Abstract: A yeast comprising a nucleotide sequence expression system expressing a synthetic Calvin cycle comprising heterologous genes, which include at least a) a gene encoding an enzyme from the class of the ribulose-bisphosphate carboxylases (EC number: 4.1.1.39) (RuBisCO gene); and b) a gene encoding an enzyme from the class of the ribulose phosphate kinases (EC number: 2.7.1.19) (PRK gene), which is expressing; wherein the yeast optionally comprises a heterologous expression construct expressing a gene of interest (GOI) and/or wherein each of said RuBisCO gene and said PRK gene, is fused with a nucleotide sequence encoding a peroxisomal targeting signal (PTS).