Mycelial growth requirements of Lactarius pyrogalus and Lactarius controversus

Abstract

The objective of this study was to determine the requirements including culture medium, temperature, pH,
carbon and nitrogen sources for the best mycelium growth of Lactarius pyrogalus and Lactarius
controversus. Different inoculum media containing peat and peat : vermiculite mixtures (1:4, 1:6, 1:8 and
1:10 v:v) were also investigated for vegetative inoculum production. In terms of mycelium growth rate and
mycelial characteristics, the most suitable culture media were potato dextrose agar and biotin aneurin
folic acid agar for L. pyrogalus and L. controversus. Although L. pyrogalus had higher mycelium growth
rate than L. controversus, they showed similar trend at different temperature. 25°C and 4.5 to 6.0 pH
values gave the best results for mycelial growth of these mushrooms. Mannitol, glucose, dextrose and
maltose were the most suitable carbon sources for L. pyrogalus, while mannitol, and lactose were the best
carbon sources for L. controversus and significantly enhanced mycelial growth. Malt extract, peptone,
yeast extract and Ca(NO3)2 were found to be the most suitable nitrogen sources for both Lactarius
species, except for peptone in L. controversus. The lowest mycelial growth was determined in xylose
among carbon sources, and NH4NO3 and (NH4)2HPO4 among nitrogen sources for both Lactarius species.
Peat : vermiculite mixtures in the rate of 1:4 and peat were the most suitable vegetative inoculum medium
for L. pyrogalus and L. controversus, respectively, when the mycelium growth rate and days to complete
mycelium running took into consideration.