Efficient production of optically pure D-lactic acid from raw corn starch by using a genetically modified L-lactate dehydrogenase gene-deficient and alpha-amylase-secreting Lactobacillus plantarum strain.
In order to achieve direct and efficient fermentation of optically pure D-lactic acid from raw corn starch, we constructed L-lactate dehydrogenase gene (ldhL1)-deficient Lactobacillus plantarum and introduced a plasmid encoding Streptococcus bovis 148 alpha-amylase (AmyA). The resulting strain produced only D-lactic acid from glucose and successfully expressed amyA. With the aid of secreting AmyA, direct D-lactic acid fermentation from raw corn starch was accomplished. After 48 h of fermentation, 73.2 g/liter of lactic acid was produced with a high yield (0.85 g per g of consumed sugar) and an optical purity of 99.6%. Moreover, a strain replacing the ldhL1 gene with an amyA-secreting expression cassette was constructed. Using this strain, direct D-lactic acid fermentation from raw corn starch was accomplished in the absence of selective pressure by antibiotics. This is the first report of direct D-lactic acid fermentation from raw starch.
Okano
Kenji
K
Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan.
Zhang
Qiao
Q
Shinkawa
Satoru
S
Yoshida
Shogo
S
Tanaka
Tsutomu
T
Fukuda
Hideki
H
Kondo
Akihiko
A
D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D005285:Fermentation; D017353:Gene Deletion; D005947:Glucose / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000235:genetics*; D019344:Lactic Acid / Q000378:metabolism*; D048191:Lactiplantibacillus plantarum / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D013213:Starch / Q000378:metabolism*; D016985:Streptococcus bovis / Q000235:genetics; D003313:Zea mays / Q000378:metabolism; D000516:alpha-Amylases / Q000096:biosynthesis*
D001426:Bacterial Proteins; D019344:Lactic Acid; D013213:Starch; D007770:L-Lactate Dehydrogenase; D000516:alpha-Amylases; D005947:Glucose