Effect of cultivation conditions on ligninolytic enzyme production by Ganoderma carnosum

Abstract

Ganoderma carnosum has been found in Europe only, at coniferous trees and it is difficult to distinguish it morphologically from G. lucidum. Since G. carnosum has not been studied biochemically yet, the aim of this study was to analyse its ability to produce Mn-dependent peroxidase (MnP), versatile peroxidase (VP) and laccase (Lac) under conditions of solid-state fermentation of selected plant raw materials as carbon sources, in the presence of different nitrogen concentrations in the medium. Wheat straw, corn stem, oak and grapevine sawdust were the analysed plant raw materials. Nitrogen source in synthetic medium was NH4NO3 and its concentrations were: 10mM N and 20 mM N. Enzyme activity was determined spectrophotometrically, using ABTS and phenol red, as the substrates for Lac and Mn-oxidizing peroxidases, respectively. Maximum level of MnP activity (56.82 U/l) was obtained in the medium with wheat straw and nitrogen concentration of 10 mM. Best carbon source for VP production was grapevine sawdust at nitrogen concentration of 10 mM (80.80 U/l). The obtained Lac activity was very low in the medium with wheat straw (1.80 U/l), while it was not detected in the presence of other three analyzed plant raw materials. Maximum of total protein content (0.06 mgml-1) was noted in the medium where oak sawdust was carbon source and nitrogen concentration was 20 mM.Vrste roda Ganoderma su producenti mnogih biološki aktivnih supstanci pa su objekti proučavanja mnogih medicinskih i farmaceutskih studija. U novije vreme se sve više pažnje poklanja upoznavanju njihovog ligninolitičkog enzimskog sistema, u cilju uspešne primene u različitim biotehnološkim procesima. Za razliku od G. lucidum, čiji je ligninolitički sistem intenzivno proučavan, ostale vrste ovog roda su retko bile objekti istraživanja. G. carnosum se teško morfološki razlikuje od G. lucidum. i još uvek nije biohemijski proučena, pa je cilj našeg istraživanja bio analiza produkcije Mn-oksidujućih peroksidaza i lakaza u uslovima čvrste kultivacije, na različitim biljnim ostacima (pšenična slama, stabljike kukuruza, piljevina hrasta i vinove loze) u prisustvu azota u obliku NH4NO3 i u koncentracijama od 10 mM, odnosno 20 mM. Maksimum produkcije Mn-zavisne peroksidaze dobijen je na pšeničnoj slami pri koncentraciji azota od 10 mM (56.82 U/l). Piljevina vinove loze i koncentracija azota od 10 mM bili su optimalni za sintezu verzatil peroksidaze (80.80 U/l). Dobijena aktivnost lakaza je bila izuzetno niska u medijumu sa pšeničnom slamom (1.80 U/l), dok na ostalim biljnim ostacima nije zabeležena. Maksimalni sadržaj ukupnih proteina je bio najveći u medijumu sa piljevinom hrasta kao izvorom ugljenika i koncentracijom azota od 10 mM.Projekat ministarstva br. 14304