Fig. 4

Schematic representation of the proposed nucleotide sugar biosynthesis related to EPS production in K. baliensis. Starting with the phosphorylation of fructose to fructose-6-phosphate (6) or glucose to glucose-6-phosphate (1), these intermediates can be converted into mannose-6-phosphate (7) or glucose-1-phosphate (2), respectively. Mannose-6-phosphate can be further converted into mannose-1-phosphate (8) and finally into GDP-mannose. UGP (3) catalyzes the synthesis of UDP-glucose from glucose-1-phosphate. UDP-glucose can be further isomerized to UDP-galactose (4) or UDP-glucuronic acid (5). The proposed pathway for the biosynthesis of activated nucleotide sugar precursors is based on publications from Kornmann et al. [18] and Pühler et al. [26]. The corresponding genomic locations of these respective genes are listed in Additional file 2: Table S2: gk-gene coding for a Glucokinase (EC 2.7.1.2); 2: pgm-gene coding for a Phosphoglucomutase (EC 5.4.2.2); 3: ugp-gene coding for an UDP-glucose-1-phosphate uridylyltransferase (EC 2.7.7.9); 4: galE-gene coding for an UDP-glucose-4-epimerase (EC 5.1.3.2); 5: ugd-gene coding for an UDP-glucose dehydrogenase (EC 1.1.1.22); 6: fk-gene coding for a Fructokinase (EC 2.7.1.4); 7: mpi-gene coding for a Mannose-6-phosphate isomerase (EC 5.3.1.8); 8: pmm-gene coding for a Phosphomannomutase (EC 5.4.2.8); 9: mpg-gene coding for a Mannose-1-phosphate guanyltransferase (EC 2.7.7.22)