UDC 663.12:57.083.13 scientific note ISSN 1330-9862 (FTB-1357) Differentiation Between Amino Acids Used as Carbon and Energy Sources During Growth of Geotrichum candidum Geo17 Lydia Adour 2 , Catherine Couriol 1 and Abdeltif Amrane 1 * 1 LARCIP/LPS, Université de Rennes 1, Campus de Beaulieu, Bât. 10 A, CS 74205, Avenue du Général Leclerc, FR-35042 Rennes Cedex, France 2 Laboratoire de Chimie Appliquée et de Génie Chimique, Université Mouloud Mammeri, Hasnaoua 1, Tizi-Ouzou, Algérie Received: July 27, 2004 Revised version: November 8, 2004 Accepted: November 22, 2004 Summary Geotrichum candidum Geo17 was cultivated on peptones as carbon and nitrogen source, and in the presence of lactate as the second carbon source. From the analysis of the initial and final culture medium after total hydrolysis, the yield of consumption was determined for each amino acid. Amino acids have been considered a convenient carbon source for biosynthesis, while the rest of the amino acids were assumed to be used only as a nitrogen source, with the corresponding carbon released as CO 2 resulting from energy supply. Car- bon mass balances confirmed this assumption. A clear differentiation between the amino acids assimilated as carbon sources and those assimilated as energy sources was therefore highlighted. Key words: amino acids, carbon and nitrogen sources, Geotrichum candidum, growth Introduction The yeast Geotrichum candidum is involved in the neutralization of the curd during the ripening of Cam- embert cheese (1). This step plays an important role in the development of texture (2) and the further growth of surface bacterial populations (3). Curd neutralization re- sults from both lactic acid assimilation (4) and ammonia release due to the deamination of amino acids (5). Meta- bolization of carbon and nitrogen substrates appears therefore as a key-factor in the ripening process, espe- cially that related to the assimilation of amino acids. In order to investigate the nutritional mechanisms involved in the assimilation of carbon and nitrogen sour- ces by G. candidum, submerged cultures of the fungi have been carried out (6). Lactate as a carbon source and pep- tones as a carbon and nitrogen source have been used to simulate the aqueous phase of Camembert cheese (7). Peptones are a complex mixture of various peptides. The amino acids constitutive of these peptides may be assimilated not only as nitrogen sources (for the main part of them), but also as carbon sources, as previously shown (8). Only general information may be deduced from the total amount of peptones assimilated (6); iden- tification of the amino acids assimilated during culture of G. candidum (analysis of the culture medium after to- tal amino acid hydrolysis) may be more informative. The differentiation between the amino acids which are convenient carbon sources and those assimilated only as nitrogen sources was also examined in this paper. 85 L. ADOUR et al.: Cultivation of Geotrichum candidum, Food Technol. Biotechnol. 43 (1) 85–89 (2005) * Corresponding author; Fax: ++33 2 23 23 57 65; E-mail: abdeltif.amrane@univ-rennes1.fr