ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Continuous production of citric acid from raw glycerol by Yarrowia lipolytica in cell recycle cultivation

Anita Rywińska and Waldemar Rymowicz

Department of Biotechnology and Food Microbiology, Faculty of Food Science, Wroclaw University of Environmental and Life Sciences, PL 50-375 Wroclaw, Poland

E-mail: Anita.Rywinska@wnoz.up.wroc.pl

Abstract: The kinetics of continuous citric acid (CA) fermentation, using two acetate-negative mutants of Yarrowia lipolytica (Wratislavia AWG7 and Wratislavia 1.31) with long-term cell recycle, were investigated at a dilution rate (D) of 0.011 h⁻¹. The capacity of the mutants to produce CA from raw glycerol under steady state conditions was compared. The process involving the Wratislavia AWG7 strain showed that this strain was a better producer of CA than the Wratislavia 1.31 strain in this regime. In steady state, the concentration of CA in the effluent was constant and amounted to 116 g dm⁻³. This corresponded to a volumetric CA production rate of 1.3 g dm⁻³ h⁻¹. A stable high-level production of CA was maintained for over 400 h of operation. The Wratislavia AWG7 strain employed remained highly stable throughout the experiment and demonstrated good viability, high genetic and phenotypic stability over the long-term continuous fermentation process.

Keywords: cell recycle – citric acid – raw glycerol – Yarrowia lipolytica

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-010-0093-8

Chemical Papers 65 (2) 119–123 (2011)