ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
Effect of operating conditions on biomass growth during citric acid production by solid-state fermentation
Institute of Chemistry and Food Technology, Department of Agricultural and Food Wastes Bioutilization, University of Economics, ul. Komandorska 118/120, 53-345 Wroclaw, Poland
Received: 27 March 2007 Revised: 30 July 2007 Accepted: 13 September 2007
Abstract: The effect of aeration, agitation, and bed loading on biomass and product concentration during citric acid biosynthesis by
solid-state fermentation was investigated. For this purpose, Aspergillus niger S was cultivated on sugar beet pulp in a 4.5 dm3 horizontal rotating drum bioreactor. The results suggest that the parameters examined have a remarkable effect on the quantity
of biomass being formed and on the product concentration. The maximum citric acid production (about 150 g per kg of the substrate
dry matter) was obtained under the following conditions: aeration rate 0.2 dm3 kg−1 min−1, mixing (periodical) 1 min once an hour, and bed loading 30 % of the bioreactor working volume. However, these values did
not favour biomass formation. Moreover, it was found that accumulation of the product reached its maximum when the amount
of biomass was minimal (approximately 252-29 g per kg of the substrate dry matter) under the conditions involved.
Keywords: biomass assessment - solid-state fermentation - citric acid -
Full paper is available at www.springerlink.com.
Chemical Papers 62 (2) 141–146 (2008)