Plant diseases caused by fungal pathogen result in a substantial economic impact on the global food and fruit industry. Application of organic fertilizers supplemented with biocontrol microorganisms (i.e. bioorganic fertilizers) has been shown to improve resistance against plant pathogens at least in part due to impacts on the structure and function of the resident soil microbiome. However, it remains unclear whether such improvements are driven by the specific action of microbial inoculants, microbial populations naturally resident to the organic fertilizer or the physical-chemical properties of the compost substrate. The aim of this study was to seek the ecological mechanisms involved in the disease suppressive activity of bio-organic fertilizers. To disentangle the mechanism of bio-organic fertilizer action, we conducted an experiment tracking Fusarium wilt disease of banana and changes in soil microbial communities over three growth seasons in response to the following four treatments: bio-organic fertilizer (containing Bacillus amyloliquefaciens W19), organic fertilizer, sterilized organic fertilizer and sterilized organic fertilizer supplemented with B. amyloliquefaciens W19. We found that sterilized bioorganic fertilizer to which Bacillus was re-inoculated provided a similar degree of disease suppression as the non-sterilized bioorganic fertilizer across cropping seasons. We further observed that disease suppression in these treatments is linked to impacts on the resident soil microbial communities, specifically by leading to increases in specific Pseudomonas spp.. Observed correlations between Bacillus amendment and indigenous Pseudomonas spp. that might underlie pathogen suppression were further studied in laboratory and pot experiments. These studies revealed that specific bacterial taxa synergistically increase biofilm formation and likely acted as a plant-beneficial consortium against the pathogen. Together we demonstrate that the action of bioorganic fertilizer is a product of the biocontrol inoculum within the organic amendment and its impact on the resident soil microbiome. This knowledge should help in the design of more efficient biofertilizers designed to promote soil function.

中文翻译：

---

生物有机肥料刺激本土土壤假单胞菌种群，从而增强对植物病害的抑制。


由真菌病原体引起的植物病害对全球食品和水果行业造成重大经济影响。施用补充有生物防治微生物的有机肥料（即生物有机肥料）已被证明可以提高对植物病原体的抵抗力，至少部分是由于对驻留土壤微生物群的结构和功能的影响。然而，目前尚不清楚这种改进是否是由微生物接种剂的特定作用、有机肥料中自然存在的微生物种群或堆肥基质的物理化学特性驱动的。本研究的目的是寻找生物有机肥料防病活性的生态机制。为了阐明生物有机肥的作用机制，我们进行了一项实验，跟踪香蕉枯萎病和三个生长季节土壤微生物群落的变化，以响应以下四种处理：生物有机肥（含解淀粉芽孢杆菌W19），有机肥、灭菌有机肥和添加解淀粉芽孢杆菌W19的灭菌有机肥。我们发现，重新接种芽孢杆菌的灭菌生物有机肥料在整个种植季节提供了与未灭菌生物有机肥料相似程度的疾病抑制作用。我们进一步观察到，这些处理中的疾病抑制与对当地土壤微生物群落的影响有关，特别是通过导致特定假单胞菌属的增加。观察到芽孢杆菌改良剂和本地假单胞菌属之间的相关性。在实验室和盆栽实验中进一步研究了可能是病原体抑制的基础。 这些研究表明，特定的细菌类群可以协同增加生物膜的形成，并可能作为对抗病原体的对植物有益的联合体。我们共同证明，生物有机肥料的作用是有机改良剂中生物防治接种物及其对土壤微生物组影响的产物。这些知识应该有助于设计更有效的生物肥料，以促进土壤功能。