Mut- methylotrophic yeast

A recombinant methanol utilization pathway deficient methylotrophic yeast (Mut−) host cell which is engineered:

• a) by one or more genetic modifications to reduce expression of a first and a second endogenous gene compared to the host cell prior to said one or more genetic modifications, wherein
• i. the first endogenous gene encodes alcohol oxidase 1 (Aox1) comprising the amino acid sequence identified as SEQ ID NO:1 or a homologue thereof, and
• ii. the second endogenous gene encodes alcohol oxidase 2 (Aox2) comprising the amino acid sequence identified as SEQ ID NO:3 or a homologue thereof,
• and
• b) by one or more genetic modifications that increases expression of an alcohol dehydrogenase 2 (Adh2) gene compared to the host cell prior to said one or more genetic modifications, wherein the Adh2 gene encodes an alcohol dehydrogenase 2 (ADH2), and wherein the methylotrophic yeast is a P. pastoris strain.