Abstract: The present invention relates to methods for producing a hyaluronic acid with a desired average molecular weight in the range of 20,000-800,000 Dalton, the methods comprising the steps of: (a) cultivating a recombinant Bacillus host cell at a first temperature conducive to its growth, wherein the Bacillus host cell comprises a nucleic acid construct comprising a hyaluronan synthase encoding sequence operably linked to a promoter sequence foreign to the hyaluronan synthase encoding sequence; (b) then cultivating the recombinant Bacillus host cell of step (a) at a second temperature higher than the first temperature of step (a) under conditions suitable for production of the hyaluronic acid, whereby the Bacillus host cell produces hyaluronic acid with a desired average molecular weight in the range of 20,000-800,000 Dalton; and (b) recovering the hyaluronic acid.

Abstract: A process for the production of a valuable compound, comprising the steps of a) fermentation of a filamentous bacterial or fungal strain (e.g. a Streptomyces strain or an Aspergillus strain) in a fermentation medium wherein a carbohydrate during fermentation is added in a cyclic pulse dosing/pause way, wherein the pulse dosing time is shorter than the pause time and b) recovery of the valuable compound from the fermentation broth.