Screening of Beneficial Microbial Strains

As the only edible plant of silkworm, mulberry is widely planted in the subtropical and temperate regions of the world, and is the material basis for the development of sericulture. With the proposal of mulberry industry, mulberry is widely used in animal husbandry, food, medicine and other aspects. Although the use of chemical fertilizer and pesticide in mulberry garden can improve the yield of mulberry tree, the long-term massive application also causes soil pollution and ecological environment deterioration in mulberry garden. As a new type of fertilizer, microbial fertilizer has the characteristics of improving soil, improving soil fertility, controlling pests and diseases, increasing crop disease resistance, etc. It plays an important role in promoting the reduction and efficiency of fertilizer and pesticide. The research and development of mulberry microbial fertilizer can promote the green and sustainable development of mulberry garden. Screening of safe and effective microbial strains can provide more alternative strain resources for the research and development of mulberry microbial fertilizer.In this study, the mulberry tree and the domestic silkworm were used as materials, With mulberry rhizosphere soil bacteria, mulberry endophytic bacteria and silkworm intestinal bacteria as the target bacteria, Bacterial isolation and identification of 180 mulberry rhizosphere soil samples and mulberry rhizome and leaf samples collected from six places in Guangdong province, And the isolated bacteria, And analysis of nitrogen fixation, phosphorus dissolution, potassium lysis and siderophore capacity by culture medium, Colony observation, Gram staining, scanning electron microscope (SEM) observation, biochemical test analysis, molecular biology identification, fermentation condition analysis of the screened bacteria, The fermentation metabolites were analyzed by ultra-high pressure liquid chromatography / quadrupole tandem time-of-flight mass spectrometer (liquid mass, LC-MS, Q-TOF), And by performing a composite analysis, This paper discusses the fertilizer effect of new fertilizer products on mulberry and the safety of silkworm.

桑树作为蚕的唯一食用寄主植物，在全球亚热带与温带区域广泛栽培，是蚕丝产业发展的物质基础。随着桑产业理念的提出，桑树现已广泛应用于畜牧业、食品、医药等诸多领域。尽管桑园施用化肥与农药可提升桑叶产量，但长期大量使用亦会造成桑园土壤污染与生态环境恶化。微生物肥料作为一类新型肥料，具备改良土壤、提升土壤肥力、防控病虫害、增强作物抗病性等特性，在推动化肥农药减量化与增效方面发挥着重要作用。桑树专用微生物肥料的研发，可助力桑园实现绿色可持续发展；筛选安全有效的微生物菌株，则能为桑树微生物肥料的研发提供更多可选菌种资源。本研究以桑树与家蚕为实验材料，以桑树根际土壤细菌、桑树内生细菌及家蚕肠道细菌为目标菌，对采自广东省6个采样点的180份桑树根际土壤样品、桑根茎与叶片样品进行细菌分离与鉴定；通过培养基培养、菌落形态观察、革兰氏染色、扫描电子显微镜（Scanning Electron Microscope, SEM）观察、生化试验分析、分子生物学鉴定，对筛选得到的菌株开展固氮、解磷、解钾及嗜铁素合成能力检测，并对菌株发酵条件进行优化；采用超高效液相色谱-四极杆串联飞行时间质谱仪（Ultra-High Pressure Liquid Chromatography / Quadrupole Tandem Time-of-Flight Mass Spectrometer，LC-MS Q-TOF）分析其发酵代谢产物；最终通过综合分析，探讨该新型肥料产品对桑树的肥效及对家蚕的安全性。