Relation of chemical properties of soil humic acids to decolorization by white rot fungus–<i>Coriolus consors</i>

Abstract

Abstract Humic acids (HAs) from 15 different soil samples were added to Czapek-Dox media inoculated with Coriolus consors IFO 9078. After 14 d incubation, decolorization of these culture media at 600 nm absorbance was measured. The aromaticity, the E 1% 600 value, the total acidity, and the elemental composition of the HAs were also determined, and the relationships between the decolorization and the chemical properties of HAs were examined. Percentage of decolorization of these culture media ranged from 8.8 to 39.5%. Andisol HAs showed a lower percentage of decolorization than the Inceptisol HAs. Percentage of decolorization showed highly negative correlations for the aromaticity, the E 1% 600 value, and the O / H ratio, and highly positive correlations for the hydrogen content and the H / C ratio. In particular, the highest correlation coefficient (r = −0.836**) was obtained between the aromati city and the decolorization. In addition, the HAs with a lower decolorization were arranged in the direction of dehydration on the H / C versus O / C diagram. These results showed that HAs with a higher aromaticity and a higher humification degree, showed a higher resistance to microbial decolorization by C. consors.