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

Appl Environ Microbiol. 2009 Jan;75(2):462-7. doi: 10.1128/AEM.01514-08. Epub 2008 Nov 14.

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 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / biosynthesis*
  • Bacterial Proteins / genetics
  • Fermentation
  • Gene Deletion
  • Glucose / metabolism
  • L-Lactate Dehydrogenase / genetics*
  • Lactic Acid / metabolism*
  • Lactobacillus plantarum / enzymology*
  • Lactobacillus plantarum / genetics
  • Lactobacillus plantarum / metabolism*
  • Plasmids
  • Starch / metabolism*
  • Streptococcus bovis / genetics
  • Zea mays / metabolism
  • alpha-Amylases / biosynthesis*

Substances

  • Bacterial Proteins
  • Lactic Acid
  • Starch
  • L-Lactate Dehydrogenase
  • alpha-Amylases
  • Glucose