Penicillium chrysogenum glucose oxidase – a study on its antifungal effects

Aims: Purification and characterization of the high molecular mass Candida albicans‐killing protein secreted by Penicillium chrysogenum. Methods and Results: The protein was purified by a combination of ultrafiltration, chromatofocusing and gel filtration. Enzymological characteristics [relative molecular mass (Mr) = 155 000, subunit structure α2 with Mr,α = 76 000, isoelectric point (pI) = 5·4] were determined using SDS‐PAGE and 2D‐electrophoresis. N‐terminal amino acid sequencing and homology search demonstrated that the antifungal protein was the glucose oxidase (GOX) of the fungus. The enzyme was cytotoxic for a series of bacteria, yeasts and filamentous fungi. Vitamin C (1·0 mg ml−1) prevented oxidative cell injuries triggered by 0·004 U GOX in Emericella nidulans cultures but bovine liver catalase was ineffective even at a GOX : catalase activity ratio of 0·004 : 200 U. A secondary inhibition of growth in E. nidulans cultures by the oxygen‐depleting GOX–catalase system was likely to replace the primary inhibition exerted by H2O2. Conclusions: Penicillium chrysogenum GOX possesses similar enzymological features to those described earlier for other Penicillium GOXs. Its cytotoxicity was dependent on the inherent antioxidant potential of the test micro‐organisms. Significance and Impact of the Study: Penicillium chrysogenum GOX may find future applications in glucose biosensor production, the disinfection of medical implants or in the food industry as an antimicrobial and/or preservative agent.