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

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.

Design and Optimization of Laccase Immobilization in Cellulose Acetate Microfiltration Membrane for Micropollutant Remediation

“…Intermolecular bonds formed by cross-linking can chemically stabilize the protein and increase the rigidity of protein structure [52], but might result in decreased activity. Therefore, the cross-linker concentration and temperature have a definitive effect on the level of cross-linking.…”

2,4-Dichlorophenol biotransformation using immobilized marine halophilic Bacillus subtilis culture and laccase enzyme: application in wastewater treatment

“…Therefore, this report may provide more information about immobilized bacterial laccase derived from marine halophilic B. subtilis AAK for efficient biotransformation of some phenolic compounds in a contaminated environment. Ammonium sulfate (85%) as a precipitant [39] and 3% alginate (356.70 U/g carrier) as an immobilization carrier were found to be the most favorable conditions for immobilizing B. subtilis AAK laccase. Due to its low cost and biodegradability, alginate was utilized as a common carrier for immobilizing many enzymes [40,41].…”

From Enzyme Stability to Enzymatic Bioelectrode Stabilization Processes

“…FTIR analysis of CLEAs highlighted changes in the secondary structure of enzymes, with an increase in β-sheet and α-helix components and a decrease in β-turns compared to free enzymes, showing the ability of CLEAs to stabilize enzymes [169][170][171]. A wide variety of enzymes, including hydrolases, oxidoreductases, lyases, and transferases have been used as CLEAs especially for organic synthesis [172,173], displaying enhanced stability under various conditions: protection against organic solvents [174], enhanced thermostability [175], reduced substrate inhibition [176,177], enhanced stability in acidic or alkaline conditions [178,179] or under storage [180]. Magnetic CLEAs combined the advantages of CLEAs and covalent immobilization onto Fe3O4 magnetic particles and may show increased stability to changes of pH and temperature [181,182].…”

“…Hence, the choice of precipitant, cross-linker, and ratio of cross-linker protein is a critical step for maintaining required flexibility of the structure for high activity [185]. These parameters strongly depend on the enzyme, making the CLEA technology delicate [174].…”