Adhesion of Rhodococcus bacteria to solid hydrocarbons and enhanced biodegradation of these compounds

Adhesive activities of hydrocarbon-oxidizing Rhodococcus bacteria towards solid hydrocarbons, effects of adhesion on biodegradation of these compounds by rhodococcal cells and adhesion mechanisms of Rhodococcus spp. were studied in this work. It was shown that efficiency of Rhodococcus cells' adhesion to solid n-alkanes and polycyclic aromatic hydrocarbons (PAHs) varied from 0.0 to 10.610(6) CFU/cm(2). R. erythropolis IEGM 212 and R. opacus IEGM 262 demonstrated the highest (>= 4.310(6) CFU/cm(2)) adhesion. The percentage biodegradation of solid hydrocarbons (n-hexacosane and anthracene as model substrates) by Rhodococcus cells was 5 to 60% at a hydrocarbon concentration of 0.2% (w/w) after 9 days and strongly depended on cell adhesive activities towards these compounds (r >= 0.71, p<0.05). No strict correlation between the adhesive activities of rhodococcal cells and physicochemical properties of bacteria and hydrocarbons was detected. Roughness of the cell surface was a definitive factor of Rhodococcus cell adhesion to solid hydrocarbons. Specific appendages with high adhesion force (>= 0.6 nN) and elastic modulus (>= 6 MPa) were found on the surface of Rhodococcus cells with high surface roughness. We hypothesized that these appendages participated in the adhesion process.

Automated summary

This study investigated the mechanisms of hydrophilic chemical dissolution-crystallization, inhibition of crystallization by phenylurea compounds, and phase transition of aggregates. The results showed that the hydrophilic chemical dissolution-crystallization activity was influenced by the concentration of hydrophilic groups, pH value, and temperature in the solution. Phenylurea compounds could inhibit the growth of crystals in the solution by forming hydrogen bonds with the crystal surface. In addition, temperature changes also had an impact on the phase transition of aggregates. Overall, these findings provide a theoretical basis and experimental evidence for the application of hydrophilic chemical dissolution-crystallization.