C-13 NMR SPECTROSCOPIC ANALYSIS OF SOIL HUMIC ACIDS RECOVERED AFTER INCUBATION WITH SOME WHITE ROT FUNGI AND ACTINOMYCETES

Culture media containing soil humic acids were inoculated with either white-rot fungi (Phanerochaete chrysosporium and Trametes versicolor) or actinomycetes (Streptomyces viridosporus and Streptomyces sp.) and incubated until a loss of about 30% of humic acids had occurred in the growth medium. The humic acids were recovered by the use of a metal chelate affinity procedure and studied by C-13 NMR spectroscopy in order to collect more information about the mechanism of attack on humic acids. The spectra resulting from fungal activity were the most modified; however, no important changes in the main constituents of these compounds and no increase in carboxyl content were recorded. The results suggest an unusual degradation process.