Production of phenol-oxidizing enzymes in the interaction between white-rot fungi

Abstract

tified antifungicides. Production and localization of phenoloxidizing enzymes were specific in each dual culture; however, the results differed depending on the pairing of confronted fungi, and no predominance was observed because not all pairings were checked. Here, we used five white-rot fungi that are commonly seen in Japan and examined all pairings of fungus-to-fungus interaction, in accordance with the procedures described by White and Boddy (1992).Five strains of white-rot fungi that are preferential to angiospermous wood were tested: Ganoderma applanatum (Pers.) Karst. (KPUF 0694), Pleurotus ostreatus (Jacq.: Fr.) Kummer (KPUF 2494), Pycnoporus coccineus (Fr.) Bond. et Sing. (KPUF 2094), Schizophyllum commune Fr.: Fr. (KPUF 8805), and Trametes versicolor (L.: Fr.) Quel. (IFO 30340). Dual culture tests of fungus pairs were performed with initial seeding at 5-cm distance on MA media (malt extract, 2%; agar 1.5%) at 28°C. MA medium was used to experiment with the interactive behavior of wood-rotting fungi because the behavior in this culture correlates well with their patterns of occurrence in the field (Griffith and Boddy 1991). After the predominance in confrontation was observed, the localities of laccase and peroxidase were determined by pouring substrate solutions (1.44% a-naphtol in 96% aqueous ethanol, and a mixture of 1% pyrogarol and 0.4% H 2 O 2 , respectively) on the culture plates in accordance with White and Boddy (1992). Figure 1 shows a result of the dual culture with P. ostreatus and S. commune. After confrontation occurred between them, the P. ostreatus colony grew over S. commune and then stopped after expanding into the colony a few millimeters. In most cases, one fungus grew over the other after confrontation and invaded to about 1-2 cm in depth. However, mycelia stopped growing in all cases except for the dual culture of T. versicolor and S. commune, where the former overgrew the latter. In the competition between T. versicolor and P. coccineus, both fungi stopped growing within a few millimeters of the confrontation regions, and mycelia of both became hypertrophic. These observations are summarized in Table 1. Porter (1924) classified the interaction between two fungi into five types. AbstractThe role of the phenol-oxidizing enzymes, laccase and peroxidase, was examined in the fungus-to-fungus interaction in dual cultures. Among five white-rot fungi, the following predominance in competition was observed: Pleurotus ostreatus > Trametes versicolor м Pycnoporus coccineus > Ganoderma applanatum > Schizophyllum commune. Both phenol-oxidizing enzyme activities were detected markedly at the confrontation region, and under the mycelia growing over other colonies more than in other areas of the dual culture. This property was most notably observed in the P. ostreatus cultures. The fungi that produce superior active phenol-oxidizing enzymes were predominant in the competition between confronting fungi, indicating that phenol-oxidizing enzymes relate to fungusto-fungus interaction.Key words Fungus...

Ecology of ligninolytic fungi associated with leaf litter decomposition

“…These include synergic, neutral, and competitive and antagonistic interactions, of which competitive and antagonistic interactions are the most important for the development of fungal communities (Rayner and Webber 1984). Studies on wood-decomposing fungi have shown that (White and Boddy 1992;Savoie et al 1998;Tsujiyama and Minami 2005). It is uncertain, however, whether similar results would be expected for mycelial interactions between ligninolytic litter-decomposing fungi.…”

Growth and Conidiation Response of Escovopsis weberi (Ascomycota: Hypocreales) Against the Fungal Cultivar of <I>Acromyrmex lundii</I> (Hymenoptera: Formicidae)

“…Also, we could possibly explain an increase in conidiation in the presence of the cultivar by Escovopsis using cultivar resources (i.e., nutrients derived from hyphae destruction, Reynolds and Currie 2004). Many fungi produce secondary metabolites that are used for their own defense or attack (Demain 1986), and some of these have been coopted by other organisms to their own advantage (Sonnenbichler et al 1994), mediate fungalÐfungal interactions, or both (White and Boddy 1992, Savoie et al 1998, Tsujiyama and Minami 2005. We believe this could be the case in the studied system.…”

“…Factors, such as carbon sources, NH 4 ϩ availability, or presence of particular metabolic precursors, seem to be involved in inducing chemical compounds in fungi (Demain 1986). In many cases, production of secondary metabolites and induction of conidiation can result from fungalÐfungal interactions (White and Boddy 1992, Savoie et al 1998, Whipps 2001, Tsujiyama and Minami 2005. Understanding how fungi, as biological control agents, respond to other microorganisms, including the target to be controlled (i.e., in this case fungus cultivar of the ants), is a prerequisite for any strategy to be used.…”

Mathematical model for Trametes versicolor growth in submerged cultivation

“…The enzyme production by white-rot fungi using different methods of submerged and solid-state cultivation has been intensively studied [3,[9][10][11][12][13][14][15][16]. Although there is an increasing interest in using these fungal cultures, there is little published data of the growth of white-rot fungi [17,18], mostly due to the difficulty of measuring the biomass concentration [19].…”