Co-expression of two heterologous lactate dehydrogenases genes in Kluyveromyces marxianus for L-lactic acid production

Jae Won Lee, Jung Hoon In, Joon Bum Park, Jonghyeok Shin, Jin Hwan Park, Bong Hyun Sung, Jung Hoon Sohn, Jin Ho Seo, Jin Byoung Park, Soo Rin Kim, Dae Hyuk Kweon

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Lactic acid (LA) is a versatile compound used in the food, pharmaceutical, textile, leather, and chemical industries. Biological production of LA is possible by yeast strains expressing a bacterial gene encoding L-lactate dehydrogenase (LDH). Kluyveromyces marxianus is an emerging non-conventional yeast with various phenotypes of industrial interest. However, it has not been extensively studied for LA production. In this study, K. marxianus was engineered to express and co-express various heterologous LDH enzymes that were reported to have different pH optimums. Specifically, three LDH enzymes originating from Staphylococcus epidermidis (SeLDH; optimal at pH 5.6), Lactobacillus acidophilus (LaLDH; optimal at pH 5.3), and Bos taurus (BtLDH; optimal at pH 9.8) were functionally expressed individually and in combination in K. marxianus, and the resulting strains were compared in terms of LA production. A strain co-expressing SeLDH and LaLDH (KM5 La + SeLDH) produced 16.0 g/L LA, whereas the strains expressing those enzymes individually produced only 8.4 and 6.8 g/L, respectively. This co-expressing strain produced 24.0 g/L LA with a yield of 0.48 g/g glucose in the presence of CaCO3. Our results suggest that co-expression of LDH enzymes with different pH optimums provides sufficient LDH activity under dynamic intracellular pH conditions, leading to enhanced production of LA compared to individual expression of the LDH enzymes.

Original languageEnglish
Pages (from-to)81-86
Number of pages6
JournalJournal of Biotechnology
Volume241
DOIs
StatePublished - 10 Jan 2017

Keywords

  • Co-expression
  • Kluyveromyces marxianus
  • Lactate dehydrogenase
  • Lactic acid
  • Optimal pH

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