Crosslinked Enzyme Aggregates (CLEAs) of Laccases from Pleurotus citrinopileatus Induced in Olive Oil Mill Wastewater (OOMW).

Christina Pentari,Anastasia Zerva,Evangelos Topakas

doi:10.3390/molecules25092221

Abstract

The enzymatic factory of ligninolytic fungi has proven to be a powerful tool in applications regarding the degradation of various types of pollutants. The degradative potential of fungi is mainly due to the production of different types of oxidases, of which laccases is one of the most prominent enzymatic activities. In the present work, crude laccases from the supernatant of Pleurotus citrinopileatus cultures grown in olive oil mill wastewater (OOMW) were immobilized in crosslinked enzyme aggregates (CLEAs), aiming at the development of biocatalysts suitable for the enzymatic treatment of OOMW. The preparation of laccase CLEAs was optimized, resulting in a maximum of 72% residual activity. The resulting CLEAs were shown to be more stable in the presence of solvents and at elevated temperatures compared to the soluble laccase preparation. The removal of the phenolic component of OOMW catalyzed by laccase-CLEAs exceeded 35%, while they were found to retain their activity for at least three cycles of repetitive use. The described CLEAs can be applied for the pretreatment of OOMW, prior to its use for valorization processes, and thus, facilitate its complete biodegradation towards a consolidated process in the context of circular economy.

Highlights

Fungal species belonging to phylum Basidiomycota are often used for bioremediation/biodetoxification applications, due to their induced intricate enzymatic factory for the degradation of lignocellulosic biomass
The first experiment towards the preparation of crude laccase crosslinked enzyme aggregates (CLEAs) was the determination of the optimum protein loading in order to obtain satisfactory yields in terms of immobilization and avoid leaching and, loss of the enzyme
The removal of phenols reached 16.8% ± 0.5%, while, after the second cycle, an additional 0.95% ± 0.02% was removed. These results indicate that laccase-CLEAs possibly have a narrower substrate range in regard to olive oil mill wastewater (OOMW)

Summary

Introduction

Biodetoxification applications, due to their induced intricate enzymatic factory for the degradation of lignocellulosic biomass Their potential for the biodegradation of organic pollutants lies in several major oxidative enzyme activities, mainly laccases (benzenediol:oxygen oxidoreductases, Lac, EC 1.10.3.2) and peroxidases, including manganese peroxidases (MnP, EC 1.11.1.13), lignin peroxidases (LiP, EC 1.11.1.14), and versatile peroxidases (VP, EC 1.11.1.16), among others [1]. These enzymes have been employed in the degradation of a wide range of pollutants, such as endocrine disrupting chemicals [2], dyes [3], pesticides [4], substituted phenols, pharmaceuticals [5], and others. Many basidiomycetes are able to degrade OOMW almost completely [1,7,8,9], but the need for sterilization and the long

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Results

Conclusion