The effects of initial pH on simultaneous production of ganoderic acid and a polysaccharide by the fungus Ganoderma lucidum were investigated in shake flasks. An initial pH value, varying within the range of 3.5-7.0. had a significant effect on the cell growth and product biosynthesis. At an initial pH of 6.5, a maximum in biomass of 17.3 +/- 0.12 g/l by dry weight (DW) was obtained, as well as a maximal specific production of ganoderic acid of 1.20 +/- 0.03 mg/100 mg DW and total production of 207.9 +/- 2.7 mg/l. Lowering the initial pH from 6.5 to 3.5 gradually led to a higher production of extracellular polysaccharide and a higher specific production of intracellular polysaccharide. (C) 2002 Elsevier Science Ltd. All rights reserved.