Journal of Food Processing & Technology

Designer host for cellulosic ethanol production via synthetic biology

2^nd International Conference and Exhibition on Food Technology, Bioprocess & Cell Culture

October 28-30, 2013 Kansas City Marriott Country Club Plaza, USA

Jui-Jen Chang, Yueh-Chin Wu, Yu-Han Hou, Chieh-Chen Huang, Ming-Che Shih and Wen-Hsiung Li

Scientific Tracks Abstracts: J Food Process Technol

Abstract:

To achieve economical biofuel production, such as cellulosic ethanol, a host that can do both cellulosic saccharification and ethanol fermentation is desirable. However, to engineer a non-cellulolytic microbe to be such a host requires synthetic biology techniques to pursue large-scale genomic engineering of the host. We have developed an efficient high-throughput method that can simultaneously introduce many genes into a genome. It is called Promoter-based gene assembly and simultaneous overexpression (PGASO). PGASO was applied to transform multiple cellulase genes into the genome of Kluyveromyces maxianus KY3 with a single selection marker gene. Six genes of different GH families were cloned from the cellulolytic fungi Trichoderma, Aspergillus, and Neocallimastix. The recombinant strain is capable of co-expressing a cellulase cocktail and can directly convert microcrystalline cellulose to ethanol. Our study shows that a designer yeast can be developed to simultaneously express different GH genes, and our enzyme cocktail shows a synergistic effect of these enzymes in digesting cellulose. Thus, PGASO can serve as a platform to study enzyme synergism in a single host and can be used to construct a host for a cell factory for enzyme production. In addition, KY3 can be co-cultured with bacterial hosts. A designer Bacillus subtilis that carries eight cellulosomal genes of Clostridium thermocellum, including one scaffolding protein gene, one cell-surface anchor gene, and six cellulase genes, was constructed and employed as a partner of KY3 for cellulosic bioethanol production. A novel dual-microbe co-culture system is developed to improve bioethanol production.