Pathways involved in glyoxylate metabolism. Three pathways generate glyoxylate: glycolate metabolism, acetate metabolism and purine degradation. Glyoxylate enters the central metabolism through two pathways: direct conversion to malate by malate synthase G (GlcB) and/or malate synthase A (AceB) or conversion to 3-phosphoglycerate by glyoxylate carboligase (Gcl), tartronate semialdehyde reductase (GlxR) and glycerate kinase (GlxK). Genes with blue backgrounds were upregulated in ZG2 (icdANAD) and ZG3 (icdANADPΔudhA). ACO, aconitase; AllB, allantoinase; AllC, allantoate amidohydrolase; AllA, ureidoglycolate hydrolase; CS, citrate synthase; FUM, fumarase; Gcl, glyoxylate carboligase; GlxK, glycerate kinase; GlxR, tartronic semialdehyde reductase; ICL, Isocitrate lyase; KDH, α-Ketoglutarate dehydrogenase; MDH, malate dehydrogenase; SCS, Succinyl-CoA synthetase; SDH, succinate dehydrogenase.