Development and bioreactor testing of an evolutionary engineered strain of thermotolerant and xylose-utilizing Saccharomyces cerevisae for biofuel ethanol production

Date

6-2016

Degree

Bachelor of Science in Chemical Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Catalino G. Alfafara

Abstract

Evolutionary engineering, via the Genome Shuffling Method (GSM), was used to improve ethanol production of an existing thermotolerant and xylose-utilizing strain of Saccharomyces cerevisiae CMM044, for biofuel-ethanol production applications. The putative improved strain was then used for optimization of fermentation conditions (via Response Surface Methodology, RSM) in flask culture , and then further tested for batch growth and ethanol fermentation kinetics in a stirred tank bioreactor. Electroporation was done on electrocompetent cells of strain CMM044, in order to induce incorporation of DNA (containing the desired xylose-utilization genes) from Pichia stipitis NRRL7124. Then, colonies of the electroporated cells (grow under selective pressure) were obtained and screened for ethanol and residual xylose concentrations. GSM application of the parent CMM044 strain resulted in the successful development of the putative improved strain 1, which had 33% higher ethanol production. The experimentally verified optimum fermentation condition to maximize ethanol concentration were found to be: (a) 35 °C temperature, (b) 8% (w/v) initial xylose concentration, and (c) initial cell density of 2.0 (absorbance). Further troubleshooting on bioreactor operations, as well as in the use of actual lignocellulosic hydrolysate, is recommended to address problems on low inoculum size, high cell viability, and adequate anaerobic conditions for the fermentation runs.

Language

English

Location

UPLB College of Engineering and Agro-Industrial Technology (CEAT)

Call Number

LG 993.5 2016 E62 P46

Document Type

Thesis

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