Biotransformation and ecotoxicity evaluation of alkali lignin in optimized cultures of microscopic fungi

The aim of this study was to identify optimized parameters (C and N source, pH and temperature incubation) for decolorization of industrial alkali lignin by the microscopic fungi Haematonectria haematococca BwIII43, K37 and 33 Trichoderma harzianum BsIII33. To enhance the decolorization of alkali lignin, the medium was supplemented with carbon (fructose, glucose, galactose, maltose and xylose) and nitrogen sources (ammonium sulfate, ammonium nitrate, ammonium tartrate, sodium nitrate, asparagine, urea and caseine hydrolyzate). Measurements of phenolic compounds, phytotoxicology (Lepidium sativum) and ecotoxicology assay (Microtox) were performed to determine the extent of detoxification of 0.2% alkali lignin after treatment with microscopic fungi. More than 90% of alkali lignin was removed in optimized cultures of microscopic fungi Haematonectria haematococca BwIII43, K37 and Trichoderma harzianum BsIII33 (0.25% glucose, 0.25% ammonium sulfate, initial pH = 6.0, 28 °C). The phenolic compounds, phytotoxicity and ecotoxicity decreased.