Fig. 1

The relationship between alginate biosynthesis and the cellular metabolism in P. fluorescens. a The proteins and metabolites needed for alginate biosynthesis. b A simplified model of the cell’s metabolism highlighting the processes identified in the present study as being important for full alginate biosynthesis levels. The genes discussed in the paper are highlighted in yellow. The Entner-Doudoroff pathway and the oxidative part of the pentose phosphate pathway are indicated by red arrows, and the non-oxidative part of the pentose phosphate pathway with purple arrows. Green arrows indicate other pathways competing with accumulation of the three metabolites Fru6P, GTP and c-di-GMP, while blue arrows indicate pathways that would increase the synthesis of one of these three metabolites. Each arrow may represent several enzymatic steps. Abbreviations: OM: Outer membrane, IM: Inner membrane, M: mannuronic acid residue, G: guluronic acid residue, Ac: Acetyl, TCA: Tricarboxylic acid cycle, PP: the non-oxidative part of the pentose phosphate pathway, GN6P: Glucosamine 6-phosphate, PG: Peptidoglycan, G6P: Glucose 6-phosphate, 6PG: 6-phosphogluconate, Pyr: Pyruvate, ILV: Isoleucine Leucine Valine, B5: Pantothenate, Trp: Tryptophan, PRPP: Phosphoribosyl pyrophosphate, R5P: Ribose 5-phosphate, E4P: Erythrose 4-phosphate