Finally, the route where β-alanine is converted into malonic semialdehyde either by the action of β-alanine-pyruvate aminotransferase (BAPAT) or γ-aminobutyrate transaminase (GABT) has been reported in E. coli ( Liao et al., 2007) and yeast ( Jessen et al., 2012) respectively ( Fig. 1a). Malonic semialdehyde is further reduced into 3HP by the action of 3-hydroxypropionate dehydrogenase or 3-hydroxyisobutyrate dehydrogenase. β-alanine is a precursor for the biosynthesis of pantothenic acid (vitamin B5), which by itself is a component of coenzyme A and acyl carrier protein, co-factors required by a large number of enzymes. In bacteria, β-alanine is produced via decarboxylation of l-aspartate by aspartate-1-decarboxylase encoded by gene panD. No ortholog of panD was found in the genome of S. cerevisiae and it was shown that the only active route for β-alanine biosynthesis was via spermine