Nonlinear changes in the activity of the oxygen-dependent demethylase system in Rhodococcus erythropolis cells in the presence of low and very low doses of formaldehyde.

The effect of exogenous, highly diluted formaldehyde on the rate of demethylation/re-methylation of veratric acid by the bacteria Rhodococcus erythropolis was studied using electrophoretic and microscopic techniques. The activity of 4-O-demethylase, responsible for accumulation of vanillic acid, and the levels of veratric and vanillic acids were determined using capillary electrophoresis. Formaldehyde was serially diluted at 1:100 ratios, and the total number of iterations was 20.

Influence of very low doses of mediators on fungal laccase activity - nonlinearity beyond imagination.

Laccase, an enzyme responsible for aerobic transformations of natural phenolics, in industrial applications requires the presence of low-molecular substances known as mediators, which accelerate oxidation processes. However, the use of mediators is limited by their toxicity and the high costs of exploitation. The activation of extracellular laccase in growing fungal culture with highly diluted mediators, ABTS and HBT is described.

Effect of low and very low doses of simple phenolics on plant peroxidase activity.

Changes in the activity of horseradish peroxidase resulting from an addition of ethanol water dilutions of 19 phenolic compounds were observed. For each compound, the enzyme activity was plotted against the degree of dilution expressed as n = -log(100) (mol/L) in the range 0 /= 20. All the curves showed sinusoidal activity, more or less regular, with two to four peaks on average.

Relationship of demethylation processes to veratric acid concentration and cell density in cultures of Rhodococcus erythropolis.

The aim of this study was to investigate the correlation between veratrate degradation, veratric acid concentration and cell density in Rhodococcus erythropolis cultures. The optimum culture conditions for veratrate demethylation proved to be a cell density of A(660)=1 and a concentration of 0.02% veratrate.

Effect of low doses of guaiacol and ethanol on enzymatic activity of fungal cultures.

The influence of low doses of guaiacol and ethanol, the natural effectors of lignin and phenolics transformations, on laccase and peroxidase activities produced by two strains of Basidiomycetes, Pleurotus sajor-caju and Trametes versicolor, was evaluated. Fungal mycelia were grown for 2 weeks on liquid media containing serial dilutions of guaiacol or ethanol ranging from 100(-1) to 100(-20) mol/L. Laccase and peroxidase activities in the medium were measured at the end of 2 weeks.