Metabolic engineering for production of functional polysaccharides

[Display omitted] •Functional polysaccharides (FPs) have important industrial and pharmaceutical uses.•There is focus on metabolic engineering of microbial factories for FP production.•Many microbes have been explored for complex FP (e.g. levan, heparosan) production.•New enzymatic, analytical and regulatory tools will impact future successes. Functional carbohydrate polymers are of immense industrial interest for high value applications. Distinct biosynthetic pathways allow for metabolic engineering approaches for production in microbial cell factories. The most common strategies in recent years included the attenuation of central carbon metabolism, improved substrate utilization or enhanced intracellular sugar nucleotide precursor levels. Recombinant expression in more suitable surrogate host organisms has demonstrated remarkable results for the heterologous production of glycosaminoglycans. However, industrial application of pharmacological active functional polysaccharides is often limited by costly post-polymerization modifications and downstream processing. With increasing knowledge of bottleneck enzymes and fluxes, it will be possible to enable a sustainable microbial production of high value polysaccharides and tailor artificial polymers towards specific applications.