Laccase–cellobiose dehydrogenase-catalyzed detoxification of phenolic-rich olive processing residues

Abstract

The combination of a laccase-hydroxybenzotriazole (HBT) mediator system with/without cellobiose dehydrogenase (CDH) or an additional Fenton reaction step for the elimination and/or detoxification of phenolic compounds in dry olive mill residues (DOR) and liquid olive mill wastewaters (OMW) was evaluated. The laccase-HBT-CDH and laccase-HBT-CDH-Fenton system were the most effective, removing at least 69 and 72 % of phenolic compounds from a total of 698 and 683 mg in OMW and DOR, respectively, in 12 h. The efficient removal of phenolic compounds was also accompanied by [80 % reduction in biochemical oxygen demand and chemical oxygen demand in both DOR and OMW. Microbial community analysis using single-strand conformation polymorphism (SSCP) gels showed that biogas reactors supplemented with untreated and laccase-HBT-CDH-Fenton-treated DOR and OMW strongly inhibited growth of microorganisms. In contrast, the laccase-HBTand laccase-HBT-CDH-pretreated OMW and DOR were detoxified as evidenced by SSCP analysis, which also indicated a distinct sensitivity of the individual members of the anaerobic population toward the toxicants. Further, although the laccase-HBT-CDH-Fenton system was effective in bleaching and removing phenolic compounds in both OMW and DOR, it was not able to support methane production. However, laccase-HBT and laccase-HBT-CDH indeed supported biogas production. This study therefore shows that the laccase-HBT-CDH system has a potential for the detoxification of olive mill residues, which can be potentially used as substrates for downstream processes.

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

“…Justino et al [ 41 ] showed varying degrees of phenol removal from OOMW (4–70%) with a commercial laccase from T. versicolor after treatment for seven days with a starting phenol concentration of 60.8 mg L −1 , much lower than in the present study. Nugroho Prasetyo et al [ 42 ] tested various laccases from different sources, supplemented with 1-hydroxybenzotriazole as the mediator, for the phenol removal of OOMW, with a starting concentration of 689 mg L −1 . The application of laccase from Trametes villosa resulted in 64% phenol removal, while Myceliophthora thermophila laccase removed up to 32% in 24-h experiments.…”

Potential of industrial by-products and wastes from the Iberian Peninsula as carbon sources for sulphate-reducing bacteria

“…Moreover, polyphenols are also important in OMW (0.0002 to 1.5%). It has been discovered that one of its most abundant phenolic compounds (1,4-tyrosol) can be oxidized by a SRB (Desulfovibrio marrakechensis) isolated for the first time from OMW in Morocco (Chamkh et al 2009) and identified by 16S rRNA gene sequence analysis in OMW from Greece after treatment tests using amendments of laccase and cellobiose dehydrogenase (Prasetyo et al 2015). This raises the hypothesis that SRB with this metabolic pathway may exist as well in OMW ponds in Portugal.…”