Ethanol production from Jerusalem artichoke by K. marxianus: influence of culture parameters on seed yeast quality

The influence of yeast extract (YE), cornsteep liquor (CSL), substrate concentration, shaking frequency of the incubator and the temperature on the seed yeast quality of K. marxianus (K. fragilis CCY 51-1-4) was studied by means of a 2 super(5)-factorial design. YE and CSL both had a positive effect on yeast yield and cellbound inulase activity. Addition of 1% CSL caused the same increase in yeast yield as 0.5% YE. The fermentation rate (measured as loss of weight after 21 h) was lower with CSL, but the ethanol yield after 48 h was the same as with YE. High shaking frequency (250 rpm) of the inoculum incubator had a positive effect on the yeast quality, whereas a temperature of 35 degree C and high substrate concentration (8%DM) had a negative influence on it.