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Fermentation of molasses using a thermotolerant yeast, Kluyveromyces marxianus IMB3: simplex optimisation of media supplements

Gough, S., Flynn, O., Hack, C.J., Marchant, R.
Applied microbiology and biotechnology 1996 v.46 no.2 pp. 187-190
Kluyveromyces marxianus, ammonium sulfate, computers, ethanol, ethanol production, fatty acids, fermentation, heat tolerance, linseed oil, magnesium, magnesium sulfate, molasses, nitrogen, potassium, potassium dihydrogen phosphate, sucrose, yeasts
The use of molasses as a substrate for ethanol production by the thermotolerant yeast Kluyveromyces marxianus var. marxianus was investigated at 45 degrees C. A maximum ethanol concentration of 7.4% (v/v) was produced from unsupplemented molasses at a concentration of 23% (v/v). The effect on ethanol production of increasing the sucrose concentration in 23% (v/v) molasses was determined. Increased sucrose concentration had a similar detrimental effect on the final ethanol produced as the increase in molasses concentration. This indicated that the effect may be due to increased osmotic activity as opposed to other components in the molasses. The optimum concentration of the supplements nitrogen, magnesium, potassium and fatty acid for maximum ethanol production rate was determined using the Nelder and Mead (Computer J 7:308-313, 1965) simplex optimisation method. The optimum concentrations of the supplements were 0.576 g l-1 magnesium sulphate, 0.288 g l-1 potassium dihydrogen phosphate and 0.36% (v/v) linseed oil. Added nitrogen in the form of ammonium sulphate did not affect the ethanol production rate.