Biosynthesis of polyhydroxyalkanoates (PHAs) with continuous feeding of mixed organic acids as carbon sources by Ralstonia eutropha

Abstract

Feeding strategies of feeding mixed organic acids as carbon sources for the biosynthesis of polyhydroxyalkanoates (PHAs) by Ralstonia eutropha were investigated. A feeding strategy was proposed according to the singular optimization control theory after comparing several feeding strategies of mixed acids for PHAs formation which referred to that the culture was absent of carbon sources firstly, and mixed acids was fed throughout the procedure at varying rates, additionally, to keep the cell more active, nitrogen source (sulfate ammonia) was also fed from about the 12th hour of the fermentation. In contrast with the batch culture in which the maximum dry cell weight and PHAs concentration were only 3.89 and 1.45 g/l, the corresponding values of the continuous feeding fed-batch culture were increased to 14.35 and 6.89 g/l, respectively.