The effects of bisulfite and sulfite on the growth of Botryococcus braunii have been studied. At low concentrations (0-1 mmol/l), bisulfite had no adverse influence on the growth of B. braunii and the formed sulfate from bisulfite by oxidation was utilized as a sulfur source supporting cell concentration and cell growth rate equal to those found in the control culture using the same concentration of sulfate as a sulfur source. However, bisulfite was toxic to the alga at high concentrations (>1 mmol/l). The structure of hydrocarbons produced by B. braunii on different S-sources showed no significant differences. The same held for sulfite, but the toxicity of sulfite was weaker than that of bisulfite. (C) 2004 Elsevier Inc. All rights reserved.