Physiological Aspects of Biosynthesis of Lignin Peroxidases by Phanerochaete chrysosporium

Abstract

Methods based on UV-visible diffuse reflectance spectroscopy were used to study the physiological aspects of lignin-peroxidase biosynthesis by Phanerochaete chrysosporium. Here we introduce the use of cytochrome aa3 as an indicator of active fungal biomass and of its redox state to calculate the oxygen mass transport coefficient between the growth medium and the fungal cell interior. When lignin peroxidase biosynthesis was enhanced by the addition of Tween 80 or Tween 20 to the growth medium, a higher proportion of reduced cytochrome aa3 and a higher oxygen diffusion barrier were observed compared with control cultures. In cultures supplemented with Tween 80 or Tween 20, a higher oxygen mass transport coefficient between the growth medium and the interior of the fungal cell was also found. The beginning of the lignin peroxidase activity in these cultures was found to coincide with a temporary cessation in the dry biomass increase and a reduction in the relative active-biomass concentration. During the lignin peroxidase activity, a decrease in the intracellular pH and an increase in the growth medium pH were determined in cultures supplemented with Tween 80.

Ligninolytic Enzymes of the White Rot Basidiomycete Trametes trogii

“…The increased laccase levels could be attributed in part to the stimulatory effect of Tween 80 on biomass production. However, other factors such as increased cell membrane permeability and/or promotion of the release of cell bound enzymes, might play a role [21]. These two possibilities are in agreement with the fact that Tween 80 cultures were 70% higher in extracellular proteins than the control.…”

Production of Fungal Laccase Using Orange Peelings as Substrate by Submerged Static Fermentation

“…Patel and Gupte [36] also reported the increase in yield of laccase after the addition of Tween 80. Similar results have been reported in other studies [68,69]. Soya oil promoted highest biomass yield (1.11 g/50 ml) followed by Tween 80 (0.98 g/50 ml).…”

Respiratory pathways and oxygen toxicity inPhanerochaete chrysosporium

“…From these data we can conclude that mitochondrial function became impaired in cultures maintained on glucose, in line with the decline in rate of oxygen uptake that was measured, which is consistent with the increasingly reduced nature of intracellular compartments prior to lignin peroxidase expression [25]. In turn, anaerobic metabolism must represent the main route for ATP synthesis to maintain the constant energy charge observed.…”