The indicative culture parameters of manganese peroxidase production by white rot fungus IZU-154

Abstract

The production of manganese peroxidase (MnP) by the hyper-ligninolytic fungus IZU-154 was performed by batch and filter-cultivation using a conventional stirred fermentor. A maximum MnP activity of 9.7 nkat/ml (nano katal/ml) was obtained after 44 h in the batch cultivation, and that of 8.1 nkat/ml was observed after 20 h in the filter-cultivation. Culture parameters, such as redox potential and pH, were investigated in the batch cultivation. We also investigated a novel parameter, the nonenzymatic 2,6-dimethoxyphenol oxidation (NEOX) level, which seems to reflect the amount of Mn(III) oxidized from Mn(II) by MnP. The swift rise of the redox potential, the synchronous gradual rise of pH, and the saturation of the NEOX level were significantly correlated to the MnP production. The production of MnP and the onset of the profiles of parameters were apparently in response to Mn(II) addition to the culture fluid. Furthermore, we investigated the content of organic acids during the MnP production in the filter-cultivation. Tartrate contained in the culture medium was consumed coincidentally at the onset of MnP production, and oxalate and formate were newly produced in the culture fluid at the same time.