Biochemical Engineering Journal 37 (2007) 177–183 Study of levan production by Zymomonas mobilis using regional low-cost carbohydrate sources Marcos Roberto de Oliveira a , Rui S´ ergio Santos Ferreira da Silva b , Jo˜ ao Batista Buzato a , Maria Antonia Pedrine Colabone Celligoi a,∗ a Department of Biochemistry and Biotechnology, Londrina State University, Post-Box 6001, 86051-990 Londrina, Paran´ a, Brazil b Department of Food Technology, Londrina State University, Post-Box 6001, 86051-990 Londrina, Paran´ a, Brazil Received 13 April 2006; received in revised form 23 April 2007; accepted 25 April 2007 Abstract The use of alternative regional low-cost substrates has become very interesting because in addition to the ease of acquisition it presents a relatively low cost. In this study using statistical instruments, the exopolysaccharide levan production by the Zymomonas mobilis microorganism was analyzed varying the carbon source (commercial sucrose, molasses and sugar cane syrups) and the fermentation medium constituents. There was a decrease in levan production in the molasses medium (2.533 g L -1 ) when compared to the commercial sucrose (21.685 g L -1 ) and syrup (15.456 g L -1 ) media. Yeast extract and KH 2 PO 4 were significant in the commercial sucrose medium for levan production and in the syrup medium the yeast extract and MgSO 4 were significant. Although sugar cane syrup up produced about 28.724% less levan compared to commercial sucrose, biomass production in the syrup was 2.76 times greater than in commercial sucrose (0.857 and 2.366 g L -1 ) that could justify joint levan and Z. mobilis ATCC 31821 biomass production. Studies are needed on the use of alternative substrates and complexes in biotechnology to assess the composition of these media, avoiding unnecessary supplementation with vitamins and minerals salts, when using the formulations of the mediums defined for the complex mediums. © 2007 Elsevier B.V. All rights reserved. Keywords: Zymomonas mobilis; Levan; Molasses sugar cane; Sugar cane syrups 1. Introduction The levan is exopolysaccharide that have a wide variety of applications. The levan can be used in medicine as a hypo-cholesterol [1], antitumor [2], immune modulator [3], anti- inflammatory [4] and plasma substitute [5] agent. It is used in foods as a source of di-fructofuranoses [6], fructose and fruc- tooligosaccharides [7] and as an emulsifying and encapsulating agent, color and flavor vehicle [8] and fat substitute [9]. The Z. mobilis ATCC 31821 bacterium is considered a poten- tial candidate for large scale levan production [10]. It is produced from the catalyzed transfructolization reaction by the levansu- crase enzyme (-2,6 frutan: d-glucose-fructosyltransferase, EC. 2.4.1.10) that uses sucrose as substrate. Levan can be produced as ∗ Corresponding author. Tel.: +55 43 3371 4270; fax: +55 43 3371 4054. E-mail address: macelligoi@uel.br (M.A.P.C. Celligoi). economically valuable sub-products in alcohol distilleries using sucrose as substrate [11]. Sugar cane syrup and sugar cane molasses are complex sub- strates with a high concentration of sucrose and a great variety of salts that are necessary for metabolite production of indus- trial interest. The sugar cane molasses is noted for its sugar content and sugars usually contribute 60–65% of the solids in sugarcane molasses. Sucrose usually comprises 65–70% of the total sugars with glucose and fructose contributing the highest proportion of the other sugars in molasses. Other carbohydrates usually comprise 10–16% of the solids with pectin compounds and reaction products present in significant quantities. Non- nitrogenous acids contribute 4–9% of the solids with aconitic acid present in significant quantities. Protein and amino acids usually represent only 1–2% of molasses solids. Minerals con- tribute most (8–17%) of the other solids in molasses. Sugarcane molasses has high concentrations of calcium (1.0–1.1%), mag- nesium (0.4–0.5%) potassium (3–4%), chlorine (2–3%), and 1369-703X/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.bej.2007.04.009