Adhesion of bacterial cells on carbon supports: characteristics of process and application in biotechnology

The article provides a brief review of methods for studying the process of adhesion of bacterial cells on insoluble abiotic carriers (carbon materials). Determination of the hydrophobicity of microbial cells and the carrier, dispersion, surface roughness of the carrier allows to identify the main patterns of bacterial adhesion on carbon adsorbents. It is shown that the adhered biomass on a hydrophobic carrier is the greater, the higher the hydrophobicity of the cell surface. Correlation analysis showed no reliable relationship between surface roughness, hydrophobicity and dispersion of carriers on the one hand, and the mass of adhered cells on the other hand when considering these characteristics separately, which indicates the need for a comprehensive approach to the assessment of the carrier for immobilizing microbial cells. The mass (amount) of adsorbed cells depends on their concentration in the suspension. The nature of adsorption, subsequently replaced by adhesion, can be described either by the theory of polymolecular adsorption of Brunauer, Emmett, Teller, which implies the formation of a cells polylayer on the surface, or in the case of carrier saturation with cells, the graphs look like Langmuir isotherms. The elemental composition of the carrier has a certain effect on the physiological state of the adhered cells, therefore, it must be taken into account when choosing the optimal carrier of cells in heterogeneous biocatalysis. Scanning electron microscopy allows visualization of adherent cells. Adherent cells of nitrile-hydrolyzing bacteria can be used as biocatalysts for the process of enzymatic transformation of nitriles and amides or in the process of treatment of environment from these toxic substances.