Fermentative production of l-galactonate by using recombinant Saccharomyces cerevisiae containing the endogenous galacturonate reductase gene from Cryptococcus diffluens.
The GAR1 gene, encoding d-galacturonate reductase in Cryptococcus diffluens, was isolated, and the GAR1-expression plasmid was constructed by insertion of GAR1 downstream of the yeast constitutive promoter in the yeast-integrating vector. Recombinant Saccharomyces cerevisiae expressing C. diffluensd-galacturonate reductase from a genome integrated copy of the gene was cultured for use the conversion of d-galacturonic acid to l-galactonic acid. The optimum conditions for l-galactonic acid production were determined in terms of the initial concentration of d-galacturonic acid, fermentation pH, and mixed sugars. The following conditions yielded high efficiency in the conversion of d-galacturonic acid to l-galactonic acid in large-scale cultures: 0.1% initial d-galacturonic acid concentration, pH 3.5, and glucose as additional sugar. The aerobic condition was necessary for the conversion of d-galacturonic acid. Subculture of that recombinant was not showing to decrease of the d-galacturonic acid conversion rate even though it was repeated in ten generations. Culturing in scale-up, the conversion rate of d-galacturonic acid to l-galactonic acid was increased.
Division of Applied Life Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
Takeo
T
Matsubara
Division of Applied Life Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
Shohei
S
Hamada
Division of Applied Life Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
Ayaka
A
Wakabayashi
Division of Applied Life Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan. Electronic address: masyksd@biochem.osakafu-u.ac.jp.
Masao
M
Kishida
D000332:Aerobiosis; D003454:Cryptococcus / Q000201:enzymology / Q000235:genetics*; D005285:Fermentation / Q000235:genetics; D006603:Hexuronic Acids / Q000378:metabolism; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases / Q000235:genetics* / Q000378:metabolism*; D030781:Organisms, Genetically Modified; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D013400:Sugar Acids / Q000378:metabolism*
D006603:Hexuronic Acids; D013400:Sugar Acids; C012991:galactonic acid; C007819:galacturonic acid; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; C477073:D-galacturonate reductase
Cryptococcus diffluens; Galacturonate reductase; Saccharomyces cerevisiae; d-Galacturonate; l-Galactonate