Ethanol Productivity of Candida tropicalis ATTCa Using Repeated-Batch Fermentation System

Nurul Faseeha, Binti Zulkiffli (2015) Ethanol Productivity of Candida tropicalis ATTCa Using Repeated-Batch Fermentation System. Masters thesis, Universiti Malaysia Sarawak (UNIMAS).

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Abstract

Repeated-batch fennentation (RBF) mode was used as a method since the main aim is to enhance fennentation efficiency by increasing the ethanol productivity. The results obtained shows that Candida tropicalis ATTCa can be classified as thennotolerant yeast strain due to its ability to grow at temperature higher than 42°C, in fact it can survive up to 51 0c. Thennotolerant yeast strains give several advantages such as energy savings through reduced cooling costs, higher saccharification and fennentation rates, continuous ethanol removal and reduced contamination. Studies on effect of initial glucose concentration showed that the use of high glucose concentration for the initial cycles would affect the fennentation efficiency and cells viability as the cycles increased. The repeated-batch fennentation (RBF) using commercialized glucose as a substrate was successfully perfonned until 14th cycles with the highest fennentation efficiency, volumetric productivity and ethanol yield of 89%, 1.81 gr'h and 0.454, respectively. The highest glucose concentration applied was 200 gil, suggesting that this strain could tolerate with high osmotic environment. Studies on pH profile shows that the strain grows at pH ranged from 3.59 to 5.65 and the pH pattern was maintained throughout the process. Studies also revealed that this strain able to ferment sugar produced from hydrolyzed sago starch (HSS) at nonconventional temperature with a total of 10 successful fermentation cycles.

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