BIODEGRADATION OF PHENOL, CATECHOL AND 2, 4-DICHLOROPHENOL AT HIGHER INITIAL INHIBITORY CONCENTRATIONS BY TRAMETES VERSICOLOR 1 IN A “FED-BATCH” PROCESS

Abstract

Biodegradation of phenol, catechol and 2,4-dichlorophenol, at higher initial inhibitory concentrations, by Trametes versicolor 1 in a “fed-batch” process is investigated. The strain (2.5 g biomass) biodegrades total 7.45 g phenol for 20 days at initial phenol concentration of 1.0 g/dm³ and 6 feedings with concentration 1 g/dm³. At initial concentration of catechol and 2,4-dichlorophenol 2.0 g/dm³ and feedings with same concentration, the culture (2.5 g biomass) biodegrades respectively total 11.13 g catechol for 22 days at 5 feedings and 3.03 g 2,4-dichlorophenol  at 1 feeding for 6 days. It is established that Trametes versicolor 1 synthesizes phenol-hydroxylase, catechol 1,2-oxygenase and laccase – enzymes, required for biodegradation and biotransformation of the above phenolic substrates. Laccase production depends on the nature of the substrate. Strain produces considerable amount of laccase reaching to 1343.3 U/cm³ in medium containing catechol but the enzyme is not being synthesized in the medium comprised of 2,4-dichlorophenol as sole carbon and energy source.  The enzyme activities of phenol hydroxylase и catechol 1,2- oxygenase are higher in media with catechol than in media with other two phenolic compounds. At the end of the biodegradation process of the phenolic compounds, the second enzyme of the catabolic pathway – catechol 1,2-oxygenase is not identified in the medium. The absence of the second enzyme of the metabolic pathway is probably the decisive factor for the termination of the biodegradation process.