Efficient homo d-lactic acid production from xylose
Kenji OKANO2009, Journal of Bioscience and Bioengineering
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Abstract
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-amylase from a Streptococcus bovis 148 (AmyA)-secreting plasmid. 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, 73.4 g/l of lactic acid was produced with high yield (0.85 g/g of consumed sugar) and an optical purity of 99.6k. Moreover, a strain substituting 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.
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