Screening of microscopic fungi and their enzyme activities for decolorization and biotransformation of some aromatic compounds

A total of 610 strains from 16 species of micromycetes with potential ligninolytic capabilities were isolated from soil, compost, and rotten wood, including 400 strains of soil origin. In the test of decolorization of agarized 0.06 % alizarin blue, 52 strains with high decolorization activity were selected. In liquid cultures with 0.2 % post-industrial lignin and 0.03 % alizarin blue, all of the selected strains showed three different extracellular peroxidase activities such as HRP-like, LiP, and MnP. Laccase was detected only in the cultures with alizarin blue, but those were trace amounts. In the decolorization of alizarin blue, the highest levels of activity were attained by HRP-like peroxidase. In the transformations of post-industrial lignin that included decolorization, colorization (darkening of substrate), and re-colorization, the highest levels of activity were attained by lignin peroxidase, especially at the start of the culture. The transformations of both dye substrates in the cultures of all 52 strains were accompanied by the release of glucose oxidase, but high activities of that enzyme were observed only in the presence of alizarin blue. Whereas in the presence of lignin the fungi under study synthesized catalase, the activity of which attained a maximum toward the end of the culture was negatively correlated with the activity of the remaining oxidoreductases under study. Among the 52 selected strains, three strains such as Haematonectria haematacocca BwIII43, K37, and Trichoderma harzianum BsIII33 were characterized by a high activity of decolorization.