Phenoloxidase-producing halotolerant fungi from olive brine wastewater

The main aim of this study was to assess the ability of producing extracellular phenoloxidases (EPO) of fungi isolated from olive brine wastewater (OBW), the effluent from the debittering process of table olives. Five out of twenty isolates displayed EPO-producing ability as assessed by selective agar plate assays and were all halotolerant. Among them, Citeromyces matritensis (syn. Candida globosa) and Aspergillus fumigatus concomitantly produced laccase and Mn-peroxidase (MnP) activities. Candida boidinii and Candida bombi, instead, only produced laccase and Candida diddensiae only released MnP. Both C. matritensis and A. fumigatus, grown in shaken cultures on OBW, maintained their EPO-producing ability and removed phenols by 52.3 and 82.3%, respectively, after 10 d incubation in the non-supplemented effluent. These results might suggest the possible use of these strains in the treatment of other saline phenol-rich effluents, such as pickling and tannery wastewater.