Degradation of acrylic copolymers by white-rot fungi

Various water-soluble homopolymers and copolymers of acrylamide (AAm) and acrylic acid (AA) which contained phenolic sites, such as guaiacol, lignin sulfonate (LS) and 3,4-dihydroxybenzoic acid (3,4-DHBA), were tested with regard to their degradability by white-rot fungi. Compared with Phanerochaete chrysosporium, Pleurotus ostreatus caused a significantly higher decrease in the average molecular weight (M-w) of most of the copolymers and the homopolymer under the applied culture conditions. However, the M-w, of poly (guaiacol/AAm) increased significantly during incubation with Pl ostreatus. P chrysosporium was able to reduce only the Mw of the poly(LS/AA) to a significant degree and not that of the other polymers. The mineralization rate of AAm and AA copolymers and terpolymers of AAm, AA and phenolics (LS, 3,4-DHBA, guiacol), which were tested with R ostreatus and Trametes versicolor, turned out to be low (0.8-3.2%). While the rates of mineralization were similar among all polymers, the decrease in radioactivity from the culture media was higher with the terpolymers bearing phenolic sites. UV spectra of the culture media revealed that the phenolic sites in the terpolymers were significantly degraded by both fungi. Obviously, the degradation of phenolics within the polymer chain caused a higher decrease in M-w but did not significantly increase the mineralization rate.