Abstract
Response surface methodology (central composite design of experiments) was employed to simultaneously optimize enzyme production and productivities of two ligninolytic enzymes produced by Ceriporiopsis subvermispora. Concentrations of glucose, ammonium tartrate and Polysorbate 80 were varied to establish the optimal composition of liquid media (OLM), where the highest experimentally obtained activities and productivities were 41 U L−1 and 16 U L−1 day−1 for laccase (Lac), and 193 U L−1 and 80 U L−1 day−1 for manganese peroxidase (MnP). Considering culture growth in OLM on various types of immobilization support, the best results were obtained with 1 cm beech wood cubes (BWCM). Enzyme activities in culture filtrate were 152 U L−1 for Lac and 58 U L−1 for MnP, since the chemical composition of this immobilization material induced higher Lac activity. Lower enzyme activities were obtained with polyurethane foam. Culture filtrates of OLM and BWCM were applied for dye decolorization. Remazol Brilliant Blue R (RBBR) was decolorized faster and more efficiently than Copper(II)phthalocyanine (CuP) with BWCM (80% and 60%), since Lac played a crucial role. Decolorization of CuP was initially faster than that of RBBR, due to higher MnP activities in OLM. The extent of decolorization after 14 h was 60% for both dyes.
Highlights
Fungi are the main organisms responsible for wood biodegradation
In order to optimize the model consisting of two factors that needed to be improved simultaneously as a single system response, the Objective Functions (OFLac and OFMnP) for batch experiments were expressed by: OFLac
1,Mnp w y 2,Mnp 1 w max where ([ELac])max and ([EMnP])max are the highest values of the experimentally obtained maximal Lac and manganese peroxidase (MnP) activities ([ELac] and [EMnP] in U L−1) for all settings presented in Table 1, w is the weighting factor, (d[ELac]/dt)max and (d[EMnP]/dt)max are the highest values of experimentally obtained maximal Lac and
Summary
Fungi are the main organisms responsible for wood biodegradation. Some species of basidiomycetes, the white-rot fungi, are able to efficiently degrade lignin [1]. In order to do that, they produce extracellular oxidative enzymes such as laccase (Lac), lignin peroxidise (LiP) and manganese peroxidise (MnP) [2,3]. Their non-specific oxidative mechanism makes them useful for a wide range of biotechnological applications in the pulp and paper industry and in bioremediation technologies for degradation of recalcitrant compounds [4]. The basidiomycete C. subvermispora is a well-known fungus in the bio-pulping and paper industry because it is a selective lignin degrader [5,6]. The decomposition of lignin from various resources may be achieved in an optimal manner and the resulting medium can effectively be utilized as a substrate in bioethanol or biogas producing fermentations following less demanding upstream processing
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