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The Scientific World Journal
Volume 2012, Article ID 907143, 5 pages
Research Article

Animal Bones Char Solubilization by Gel-Entrapped Yarrowia lipolytica on Glycerol-Based Media

1Department of Chemical Engineering, Faculty of Sciences, University of Granada, c/Fuentenueva s/n, 18071 Granada, Spain
2Faculty of Agricultural and Environmental Sciences, University of Rostock, 18051 Rostock, Germany
3Institute of Biotechnology, University of Granada, c/Fuentenueva s/n, 18071 Granada, Spain

Received 11 October 2011; Accepted 21 December 2011

Academic Editors: P. F. Christakopoulos and A. Roldán Garrigós

Copyright © 2012 Maria Vassileva et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Citric acid was produced with free and k-carrageenan-entrapped cells of the yeast Yarrowia lipolytica in single and repeated batch-shake-flask fermentations on glycerol-based media. Simultaneous solubilization of hydroxyapatite of animal bone origin (HABO) was tested in all experiments. The highest citric acid production by free yeast cells of 20.4 g/L and 18.7 g/L was reached after 96 h of fermentation in the absence and presence of 3 g/L HABO, respectively. The maximum values for the same parameter achieved by gel-entrapped cells in conditions of single batch and repeated-batch fermentation processes were 18.7 g/L and 28.1 g/L registered after 96 h and the 3d batch cycle, respectively. The highest citric acid productivity of 0.58 g L−1 h−1 was obtained with immobilized cells in repeated batch mode of fermentation when the added hydroxyapatite of 3 g/L was solubilized to 399 mg/L whereas the maximum efficiency of 89.0% was obtained with 1 g/L of HABO.