黑翅土白蚁栽培鸡枞菌的机制研究

China is a country with large amounts of agricultural and forestry wastes. The development and utilization of agricultural and forestry wastes to produce high quality edible fungi is not only of great significance to develop circular forestry and agriculture, but also has a profound impact on the promotion of innovation of regional agroforestry. Odontotermes formosanus is fungus-growing termite which regard trees, cutting piles , dead branches, shrubs and herbs, faeces of herbivores, etc. as food in forests of southern China, but the mechanisms of how they cultivate Termitomyces albuminosus by using plant material remains unclear. Over the past ten years, under the continuous support of the NSFC general project, we have first established the technology and methods to rear O. formosanus colony at the room condition, which clarified the mechanism of complete deconstruction of lignocellulose by the O. formosanus and its symbiotic microorganisms within three hours, and defined the division of labor of different age worker termites, and screened the material formulation to culture the spherules of T. albuminosus, and achieved the differentiation from mycelium of spherules to primordium of T. albuminosus. These results create good condition for further study. In this study, we will study the impact of different agricultural and forestry wastes and pretreatment methods on the construction of fungus combs of O. formosanus, the physiochemical and ecological mechanism of spherules of T. albuminosus to differentiate and form the mushroom on the fungus comb, and the impact factors of T. albuminosus mushroom growth on the agricultural and forestry wastes. Through these studies, we hope to resolve the key scientific problem of how spherules of T. albuminosus differentiates to form fruiting body. If that, we can provide the corresponding theoretical basis and the necessary key technology for use of biomass resources of agricultural and forestry wastes as the main material to cultivate T. albuminosus mushroom.

我国农林废弃物资源十分丰富，利用农林废弃物生产高品质食用菌对发展循环农林业和推动农林业创新具有较重要的意义。黑翅土白蚁是一种以植物为食的培菌白蚁，但其如何调配食物种类来培养鸡枞菌目前仍不清楚。过去十年里，在国家自然科学基金项目的连续资助下，本课题组在建立室内规模化饲养黑翅土白蚁巢群技术的基础上，阐明了黑翅土白蚁与共生微生物协同降解木质纤维素的机制，建立了菌圃上小白球菌继代培养的配方，实现了小白球菌菌丝体向鸡枞菌原基的分化，这些成果为本项目研究打下了良好基础。本项目将研究不同农林废弃物及预处理方式对黑翅土白蚁构建菌圃的影响、小白球菌分化形成鸡枞菌的生理生化与生态机制及利用农林废弃物培养鸡枞菌的影响因素等，以回答“黑翅土白蚁巢内菌圃上共生的小白球菌究竟是如何分化形成子实体鸡枞菌的？”这一关键科学问题，从而为利用农林废弃物等生物质资源作为主要原料栽培鸡枞菌提供相应的理论基础和必需的关键技术。

黑翅土白蚁是一种以植物为食的培菌白蚁，但其巢内菌圃上共生的小白球菌是如何分化形成鸡枞菌的一直不清楚。为了弄清这一问题，在过去的四年里，我们对不同农林废弃物及预处理方式影响黑翅土白蚁菌圃构建的方式、小白球菌分化形成鸡枞菌的生理生化与生态机制及利用农林废弃物培养鸡枞菌的影响因子等方面做了大量的室内外研究工作。结果表明，在供试的9种农林废弃物中，黑翅土白蚁最喜食榆树，不喜食泡桐和水稻秸秆；广玉兰树枝在野外堆放2个月时白蚁最喜食，且自然堆积和真菌处理会改变菌圃的理化性质；菌圃各层中，中层的细菌丰富度最高；菌圃自上往下，拟杆菌门细菌和浮霉菌门细菌渐少，厚壁菌门细菌含量基本稳定，变形菌门和放线菌门细菌增多。厚壁菌门细菌可促进鸡枞菌的生长，变形菌门的细菌对鸡枞菌生长无促进作用。在改良的马丁培养基中添加菌圃提取物，可使鸡枞菌菌丝生长更好，促进鸡枞菌菌丝生长的是可溶性糖类物质。通过配比优化，获得了鸡枞菌的培养基最佳配方。理化性质测定结果表明，生长了鸡枞菌与未生长鸡枞菌的菌圃在含水量、pH值、还原糖和纤维素、半纤维素、木质素、灰分、粗蛋白等含量方面具有较大的差异。总体上来看，未生长鸡枞菌菌圃的微生物多样性要比生长了鸡枞菌的菌圃更高。生长鸡枞菌后，菌圃中优势细菌为变形菌门、拟杆菌门和放线菌门，未生长鸡枞菌菌圃中含量最高的拟杆菌门在生长了鸡枞菌后含量减少。生长了鸡枞菌后，菌圃腔内的温度和O2含量升高，湿度和CO2浓度下降；菌圃中的Chitinophagaceae、Comamonadaceae、Rhizobiaceae等五个门的细菌含量显著增加。人工调控试验发现，菌圃上鸡枞菌子实体原基的诱导与分化与菌圃腔内的温度、湿度和CO2浓度变化有关，菌圃腔上方的土壤厚度与湿度则是促进子实体生长的重要因素。上述研究成果为利用农林废弃物等生物质资源作为主要原料栽培鸡枞菌提供了一定的理论基础和必需的关键技术。