Influence of Veratryl Alcohol and Hydrogen Peroxide on Ligninase Activity and Ligninase Production by Phanerochaete chrysosporium

Abstract

Veratryl alcohol, added as a supplement to cultures of Phanerochaete chrysosporium, enhanced ligninase activity through protection of the ligninase against inactivation by hydrogen peroxide produced by this fungus in cultures. In the presence of veratryl alcohol, the loss of ligninase activity observed in non-proteinsynthesizing cultures (cycloheximide-treated) equaled the extracellular protein turnover. When cultures were not supplemented with veratryl alcohol, inactivation of ligninase by hydrogen peroxide added to protein turnover, resulting in a more rapid loss of ligninase activity. Although all ligninase isoenzymes are sensitive to inactivation by hydrogen peroxide, only the isoenzyme of the highest specific activity (80.6 nkat mg of protein-'; Mr, 41,800; pl, 3.96) was found to be protected by veratryl alcohol. The concentration of veratryl alcohol necessary for full protection of ligninase activity varied according to the concentration of hydrogen peroxide present in the medium, which depended on the nature of the carbon source (glucose or glycerol). It is proposed that the nature of the carbon source influences the overall ligninase activity not only directly, by affecting the rate and the type of synthesized ligninase, but also by affecting the rate of hydrogen peroxide production, bringing about different rates of inactivation.

Potential of ligninolytic enzymatic complex produced by white‐rot fungi from genus Trametes isolated from Bulgarian forest soil

“…Similar data have been published on LiP activity of Coriolopsis gallica cultivated in the presence of Tween 80 [55]. Tonon and Odier [56] and Valli et al [57] suggested that veratryl alcohol does not stimulate higher enzyme activity by inducing de novo protein synthesis, but protects the enzyme from inactivation by excess H 2 O 2 produced by the fungus in the culture. Obviously, the effect of the widely used inducers on ligninolytic enzyme production depends on several factors and each strain responds in a particular way to each of these factors.…”

Extracellular enzyme activities during humic acid degradation by the white rot fungi Phanerochaete chrysosporium and Trametes versicolor

“…Considering the negative results obtained with veratryl alcohol when T. t'ersicolor was grown in the absence of humic acids, this compound seems to act as a mediator in the oxidation reactions catalysed by peroxidases [25][26][27] or as a preventive agent of enzymes from H.,O2-mediated inactivation [13,28,29] rather than as an inducer of the ligninolytic system [12,30]. In the presence of humic acids, veratryl alcohol induces an increase in peroxidase activities of both fungi, with no corresponding increase in humic acid decolorization.…”

“…intermediates [10] whereas MnP oxidizes Mn 2+ into Mn 3÷, which is the effective agent involved in the oxidation of phenolic units of lignin [11]. The effect of veratryl alcohol, known to be an enhancer of the ligninolytic system [12,13], was also investigated.…”

On a revised mechanism of side product formation in the lignin peroxidase catalyzed oxidation of veratryl alcohol

“…A schematic representation of the commonly accepted reaction mechanism that accounts for product formation from VA (1) is depicted in Scheme 1. LiP oxidizes VA to the corresponding radical cation (VA , 1a) which may lose a proton to form a radical that is oxidized further by LiP to VAD (2).…”