EFFECT OF MANGANESE ON LIGNIN DEGRADATION BY PLEUROTUS-OSTREATUS DURING SOLID-STATE FERMENTATION

Lignin degradation by Pleurotus ostreatus was studied under solid-state fermentation (SSF) in chemically defined medium containing various levels of Mn. Degradation of [C-14]lignin prepared from cotton branches to soluble products, as well as its mineralization to (CO2)-C-14, was enhanced by the addition of Mn. The effect of malonate on lignin mineralization was most marked during the first 10 days of SSF, in a treatment amended with 73 muM Mn. A high concentration of Mn (4.5 mM) caused inhibition of both fungal growth and mineralization rates during the first 2 weeks of incubation. Addition of malonate reversed this effect because of chelation of Mn. Mn was found to precipitate in all treatments, with or without the addition of malonate. Alpha-Keto-gamma-methiolbutyric acid cleavage to ethylene, an indication of OH production, was observed as early as 3 days of incubation in all treatments.