Induction of Ligninolytic Enzyme Production by Dichomitus squalens on Various Types of Immobilization Support

Aleksander Pavko¹* and Čenĕk Novotný²

¹ Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia
² Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
* Corresponding author: E-mail: saso.pavko@fkkt.uni-lj.si

Abstract
The aim was to produce a mixture of ligninolytic enzymes for decolourisation of synthetic dyes typically present in textile industry wastewaters. White rot fungus Dichomitus squalens, capable of producing laccase (Lac) and manganese peroxidase (MnP) was used. A procedure for the enzyme production in stationary cultures was developed and optimized regarding the type of carbon source and addition of nitrogen to N-limited medium. Beech wood, pine wood and straw were used as inducers and immobilization support materials. Beech wood and straw were the best inducers and immobilization supports, while fructose stimulated the enzyme activities better than other sugars. An additional nitrogen source was beneficial to increase the enzyme activities in the culture medium. Higher Lac than MnP activities were determined in all cases. The obtained enzyme mixtures from the culture filtrate were tested to decolourize three structurally different dyes. The highest initial decolourisation rate was obtained with Remazol Brilliant Blue R. The decolourization efficiencies after 10 h were 62% for RBBR, 50% for Copper(II)phthalocyanine and 19% for Reactive Orange 16.

Keywords: Laccase, manganese peroxidase, Dichomitus squalens, enzyme production, mycelium immobilization, decolourisation, synthetic dyes