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.