Differential expression of manganese peroxidase and laccase in white-rot fungi in the presence of manganese or aromatic compounds

Abstract

White-rot fungi (basidiomycetes) play an important role in the degradation of lignin which is, beside cellulose, the major compound of wood. This process is catalyzed by ligninolytic enzymes, which are able to cleave oxidatively aromatic rings in lignin structure. Manganese peroxidase and laccase of white-rot-fungi are the most important of these among the ligninolytic enzymes. In addition, they are able to degrade xenobiotic aromatic polymers, persisting as environmental pollutants. Manganese and aromatic compounds have often been discussed as being inducers, enhancers or mediators of these ligninolytic enzymes. It is known that supplementing the growth medium with either Mn2+, veratryl alcohol or coal-derived humic acids leads to significantly enhanced extracellular ligninolytic activities. Measuring the amount of expressed mRNA of the two enzymes by quantitative RT-PCR provided evidence that the expression of manganese peroxidase was induced in the three tested white-rot fungi, Clitocybula dusenii b11, Nematoloma frowardii b19, and a straw-degrading strain designated i63-2. Laccase, on the other hand, was expressed in all three fungi with a significant basic activity even without inducer added. However, since the level of laccase mRNA was higher in cultures supplemented with any one of the tested inducers, we conclude that both manganese and the aromatic substances also increase the expression of laccase.

A novel approach for application of white rot fungi in wastewater treatment under non-sterile conditions: immobilization of fungi on sorghum

“…Most of the previous studies on the application of WRF for treatment of recalcitrant organopollutants have been conducted using defined media, based on the recommendations by Tien and Kirk [33]. Although the composition of this media has been slightly modified by some researchers in order to reduce the cost [34] or increase the enzyme activities [35,36], still easily degradable soluble carbon sources were used, which can be easily assimilated by bacteria and other microorganisms.…”

Enzymatic Staining for Detection of Phenol-Oxidizing Isozymes Involved in Lignin- Degradation by Lentinula edodes on Native-PAGE

“…This Lcc activity increased gradually after day 52 while MnP activity was completely suppressed. Lcc has been shown to be induced by aromatic compounds and metallic ions such as copper (Collins & Dobson, 1997;Saparrat et al, 2002;Scheel et al, 2000;Shutova et al, 2008;Soden & Dobson, 2001). Indeed, copper has been reported to be a strong laccase inducer in the white-rot fungi Pleurotus ostreatus (Palmier et al, 2000), Trametes pubescens (Galhaup & Haltrich, 2001;Galhaup et al, 2002), and T. versicolor (Collins & Dobson, 1997).…”

Bioremediation of Lindane by Wood-Decaying Fungi

“…Four days prior to lindane addition, veratryl alcohol, a fungal secondary metabolite, was added to fungal liquid cultures (fi nal concentration 2 mM) in order to induce the production of ligninolytic enzymes (Faison and Kirk, 1985;Faison et al, 1986;Scheel et al, 2000). Fungal cultures were grown for 26 days and lindane was added 10 minutes, two hours, six hours, one day, three days, and 21 days prior to the end of the experiment.…”

“…Laccase genes are transcribed at low constitutive levels in many basidiomycetous fungi (Cullen, 1997;Aro et al, 2005). The expression can be enhanced using inducers such as aromatic compounds, including degradation products of lignin, which also induce expression of other ligninolytic genes (Muñoz et al, 1997;Scheel et al, 2000).…”