Utilization of Substrates and Transformation of Solid Substrata

Abstract

Solid adsorbents which play a role in microbial adhesion influence the growth and metabolic activity of microorganisms and utilization of substrates. Usually, different adsorbents enhance the specific growth rate and molar growth yield in pure and mixed cultures of bacteria, actinomycetes, and fungi. In the dependence of the microorganisms tested, of adsorbents used, and of cultivation conditions maintained, stronger glycolytic or oxidative utilization of a carbon source can be observed. Formation of humic substances is generally increased. The mechanism of the effect of adsorbents on microbial utilization of substrates is very complex and includes the adsorption of cells, substrates, enzymes and other microbial metabolites, as well as degradation products. Electron transfer from cell to solid surface and the hydrophobicity of the solid surface may be involved. Different biotic and abiotic materials serve as solid substrata in microbial adhesion, and they can be transformed by microorganisms. Both superficial and substantial transformation may occur in which exoenzymes and other metabolic products are involved. Further analytical studies are necessary to elucidate the relationship between microorganisms and surfaces and how they influence microbial growth, utilization of different substrates, and transformation of solid substrata.