A study on microbial flora and environmental factors related to selerotium grain formation

菌核是外生真菌的休息体，在森林土壤中形成黑色球形结构，由厚厚的黑色素壁保护。通过对菌核形成相关微生物区系和环境因子的研究，阐明了菌核发育在土壤生态系统中的共生作用。用X射线光电子能谱分析了菌核中主要元素C、Al、O的含量和化学结合状态。在对谷粒内微生物区系的实验中，预期的嗜地梭菌的分离尚未成功，除与粘红酵母相关的菌株外，大多数菌株都是未知的种。细菌群落分析显示，甲型变形杆菌占优势，主要是鞘氨醇单胞菌。我们分离的鞘氨醇单胞菌不太可能对铝毒有显著的耐受性。本文研究了德国哈尔茨山Podsole、Braunfahlerde和Braunerde-Podsoles森林土壤以及山区火山灰土壤中真菌菌核分布与土壤化学性质的关系。Myoko和Mt.秋田-小松，日本中部。哈尔茨山不同森林土壤中菌核颗粒的形成。受到活性铝的状态和有毒铝(Al3)含量的强烈调控，这一点在日本安多索中得到了证实。阐明了铝的存在与硒的发育之间的关系，而与土壤类型和土壤酸度无关。

Sclerotium grains, the resting bodies of ectomycorhizal fungi, are formed in forest soils as black spherical structures protected by thick and melanin-pigmented walls. Microbial flora and environmental factors related to the formation of sclerotium grains were studied to elucidate the symbiotic function of selerotium grain development in soil ecosystem. The content and chemical binding states of the major elements, C, Al, and O, in sclerotium gains were examined by X-ray photoelectron spectroscopy analysis. As for the experiments on the microbial flora inside the grains, the expected isolation of C. geophilum was not yet successful and most of the isolates were unknown species except strains relative to Rhodotorula mucilaginosa spp. Bacterial community analysis revealed the predominance of Alphaproteobacteria, chiefly the Sphingomonas group. It was unlikely that our Sphingomonas isolates had remarkable tolerance to aluminum toxicity. The relationships between the distribution of fungal sclerotium grains and soil chemical properties were studied in forest soils of Podsole, Braunfahlerde and Braunerde-Podsoles in Harz Mts., Germany and in volcanic ash soils of Mt. Myoko, and Mt. Akita-Komagatake, Central Japan. The formation of sclerotium grains in various forest soils of the Harz Mts. was strongly regulated by the state of active aluminum and the content of toxic Al (Al3+) as confirmed in Japanese Andosols. The relationship between the existence of aluminum and selerotium development was elucidated regardless of the soil type and the strength of soil acidity.