College of Life Sciences, Nankai University, Tianjin, 300071, China.
Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands.
Microb Biotechnol. 2019 May;12(3):459-471. doi: 10.1111/1751-7915.13365. Epub 2019 Jan 7.
Soil-dwelling entomopathogenic nematodes (EPNs) kill arthropod hosts by injecting their symbiotic bacteria into the host hemolymph and feed on the bacteria and the tissue of the dying host for several generations cycles until the arthropod cadaver is completely depleted. The EPN-bacteria-arthropod cadaver complex represents a rich energy source for the surrounding opportunistic soil fungal biota and other competitors. We hypothesized that EPNs need to protect their food source until depletion and that the EPN symbiotic bacteria produce volatile and non-volatile exudations that deter different soil fungal groups in the soil. We isolated the symbiotic bacteria species (Alcaligenes faecalis) from the EPN Oscheius spp. and ran infectivity bioassays against entomopathogenic fungi (EPF) as well as against plant pathogenic fungi (PPF). We found that both volatile and non-volatile symbiotic bacterial exudations had negative effects on both EPF and PPF. Such deterrent function on functionally different fungal strains suggests a common mode of action of A. faecalis bacterial exudates, which has the potential to influence the structure of soil microbial communities, and could be integrated into pest management programs for increasing crop protection against fungal pathogens.
土壤栖居性昆虫病原线虫（EPN）通过将共生细菌注入宿主血淋巴来杀死节肢动物宿主，并在宿主尸体上以几代循环的方式以细菌和死亡宿主的组织为食，直到节肢动物尸体完全耗尽。EPN-细菌-节肢动物尸体复合物是周围机会性土壤真菌生物群和其他竞争者的丰富能源。我们假设 EPN 需要保护其食物源直到耗尽，并且 EPN 共生细菌会产生挥发性和非挥发性分泌物，以阻止土壤中不同的土壤真菌群。我们从 EPN Oscheius spp. 中分离出共生细菌物种（粪产碱杆菌），并对昆虫病原真菌（EPF）以及植物病原真菌（PPF）进行了感染力生物测定。我们发现挥发性和非挥发性共生细菌分泌物对 EPF 和 PPF 都有负面影响。这种对功能不同的真菌菌株的抑制作用表明，粪产碱杆菌细菌分泌物具有共同的作用模式，有可能影响土壤微生物群落的结构，并可整合到害虫管理计划中，以增加作物对真菌病原体的保护。
