Characterization of Soil Microorganism from Humus and Indigenous Microorganism Amendments

This study was conducted to understand the dynamics of microbial communities of soil microorganisms, and their distribution and abundance in the indigenous microorganisms (IMOs) manipulated from humus collected from the forest near the crop field. The soil microorganisms originated from humus and artificially cultured microbial-based soil amendments were characterized by molecular and biochemical analyses. The bacterial population (2 × 10⁶∼13 × 10⁶ CFU/g sample) was approximately 100-fold abundant than the fungal population (2 × 10⁴∼8 × 10⁴ CFU/g sample). The 16S rDNA and ITS sequence analyses showed that the bacterial and fungal communities in humus and IMOs were mainly composed of <i>Bacillus</i> and <i>Pseudomonas</i>, and <i>Trichoderma</i> and <i>Aspergillus</i> species, respectively. Some of the bacterial isolates from the humus and IMOs showed strong inhibitory activity against soil-borne pathogenic fungi <i>Fusarium oxysporum</i> and <i>Sclerotinia sclerotiorum</i>. These bacteria also showed the siderophore production activity as well as phosphate solubilizing activity, which are requisite traits for biological control of plant pathogenic fungi. These results suggest that humus and IMOs could be a useful resource for sustainable agriculture.

本研究旨在探究土壤微生物群落的动态变化，以及从农田附近森林腐殖质中获取并调控得到的土著微生物（Indigenous Microorganisms, IMOs）内，此类土壤微生物的分布与丰度特征。本研究以源自该腐殖质的土壤微生物为材料，通过分子与生化分析方法，对人工培养的微生物基土壤改良剂进行了系统表征。细菌种群丰度达(2×10⁶~13×10⁶) CFU/g样品，约为真菌种群(2×10⁴~8×10⁴) CFU/g样品的100倍。16S rDNA与ITS序列分析结果显示，腐殖质及IMOs中的细菌群落与真菌群落主要分别由芽孢杆菌属（Bacillus）、假单胞菌属（Pseudomonas），以及木霉菌属（Trichoderma）、曲霉属（Aspergillus）的物种构成。从腐殖质及IMOs中分离得到的部分细菌菌株，对土传病原真菌尖孢镰刀菌（Fusarium oxysporum）与核盘菌（Sclerotinia sclerotiorum）具有较强的抑菌活性。此类细菌同时具备嗜铁素合成活性与磷酸盐溶解活性，上述两类活性均为植物病原真菌生物防治所必需的核心功能性状。本研究结果表明，腐殖质及IMOs可作为可持续农业的潜在优质资源。