Process for the production of hyaluronic acid in Escherichia coli or Bacillus subtilis

A process for the production of hyaluronic acid in Bacillus subtilis, wherein said process comprises:

• (a) culturing Bacillus subtilis cells transformed with a grac-lac system, in a medium under conditions suitable for producing hyaluronic acid, and in the presence of isopropyl-β-thiogalactopyranoside (IPTG) as an inducer, wherein said Bacillus subtilis cells are transformed with:
• (i) at least one episomal plasmid vector comprising a sequence coding for a hyaluronan synthase, and a sequence coding for a UDP-glucose dehydrogenase in tandem, under the control of a single strong inducible promoter Pgrac which uses the lac repressor, or
• (ii) at least one episomal plasmid vector comprising a sequence coding for a hyaluronan synthase, a sequence coding for a UDP-glucose dehydrogenase, a sequence coding for a UDP-glucose pyrophosphorylase and a sequence coding for a glucose 6 phosphate isomerase, under the control of a single strong inducible promoter Pgrac which uses the lac repressor;
• and
• (b) recovering hyaluronic acid from the culture medium;
• wherein said Bacillus subtilis cells transformed with the plasmid vector of (i) or (ii) are preselected on an IPTG gradient;
• and
• wherein hyaluronic acid having a weight average molecular weight in the range 100-500 KD is produced when the fermentation time is 80-160 hours;
• hyaluronic acid having a weight average molecular weight in the range 500-1000 KD is produced when the fermentation time is 40-80 hours;
• or hyaluronic acid having a weight average molecular weight in the range 1×106-2×106 D is produced when the fermentation time is 12-40 hours.