Search

Researchers demonstrate for the first time the biodegradation of lignin in solid pine wood by manganese peroxidase from the white-rot fungus Phlebia radiata. In this system, a nonphenolic lignin structure that is not normally degraded by manganese peroxidase was oxidizable.

Manganese peroxidase (MnP) is the predominant ligninolytic enzyme during solid-state fermentation (SSF) of wheat straw with the white rot fungus Nematoloma frowardii. The fungus generates sufficient amounts of organic acids for effective MnP activity. Aside from MnP, low levels of laccase and lignin peroxidase were also detected during SSF. Synthetic 14C-ring labeled lignin was degraded during SSF. About 75% of the initial radioactivity was released as (super 14)CO(sub 2), while only 6% was associated with the residual straw material, thus leading to the conclusion that at least partial extracellular mineralization of lignin may have taken place.

The fungus Phlebia (P.) radiata 79 may produce large amounts of the enzymes lignin peroxidase (LiP), manganese peroxidase (MnP), laccase, and glyoxal oxidase (GLOX) while breaking down wheat straw. Researchers extracted enzymes produced by the fungus during solid-state fermentation of wheat straw. In comparison to liquid fementation, solid-state cultures produced new forms of MnP and GLOX and higher concentrations of the form of LiP known as LiP2.

Ligninolytic enzymes were obtained from three strains of the white rot fungus Phlebia tremellosa, and all strains exhibited a similar mineralization rate of 14C-ring-labelled synthetic lignin under a low manganese peroxidase isoenzyme Mn(II) level, to rates obtained from Phanerochaete chrysosporium and Phlebia radiata. The evolution of 14CO2 is repressed at high manganese concentrations, even in the addition of a chelating agent such as sodium malonate to the medium.

Research demonstrates that Stropharia coronilla metabolizes and mineralizes benzo[a]pyrene and manganese(II) ions significantly stimulate this process by four to twelve times, respectively. Data indicate that the stimulatory effects is mediated by the ligninolytic enzyme manganese peroxidase, whose activity increases upon manganese addition.

Results demonstrate that Collybia dryophilla K209, which colonize forest litter and soil, decomposes a natural and a synthetic humic acid with the degradation leading to the formation of polar, fulvic acid and carbon dioxide. Data indicate that manganese subsantially enhances humic acid decomposition, presumably mediated by manganese peroxidase.