ELSEVIER FEMS Microbiology Letters I33 (I 995) I 19- I25 Metabolic studies by ‘H NMR of different forms of zyxwvutsrqponmlkjih Trypanosoma cru~i as obtained by ‘in vitro’ culture M. Sanchez-Moreno *, M.C Fernandez-Becerra, J.J. Castilla-Calvente, A. Osuna Institute ~f’Biorechn&gy. Group Biochemical und Molecular PamsitologJ, Faculp of Sciences. Unkersity qf Gmnada. Campus Unirersitario Fuentenuel,a s/n. E-18071 Granada. Spain Received IO July 1995; revised 4 September 1995; accepted 5 September 1995 Abstract By culturing Tty~anosomu cruzi epimastigotes in modified Grace’s medium with 10% foetal bovine serum, a significant quantity of metacyclic forms could be obtained. Transformation was observed after 8 days of culture, with metacyclic forms reaching 75%. Cultured Vero cells were infected with metacyclic forms and maintained until free-amastigote forms were obtained. Additionally, amastigote-like forms could be obtained by subjecting metacyclic cultures to heat shock. Parasites were grown with glucose as the major carbon source. The metabolites produced and excreted during culture were identified by difference proton nuclear magnetic resonance spectroscopy and quantified by enzymatic methods. The final products of glucose catabolism differed not only quantitatively but also qualitatively for the three major life-cycle stages of T. cruzi. The end products of metabolism produced by epimastigote forms were mainly acetate and pyruvate and, to a lesser extend, L-alanine and ethanol. Differences between epimastigotes and metacyclic forms were only quantitative. However, free amastigotes as well as amastigote-like forms, excreted acetate, glycerol, and pyruvate and to a lesser extent succinate, but no L-alanine or ethanol. Kewords: Tnppunosomu cruzi: Amastigote; Amastigote-like; In vitro culture; Metabolism 1. Introduction parasite forms [3,4]. The carbon skeleton of the Trypano~~ma cruzi has a complex life cycle, involving bloodstream trypomastigotes and the intra- cellular multiplicative stage, called amastigotes. In the intermediate host (haemotophagous insect), the epimastigote and metacyclic trypomastigote stages develop in the intestine and rectum [1,2]. Recent studies have confirmed that amino acids rather than glucose are the energy substrates preferred by these amino acids is broken down and metabolised via the tricarboxylic acid cycle [3,5]. It is well known that in addition to amino acids, all stages of the parasite’s life cycle actively catabolize glucose via the Emb- den-Meyerhof pathway, both under aerobic and anaerobic conditions and even in the presence of proteins and amino acids. Under these conditions, the cells produce a mixture of COZ and reduced end-products, such as mono- and dicarboxylic acids, which are mainly succinate, alanine and acetate [5-71. However, there is some controversy with respect to the end-products of glucose metabolism produced by * Corresponding author. Tel.: +34 (58) 24 32 63; Fax: +34 (58) 24 3 I 74; E-mail: msanchezm@ugr.es. 037X- 1097/95/$09.50 0 1995 Federation of European Microbiological Societies. All rights reserved SSDI 0378- 1097(95)00347-9 Downloaded from https://academic.oup.com/femsle/article-abstract/133/1-2/119/497073 by guest on 12 June 2020