Effect of lactose on soluble glucan production and on the ultrastructure of Sclerotium rolfsii Sacc. Grown in submerged culture

A significant increase in mycelial dry weight and a decrease in production of extracellular glucan were observed when lactose was added to a submerged culture of Sclerotium rolfsii grown in a liquid glucose synthetic medium. When added as a sole carbon source, lactose at 2.5% (w/v) induced the formation of dark, spherical, compact bodies. The ultrastructure of these bodies is compared with that of sclerotia formed on solid media.