Changes in activity of extracellular enzymes in dual cultures of Lentinula edodes and mycoparasitic Trichoderma strains.
OBJECTIVE
The main problem that arises during the cultivation of Lentinula edodes, the Asian Shiitake mushroom, is that the logs on which the cultivation is performed are contaminated by competing micro-organisms, especially Trichoderma spp. The aim of this study was to examine the changes in activity of extracellular enzymes in dual cultures of Trichoderma spp. and L. edodes.


RESULTS
Extracellular enzyme activities were determined spectrophotometrically. Trichoderma enzymes important for the degradation of fungal cell walls (N-acetyl-beta-glucosaminidase and laminarinase) were shown to be induced by inactive L. edodes mycelia in liquid culture. The changes that occurred in the extracellular enzyme activities of L. edodes and mycoparasitic Trichoderma spp. (T. aureoviride, T. harzianum and T. viride) were examined during antagonistic interactions on solid medium. The extracellular enzyme patterns of both partners proved to be altered. Trichoderma spp. were induced to produce N-acetyl-beta-glucosaminidase and laminarinase in the presence of active L. edodes mycelia, similarly as observed in liquid culture. The activities of both laccase and manganese peroxidase of L. edodes decreased after physical contact with active Trichoderma mycelia, possibly in consequence of the beginning of degradation of L. edodes by the Trichoderma enzymes. However, besides a decrease in manganese peroxidase activity, an enhancement of L. edodes laccase activity was observed on solid media containing crude culture fluids from Trichoderma liquid cultures. The metabolites responsible for these effects proved to be heat stable.


CONCLUSIONS
Induction and inhibition of several extracellular enzymes of both partners were shown in dual cultures of L. edodes and Trichoderma strains, indicating the important role of these enzymes in the antagonistic interaction between the two species.


CONCLUSIONS
As the main problem during the large-scale cultivation of L. edodes is the contamination of the growth substrate by Trichoderma mycelia, the particular knowledge of the mechanism of this competition might be relevant.
Hatvani
N
N
Institute for Biotechnology, Zoltan Bay Foundation for Applied Research, PO Box 2337, H-6701 Szeged, Hungary. hnora@bay-u-szeged.hu
Kredics
L
L
Antal
Z
Z
Mécs
I
I
D000898:Antibiosis; D003470:Culture Media; D004790:Enzyme Induction; D004693:Glucan Endo-1,3-beta-D-Glucosidase / Q000378:metabolism; D006596:Hexosaminidases / Q000378:metabolism; D020074:Lentinula / Q000201:enzymology* / Q000254:growth & development*; D014242:Trichoderma / Q000201:enzymology* / Q000254:growth & development*; D048828:beta-N-Acetyl-Galactosaminidase
D003470:Culture Media; D006596:Hexosaminidases; D004693:Glucan Endo-1,3-beta-D-Glucosidase; D048828:beta-N-Acetyl-Galactosaminidase