海洋细菌（Pseudoalteromonas.SW-1）对设施农业土传病害的防治效果及作用机理研究

Greenhouse agriculture plays a pivotal role in ensuring the effective supply of agricultural products nationwide. Currently, soil function degradation, soil-borne diseases occur frequently, which seriously hampered the sustainable development of greenhouse agriculture. We screened a strain of Pseudoalteromonas spp from sediments of the China Yellow Sea, which had been proved to be of good traits, such as resistance to salt, acid and alkali, as well as tolerance of high temperature and low nutrients. Additionally, the strain could produce a variety of active substances with broad antibacterial spectrum and probiotic properties.In this project, we use the P.SW-1 as biotic-control bacteria and study its colonization mechanisms within a specific greenhouse agricultural systems under different conditions of strain concentrations, soil physical and chemical properties, crops and so on, thus optimizing its colonization conditions for the given greenhouse agriculture. Afterwards, the microbial community structures will be also studied using high throughput sequencing techniqure and gene analysis tools of molecular biology after the strain P.SW-1 colonized successfully, so as to illustrate the roles of the Pseudoalteromonas SW-1 on the species composition and diversity in the soil microecosystem of greenhouse agriculture, therefore revealing the biological inhibition mechanisms of the Pseudoalteromonas SW-1 on soil-borne pathogen. This study aims to open the treasure trove of marine microbial resources for effective prevention of soil-borne diseases, to improve soil micro-ecosystem environment, and to provide theoretical basis for soil microecology balance within greenhouse agricultual systems.

设施农业在保障全国农产品有效供给方面起到举足轻重的作用。当前土壤功能退化、土传病害频繁发生，严重制约了设施农业的可持续发展。我们已从黄海滩涂底质中筛选到1株海洋细菌--假交替单胞菌Pseudoalteromonas.SW-1(P.SW-1)，实验证实该菌具有耐盐、耐高温、耐酸碱、耐低营养等特点，产生的多种活性物质具有广谱抑菌作用及益生作用。本项目以此为研究材料，研究菌液浓度、土壤生态因子和作物种类等因素对菌株P.SW-1在设施土壤中定殖能力的影响，确认其在设施土壤中的最佳定殖条件；利用全基因的高通量测序等分子生物学分析手段，阐明施用菌株P.SW-1对设施农业土壤的微生物种群特征的影响规律；揭示菌株P.SW-1对土传病原菌的生物防治效果及其抑制机理。本项目旨在开启海洋微生物资源宝库为设施农业服务，以达到土传病害有效防治和改善设施土壤微生态环境的目的，同时为设施土壤微生态平衡提供理论依据。

土传病害是设施农业发展的限制因子之一，传统的防治模式带来一系列环境问题，海洋微生物优良特性对土传病害的防治提供可选择的途径之一。本项目筛选到3株海洋微生物可以有效地抑制设施农业土传病原菌。其中海洋假交替单胞菌P.SW-1对黄瓜枯萎病菌和草莓尖孢镰刀菌均有抑制作用，抑菌直径分别为20.33mm和14.67mm，抑菌率为26.46%和40.75%；从马铃薯炭疽病菌、黄瓜、番茄、五彩椒的病原菌土里面筛选到的植物致病菌作为指示菌进行板拮抗抑菌试验，抑制率从25.00%到65.80%，效果显著。.另外筛选到的海洋微生物菌株Y3F对黄瓜尖孢镰刀菌等设施农业病原菌的抑菌率均在70%以上，其中菌株Y3F的拮抗物质对热和酸具有稳定性，经蛋白酶K处理后基本丧失抑菌活性。随着硫酸铵饱和度的增加，菌株Y3F的抑菌活性不断增强，所以，菌株Y3F所产生的抑菌活性物质可能是蛋白类物质。其盆栽试验结果表明，能显著提高黄瓜植株生物量，对黄瓜枯萎病害的防治效果达到50.46%，同时改善根际微生物结构，其抑菌机理还需要进一步研究，具有可开发应用的前景。.海洋细菌H7同样可以抑制多种设施农业土传病原菌，在不同植物中的定殖量规律基本一致，且在番茄中的定殖量显著高于白菜、油菜以及油麦菜等十字花科植株内的定殖量，有利于该菌株在其体内发挥防病作用。海洋细菌H7在自然土中的定殖要比灭菌土中更稳定，能够促进土壤蔗糖酶活性的升高，蔗糖酶活性比对照处理高 88 mg，生防菌加入自然土中之后能与土壤中的某些土著微生物发生协作，从而有利于生防菌的存活。另外海洋细菌H7无菌上清液的抑菌活性比沉淀蛋白的抑菌活性较强，因此推断，抑菌活性物质为小分子化合物，存在于无菌上清液中，具体物质还需要进一步研究。.本项目旨在开启海洋微生物资源宝库为设施农业服务，以达到土传病害有效防治和改善设施土壤微生态环境的目的，同时为设施土壤微生态平衡和菌群互作理论提供依据。.