Analysis and develerent of micmenviroment in aerobic/anaerobic soils controlling microbial consortia for remediation

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Soil is a heterogenous environment composed of solid, liquid and atmospheric phases. Microorganisms introduced into soil in the procedure of bioaugumentation for degrading hazardous chemicals are considered to grow only at the microsites with favorable environments. Until now, it has been believed that the growth of soil microorganisms are affected by soil structure of microsites. However, the factors and mechanisms determining the microbial growth at the microsites are not well understood. Especially, the effects of space and physical microenvironment has not been focused. In this project, we evaluate the effect of soil microenvironment, especially physical environment, on microbial growth and the community structure.Microbial biomass and community structure were measured by respiratory quinone profile analysis, direct microscopic method, PCR-DGGE analysis of 16S RNA genes. Microbial activity was measured by dehydrogenase in the case of aerobes and by PCB dechlorination activity in the case of anaerobes.We evaluated the effects of particle size, moisture content and consolidation of soils on the growth and community structure of aerobic microorganisms. Significant effects were observed in particle size and moisture content. Microbial community structure became stable after 1 month of incubation. As model particles, four glass beads with different average diameter (0.01mm to 2mm) were used to make a homogenous physical environment. In aerobic microorganisms, with the decrease of diameter of glass beads, the degree of growth decreased and the ratio of Actinobacteria to Proteobacteria increased. In anaerobic microorganisms, although PCB dechlorination activity was not affected significantly, the different glass beads size resulted in the different community structure.