Detection of highly productive strains of Pleurotus ostreatus by their tolerance to 2-deoxy-D-glucose in starch-based media

Abstract

An identification procedure for fast fructifying strains of Pleurotus ostreatus was developed using maize starch as carbon source, mineral salts and 0·1 g l −1 2-deoxy- d -glucose (2-DG). Three strains that grew on Petri dishes in these conditions were called 2-DG tolerant. In trials under normal farming conditions, tolerant strains fruited an average of 19 days faster and had a mean productivity (g daily yield of edible mushrooms kg −1 of compost raw material) which was twice that of three other strains that were 2-DG sensitive in growth tests in vitro . Analysis of mycelial morphology indicated that with starch as main carbon source increasing concentrations of 2-DG reduced the hyphal diameter ( D h ) and length of distal hyphal segments ( L av ) in all strains. On media containing glucose as main carbon source the D h of the tolerant strains was only 60% of that of the sensitives, and the D h of tolerant strains increased an average 53 % with addition of 0·01 g l −1 of 2-DG. The hyphal diameter of sensitive strains tended to decrease when 2-DG was added to the glucose-based culture medium. L av showed no regular pattern among strains. The 2-DG tolerant phenotype in maize starch medium may be a useful phenotype for selection of highly productive strains of P. ostreatus for commercial exploitation. Its physiological basis is unclear, but the observed changes in hyphal diameter suggest that sublethal concentrations of the glucose analogue may stimulate mycelial growth of tolerant strains in some way.