Effect of addition of extracellular culture fluid on ligninolytic enzyme formation in Phanerochaete chrysosporium

Abstract

The influence of extracellular ligninolytic fluid addition on lignin peroxidase (LIP), Mn-peroxidase (MNP) and glyoxal oxidase (GLOX) activity in free and immobilized (polyurethane foam) batch cultures of Phanerochaete chrysosporium was examined. Addition was carried out in several proportions during growth (day 0) and idiophasic phase (day 4). A decrease in the activity of added LIP was observed for both free pellets and immobilized cultures. In both cases, a de novo LIP activity was slightly lower than in control cultures (without addition). MNP and GLOX activity was not significantly altered by the addition of ligninolytic extracellular fluid. LIP and MNP isoenzymes were detected in different degrees, showing a typical behaviour of N-limited cultures of P. chrysosporium monitored at 409 nm. During late secondary metabolism in immobilized cultures, a second peak of ligninolytic activity was obtained, for which the level of LIP activity was similar to the first one, but glyoxal oxidase activity was 3-fold higher. Isoenzyme profile for this second peak was typical of C-limitation, being H2 isoenzyme the predominant hemeprotein for all assays. Total protein profile (monitored at 280 nm) also showed another peak at 1.5-min elution volume, whose area was quite similar to the one obtained for H2. The proteins eluted at 1.5 min were isolated and analyzed by SDS-electrophoresis, detecting a band displaying proteolytic activity.