Transformant and process for production thereof, and process for production of lactic acid
The present invention relates to a transformant which uses Schizosaccharomyces pombe as a host into which a D-LDH gene derived from bacteria of the genus Pediococcus and a D-LDH gene derived from bacteria of the genus Lactobacillus are incorporated and in which some of the genes in a group of pyruvate decarboxylase-encoding genes of the Schizosaccharomyces pombe host have been deleted or inactivated.
1. A Schizosaccharomyces pombe transformant into which a D-lactate dehydrogenase gene of bacteria of Pediococcus acidilactici and a D-lactate dehydrogenase gene of bacteria of Lactobacillus bulgaricus or Lactobacillus brevis are incorporated,
wherein pyruvate decarboxylase 2-encoding genes of the Schizosaccharomyces pombe transformant have been deleted or inactivated.
2. The Schizosaccharomyces pombe transformant according to claim 1 ,
wherein the D-lactate dehydrogenase gene of bacteria of Pediococcus acidilactici and the D-lactate dehydrogenase gene of bacteria of Lactobacillus bulgaricus or Lactobacillus brevis are incorporated into a chromosome of the Schizosaccharomyces pombe transformant.
3. A process for production of a Schizosaccharomyces pombe transformant into which a D-lactate dehydrogenase gene of bacteria of Pediococcus acidilactici and a D-lactate dehydrogenase gene of bacteria of Lactobacillus bulgaricus , or Lactobacillus brevis are incorporated and in which pyruvate decarboxylase 2-encoding genes of the Schizosaccharomyces pombe transformant have been deleted or inactivated, the process comprising:
a step of obtaining a transformant by introducing an expression cassette into a Schizosaccharomyces pombe host,
wherein the expression cassette consists of an expression cassette including a promoter and a terminator functioning in the Schizosaccharomyces pombe host and a D-lactate dehydrogenase gene of bacteria of Pediococcus acidilactici and an expression cassette including a promoter and a terminator functioning in the Schizosaccharomyces pombe host and a D-lactate dehydrogenase gene of bacteria of Lactobacillus bulgaricus or Lactobacillus brevis , or consists of an expression cassette including a promoter or a terminator functioning in the Schizosaccharomyces pombe host, a D-lactate dehydrogenase gene of bacteria of Pediococcus acidilactici , and a D-lactate dehydrogenase gene of bacteria of Lactobacillus bulgaricus or Lactobacillus brevis , and
the Schizosaccharomyces pombe host in which pyruvate decarboxylase 2-encoding genes have been deleted or inactivated, or
pyruvate decarboxylase 2-encoding genes of the obtained transformant are deleted or inactivated.
4. The process for production of a Schizosaccharomyces pombe transformant according to claim 3 ,
wherein the D-lactate dehydrogenase gene of bacteria of Pediococcus acidilactici and the D-lactate dehydrogenase gene of bacteria of Lactobacillus bulgaricus or Lactobacillus brevis are introduced into a chromosome of the Schizosaccharomyces pombe host.
5. The process for production of lactic acid,
wherein a Schizosaccharomyces pombe transformant of claim 1 is cultured or fermented in a culture solution or a fermentation solution, and
D-lactic acid is obtained from the culture solution or the fermentation solution.
6. The process for production of lactic acid according to claim 5 ,
wherein the culture or the fermentation is performed using a culture solution or a fermentation solution containing glucose or sucrose at a concentration of 1% by mass to 50% by mass.
7. The process for production of lactic acid according to claim 5 ,
wherein the culture or the fermentation is further continued after the pH of the culture solution or the fermentation solution becomes equal to or less than 3.5 due to the D-lactic acid produced by the Schizosaccharomyces pombe transformant.
8. The process for production of lactic acid according to claim 5 ,
wherein an initial bacterial cell concentration of the Schizosaccharomyces pombe transformant in the culture solution or the fermentation solution is set to be 0.1 g /L to 50 g/L (expressed in terms of dry bacterial cells).
9. The process for production of lactic acid according to claim 5 ,
wherein the culture or the fermentation is continued without neutralizing the D-lactic acid in the culture solution or the fermentation solution that is produced by the Schizosaccharomyces pombe transformant.
10. The process for production of lactic acid according to claim 5 ,
wherein lactic acid is separated from the culture solution or the fermentation solution without neutralizing the D-lactic acid in the culture solution or the fermentation solution that is produced by the Schizosaccharomyces pombe transformant.