Partial secretome analysis of Caldariomyces fumago reveals extracellular production of the CPO co-substrate H2O2 and provides a coproduction concept for CPO and glucose oxidase

The culture supernatant of Caldariomyces fumago strains grown in a minimal medium with fructose contains mainly the biotechnologically relevant enzyme chloroperoxidase (CPO) and only minor amounts of other proteins. Our approach to identify the nature of these proteins via peptide mass fingerprinting and transcriptome analysis demonstrated the presence of putative glycosyl hydrolase and glucose oxidase (GOx) enzymes. These activities had been described earlier as parts of the fungus' halogenation machinery, as they provide CPO with the co-substrate H2O2. The GOx activity was found to have a pH optimum of 5. Compared to the wild type values, GOx activity and glucose-driven MCD chlorination activity in the culture of a white mutant were found to be strongly increased to values of 1-2 U mL(-1). As most CPO-catalyzed peroxidation reactions also show pH optima at around 5, the C. fumago culture supernatant can provide a highly convenient CPO/GOx source for many reactions with in situ H2O2 production.