Methanol as alternative carbon source for quicker efficient production of the microalgae Chlorella minutissima: Role of the concentration and frequence of administration

Autotrophic cultures of the marine microalgae Chlorella minutissima were pe rformed at 13000 lux continuous illumination in 1 1 chambers fertilised wit h 0.25 g l(-1) F2 medium and different doses of methanol. This was administ ered in two ways during two parallel experimental series of 10 days: 0.05, 0.1, 0.5, 1.0 and 5.0% methanol (v/v) in one unique dose at the beginning o f the culture and 1/10 of these (i.e. 0.005, 0.01, 0.05, 0.1 and 0.5% metha nol (v/v)) in daily doses for the 10-day culture period. Low concentrations of methanol induced a faster increase of cell density and dry weight than control, while high concentrations induced symptoms of toxicity. The higher cell densities and quicker growth were observed in the experiments with da ily administration of 0.005 and 0.1% (v/v) methanol, while those with one d ose presented an initial boosted growth but a final cell density lower than control. The role of methanol as alternative carbon source for microalgae, as well as its possible impact on the quality of biomass production and on the environment, are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.