Construction of a direct starch-fermenting industrial strain of Saccharomyces cerevisiae producing glucoamylase, alpha-amylase and debranching enzyme.
To develop a strain of Saccharomyces cerevisiae that produces ethanol directly from starch, two integrative vectors were constructed to allow the simultaneous multiple integration of the Aspergillus awamori glucoamylase gene (GA1) and the Debaryomyces occidentalis alpha-amylase gene (AMY) and glucoamylase with debranching activity gene (GAM1) into the chromosomes of an industrial strain of S. cerevisiae. The GA1 and AMY genes were constitutively expressed under the ADC1 promoter in S. cerevisiae using the double delta-integration system. The GAM1 gene was constitutively expressed under the corresponding promoter using the double 18S rDNA-integration system. The recombinant industrial strain secreting biologically active alpha-amylase, glucoamylase and debranching enzyme was able to ferment starch to ethanol in a single step. The new strain produced 8% (v/v) ethanol (62.8 g l(-1)) from 20% (w/v) soluble starch after 2 days, fermentation.
Department of Biological Sciences, College of Natural Sciences, Chonnam National University, Gwangju, 500-757, South Korea.
Ji-Hye
JH
Kim
Ha-Ram
HR
Kim
Mi-Hyeon
MH
Lim
Hyun-Mi
HM
Ko
Jong-Eon
JE
Chin
Hwanghee Blaise
HB
Lee
Il-Chul
IC
Kim
Suk
S
Bai
D001230:Aspergillus / Q000201:enzymology / Q000235:genetics; D000431:Ethanol / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005818:Genetic Engineering; D005822:Genetic Vectors; D005087:Glucan 1,4-alpha-Glucosidase / Q000235:genetics / Q000378:metabolism*; D006004:Glycogen Debranching Enzyme System / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D004718:Saccharomycetales / Q000201:enzymology / Q000235:genetics; D013213:Starch / Q000378:metabolism*; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism*
D005656:Fungal Proteins; D006004:Glycogen Debranching Enzyme System; D000431:Ethanol; D013213:Starch; D000516:alpha-Amylases; D005087:Glucan 1,4-alpha-Glucosidase