Abstract

We have engineered strain BG-10 of the methylotrophic yeast Komagataella phaffii for use as an effective whole cell biocatalyst. We introduced into the yeast a transgene encoding a Chromobacterium violaceum omega-transaminase for transcription in response to methanol induction. The strain was then assessed with respect to its growth performance and biotransformation of a fed ketoalcohol substrate to an amino-alcohol. In the resultant strain, BG-TAM, methanol induction did not compromise cell growth. Successful bioconversion of fed substrates to the byproduct, acetophenone, indicated transaminase activity in shake flask-cultivated BG-TAM cells. We then used bioreactor cultivation to exploit the high levels of biomass achievable by Komagataella phaffii. In a 900 mu L reaction the BG-TAM strain at OD600 = 1024 achieved up to 0.41 mol mol(-1) (mol(product) mol(substrate)(-1)) yield on substrate (Yp/s) for production of 1-methyl-3-phenylpropylamine and a space time yield (STY) of 0.29 g L-1 h(-1) for production of 2-amino-1,3,4-butanetriol. We have shown that transamination, an important step for bespoke synthesis of small molecule medicines, is biologically realisable using enzymes with a broad substrate range, such as omega-transaminases, within living yeast cells that are fed low-cost substrates for bioconversion.