Evaluation of () for Hyaluronic Acid Production.

Hyaluronic acid (HA) is a biopolymer formed by UDP-glucuronic acid and UDP-N-acetyl-glucosamine disaccharide units linked by β-1,4 and β-1,3 glycosidic bonds. It is widely employed in medical and cosmetic procedures. HA is synthesized by hyaluronan synthase (HAS), which catalyzes the precursors' ligation in the cytosol, elongates the polymer chain, and exports it to the extracellular space. Here, we engineer () for HA production by inserting the genes encoding UDP-glucose 6-dehydrogenase, for UDP-glucuronic acid production, and HAS. Two microbial HAS, from () and (), were evaluated separately. Additionally, we assessed a genetic switch using integrases in to uncouple HA production from growth. Four strains were constructed containing both genes under the control of different promoters. In the strain containing the genetic switch, HA production was verified by a capsule-like layer around the cells by scanning electron microscopy in the first 24 h of cultivation. For the other strains, the HA was quantified only after 48 h and in an optimized medium, indicating that HA production in is limited by cultivation conditions. Nevertheless, these results provide a proof-of-principle that is a suitable host for HA production.