An investigation of characteristics of Trichoderma spp. which are distributed in bed log cultivation houses of shiitake mushroom in Hokkaido

Abstract

To understand the fungal contamination of culture facilities for the bed log cultivation of shiitake (Lentinula edodes) in Hokkaido, we examined airborne fungi in four plastic greenhouses by the use of plates made of PDA (potato dextrose agar) from June to October once a month in 2005.Furthermore, antifungal effects of benomyl (BEN) and thiabendazole (TBZ) on 74 isolates of Trichoderma spp. collected from airborne fungi were studied. The results obtained were as follows:

(1) The mean value of airborne microorganisms in the four plastic greenhouses (for the fruiting and the rest of the bed logs) was 30.8 CFU (colony forming unit)/plate of diameter 90 mm (the value of fungi was 25.9 CFU/plate, the value of bacteria was 4.5 CFU/ plate, the value of yeasts was 0.4 CFU/plate).

(2) Mycelia Sterilia (MS), the most dominant fungi, accounted for 36.1% the total colonies, followed by Penicillium spp. (25.5%), Cladosporium spp. (23.2%), Aspergillus spp. (5.5%), Trichoderma spp. (4.2%) and others in the two houses for fruiting of the bed logs.

(3) The mycelial growth of 56 isolates of Trichoderma spp. which was isolated from the airborne fungi was inhibited completely on PDA plates containing 0.01%(w/v) of BEN. On the other hand, the three isolates of Trichoderma spp. (including ANCT-05090) grew up vigorously on the plates.

(4)MIC (Minimum Inhibitory Concentration) against ANCT-05090 exceeded 1% (w/v) of BEN,and was 1%(w/v) of TBZ.