There was no report concerning the production of mycelial biomass of P. pulmonarius harvested from an automated bioreactor for the production of liquid spawn and adaptation on rubber wood sawdust. Frieal and McLoughlin (2000) reported on the advantages of liquid spawn of Lentinus sp. compared to grain spawn such as providing more uniform distribution, more stringent aseptic conditions, and rapid production of fruiting body compared to grain spawn. However, the cultivators need to know the nutritional requirements of mushroom in order to produce good quality liquid spawn. Zou (2005), reported that nutritional requirement of mushroom was one of the pre-requisites for mycelial growth of Oudemansiella radicata in submerged cultures. Generally, carbon and nitrogen play a significant role because these nutrients are important to the yield of any fermentation products. Good quality liquid spawn also shows rapid, high density and reliable growth on a given substrates when used in mushroom cultivation ( Smith et al., 2002).