Evaluation of different carbon sources for production of iron-reducing compounds by Wolfiporia cocos and Perenniporia medulla-panis

Wood decaying fungi grown in different culture media were evaluated for production of low molecular weight compounds (catecholate and hydroxamate derived and glycopeptides) with Fe3+-reducing activity. The brown-rot Wolfiporia cocos and the white-rot Perenniporia medulla-panis were selected because they had previously been reported to produce Fe3+-reducing compounds. Cultures were grown in liquid media with different carbon sources: glucose, l-ornithine, and succinic acid, all with and without microcrystalline cellulose supplementation. The fungi displayed different growth in different culture media and visually, the presence of cellulose promoted the highest biomass production. Catecholate compounds were produced mostly when glucose-cellulose was the carbon source for W. cocos and ornithine-cellulose for P. medulla-panis. Production of hydroxamate compounds were stimulated in ornithine-cellulose medium for W. cocos and in ornithine for P. medulla-panis. Moreover, no production of low molecular weight (<5 kDa) glycopeptides was detected using the Bradford protein assay. The highest Fe3+-reducing activities produced by W. cocos and P. medulla-panis were obtained in the same culture medium in which the highest catecholate compounds production was detected. Microcrystalline cellulose supplementation seemed to increase catecholate compounds production with concurrent increase of Fe3+-reducing activity by both fungi.