Exopolysaccharide yield as a kinetic parameter for the statistical optimization of EPS production by Klebsiella pneumoniae

Abstract

A Klebsiella pneumoniae strain isolated form a chronically infected patient with urinary tract infection produces an extracellular polysaccharide giving the strain a highly mucoid appearance. Growth characteristics and exopolysaccharide production of this strain was investigated in culture with synthetic medium. For the ultimate aim of optimizing the exopolysaccharide productivity together with the EPS yield (g/gbiomass) the application of Plackett-Burman statistical experimental design gave conflicting results for ammonium sulphate as the main effect. Moreover, in pH-controlled bioreactor EPS production was not associated with the growth and was maximized at lower growth rate. Furthermore, this study showed that for maximization of EPS production together with EPS yield, ammonium limited fed batch culture in oxygenated bioreactor is the method of choice to be used. Applying this procedure, an increase in the maximum dry weight of cells. EPS yield and EPS concentration (90 fold increase) was obtained compared to a classical batch culture. © 2008 Asian Network for Scientific Information.