Coexpression of Lactobacillus brevis ADH with GDH or G6PDH in Arxula adeninivorans for the synthesis of 1-(R)-phenylethanol

Appl Microbiol Biotechnol. 2015 Jun;99(11):4723-33. doi: 10.1007/s00253-014-6297-z. Epub 2014 Dec 24.

Abstract

The yeast Arxula adeninivorans was used for the overexpression of an ADH gene of Lactobacillus brevis coding for (R)-specific alcohol dehydrogenase (LbADH) to synthesise enantiomerically pure 1-(R)-phenylethanol. Glucose dehydrogenase gene from Bacillus megaterium (BmGDH) or glucose 6-phosphate dehydrogenase of Bacillus pumilus (BpG6PDH) were coexpressed in Arxula to regenerate the cofactor NADPH by oxidising glucose or glucose 6-phosphate. The yeast strain expressing LbADH and BpG6PDH produced 5200 U l(-1) ADH and 370 U l(-1) G6PDH activity, whereas the strain expressing LbADH and BmGDH produced 2700 U l(-1) ADH and 170 U l(-1) GDH activity. However, the crude extract of both strains reduced 40 mM acetophenone to pure 1-(R)-phenylethanol with an enantiomeric excess (ee) of >99 % in 60 min without detectable by-products. An increase in yield was achieved using immobilised crude extracts (IEs), Triton X-100 permeabilised cells (PCs) and permeabilised immobilised cells (PICs) with PICs being most stable with GDH regeneration over 52 cycles. Even though the activity and synthesis rate of 1-(R)-phenylethanol with the BpG6PDH and LbADH coexpressing strain was higher, the BmGDH-LbADH strain was more stable over successive reaction cycles. This, combined with its higher total turnover number (TTN) of 391 mol product per mole NADP(+), makes it the preferred strain for continuous reaction systems. The initial non-optimised semi-continuous reaction produced 9.74 g l(-1) day(-1) or 406 g kg(-1) dry cell weight (dcw) day(-1) isolated 1-(R)-phenylethanol with an ee of 100 % and a TTN of 206 mol product per mole NADP(+). In conclusion, A. adeninivorans is a promising host for LbADH and BpG6PDH or BmGDH production and offers a simple method for the production of enantiomerically pure alcohols.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcohol Dehydrogenase / genetics
  • Alcohol Dehydrogenase / metabolism*
  • Bacillus / enzymology
  • Bacillus / genetics
  • Benzyl Alcohols / metabolism*
  • Gene Expression
  • Glucose 1-Dehydrogenase / genetics
  • Glucose 1-Dehydrogenase / metabolism*
  • Glucosephosphate Dehydrogenase / genetics
  • Glucosephosphate Dehydrogenase / metabolism*
  • Levilactobacillus brevis / enzymology*
  • Levilactobacillus brevis / genetics
  • Metabolic Engineering / methods*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Saccharomycetales / enzymology
  • Saccharomycetales / genetics
  • Saccharomycetales / metabolism*

Substances

  • Benzyl Alcohols
  • Recombinant Proteins
  • methylphenyl carbinol
  • Alcohol Dehydrogenase
  • Glucose 1-Dehydrogenase
  • Glucosephosphate Dehydrogenase