Modification to a Semi-selective Medium for the Isolation and Quantification of the Nematophagous Fungus of Pochonia chlamydosporia

摘要

Semi-selective media are valuable tools for detection and isolation of viable fungal propagules. After testing the in vitro sensitivity of Pochonia chlamydosporia to 9 different fungicidal compounds, boscalid and thiophanate-methyl were chosen for a modification of Kerry’s semi-selective agar. Rifampicin replaced tetracyclin to provide superior suppression of bacterial growth. The Pc medium contained 17 g/L corn meal agar, 17.5 g/L (NaCl), 75 mg/L Rose Bengal, 50 mg/L boscalid, 30 mg/L thiophanate-methyl, 50 mg/L rifampicin, 50 mg/L streptomycin sulphate, 50 mg/L chloramphenicol, 3 mL/L Triton X-100. Dilution plating of soil extracts from various California field soils amended with chlamydospores of P. chlamydosporia showed the modified medium was equivalent to Kerry’s agar in enumerating viable propagules of the fungus. While P. chlamydosporia colonies grew slower on the Pc medium, the fungal colonies appeared more uniform than on the original semi-selective agar.