Ethanol Production from Cassava Pulp by a Newly Isolated Thermotolerant <i>Pichia kudriavzevii</i> LC375240

A total of 500 thermotolerant fermenting yeast isolates (100 from palm-wine and 400 from spoilt fruits) were screened for ethanol production at high temperatures. The best isolate that produced up to 4% ethanol from 10% glucose at 45°C was selected for further experiments. The optimum pH for ethanol production by the isolate was pH 6 at both 30°C and 42°C. The isolate was identified as Pichia kudriavzevii base on the 18s ribosomal DNA. Ethanol production from 200 g/L cassava pulp using Simultaneous Saccharification and Fermentation (SSF) method at 30°C and 42°C by the isolate was investigated. At 30°C, an ethanol concentration of 30 g/L was produced. This represents an ethanol yield of 0.15 g/g of cassava pulp and 58.8% of the theoretical yield. However at 42°C, the concentration of ethanol produced increased to 42 g/L representing an ethanol yield of 0.21 g/g of cassava pulp and 82.4% of the theoretical yield. The isolate produced slightly higher ethanol than the two typed strains NCYC 587 and NCYC 2791 at 42°C. This isolate has a good potential to be used for commercial bioethanol production since it can produce ethanol at 45°C without a significant drop in ethanol yield.