021 Apr 13;87(9). doi: 10.1128/AEM.00046-21.
To maintain the beneficial effects of microbial inoculants on plants and soil, repeated inoculation represents a promising option. Until now, the impacts of one-off inoculation on the native microbiome have been explored, but it remains unclear how long and to what extent the periodic inoculations would affect the succession of the resident microbiome in bulk soil. Here, we examined the dynamic responses of plant growth, soil functions, and the resident bacterial community in the bulk soil to periodic inoculations of phosphate-solubilizing and N-fixing bacteria alone or in combination. Compared to single-strain inoculation, coinoculation better stimulated plant growth and soil nutrients. However, the benefits from inoculants did not increase with repeated inoculations and were not maintained after transplantation to a different site. In response to microbial inoculants, three patterns of shifts in the bacterial composition were observed: fold increase, fold decrease, and resilience. The periodic inoculations impacted the succession course of resident bacterial communities in bulk soil, mainly driven by changes in soil pH and nitrate, resulting in the development of three main cluster types throughout the investigation. The single and mixed inoculants transiently modulated the variation in the resident community in association with soil pH and the C/N ratio, but finally, the community established and showed resilience to subsequent inoculations. Consequently, the necessity of repeated inoculations should be reconsidered, and while the different microbial inoculants showed distinct impacts on resident microbiome succession, the communities ultimately exhibited resilience. Introducing beneficial microbes to the plant-soil system is an environmentally friendly approach to improve the crop yield and soil environment. Numerous studies have attempted to reveal the impacts of inoculation on the rhizosphere microbiome. However, little is known about the effectiveness of periodic inoculations on soil functioning. In addition, the long-term impact of repeated inoculations on the native community remains unclear. Here, we track the succession traits of the resident microbiome in the bulk soil across a growing season and identify the taxon clusters that respond differently to periodic inoculation. Crucially, we compare the development of the resident community composition with and without inoculation, thus providing new insight into the interactions between resident microbes and intruders. Finally, we conclude that initial inoculation plays a more important role in influencing the whole system, and the native microbial community exhibits traits of resilience, but no resistance, to the subsequent inoculations.
为了维持微生物接种剂对植物和土壤的有益效果，重复接种是一种很有前景的选择。到目前为止，人们已经研究了一次性接种对本地微生物组的影响，但尚不清楚周期性接种会在多长时间和多大程度上影响土壤中常驻微生物组的演替。在这里，我们研究了单独或组合接种解磷菌和固氮菌对植物生长、土壤功能和土壤中常驻细菌群落的动态响应。与单菌株接种相比，共接种更能促进植物生长和土壤养分。然而，接种剂的益处并没有随着重复接种而增加，并且在移植到不同地点后也没有得到维持。对于微生物接种剂，观察到细菌组成的三种变化模式：倍数增加、倍数减少和弹性。周期性接种会影响土壤中常驻细菌群落的演替过程，主要是由土壤 pH 和硝酸盐的变化驱动的，导致在整个研究过程中形成了三种主要的聚类类型。单接种和混合接种剂暂时改变了与土壤 pH 和 C/N 比相关的常驻群落的变异性，但最终，该群落建立起来并对随后的接种剂表现出弹性。因此，应该重新考虑重复接种的必要性，虽然不同的微生物接种剂对常驻微生物组的演替有明显的影响，但这些群落最终表现出弹性。向植物-土壤系统中引入有益微生物是一种改善作物产量和土壤环境的环保方法。许多研究试图揭示接种对根际微生物组的影响。然而，对于周期性接种对土壤功能的有效性知之甚少。此外，重复接种对本地群落的长期影响尚不清楚。在这里，我们在整个生长季节跟踪土壤中常驻微生物组的演替特征，并确定对周期性接种有不同反应的分类群聚类。至关重要的是，我们比较了有和没有接种的常驻群落组成的发展，从而为常驻微生物和入侵微生物之间的相互作用提供了新的见解。最后，我们得出结论，初始接种在影响整个系统方面发挥着更重要的作用，而本地微生物群落对随后的接种表现出弹性特征，但没有抗性。
