Advance Journal of Food Science and Technology 4(1): 46-50, 2012 ISSN: 2042-4876 © Maxwell Scientific Organization, 2012 Submitted: December 20, 2011 Accepted: January 21, 2011 Published: February 15, 2012 Corresponding Author: Adriana C. Flores-Gallegos, Food Research Department, School of Chemistry. Universidad Autonoma de Coahuila. Boulevard Venustiano Carranza and Jose Cardenas s/n. Republica Oriente. C.P. 25280, Saltillo, Coahuila, México 46 Inulinase Production by a Mexican Semi-Desert Xerophylic Penicillium citrinum Strain under Submerged Culture Adriana C. Flores-Gallegos, Jesús Morlett-Chávez, Cristóbal N. Aguilar and Raúl Rodríguez-Herrera Food Research Department, School of Chemistry, Universidad Autonoma de Coahuila, Boulevard Venustiano Carranza and Jose Cardenas s/n, Republica Oriente, C.P. 25280, Saltillo, Coahuila, México Abstract: The aim of the study was to produce inulinase under submerged culture (SmC) by a xerophylic fungal strain isolated from the Mexican semi-dessert and to verify its potential as an industrial inulinase producer. This enzyme can be obtained from microorganisms that live in close association with inulin plant store tissues. Inulin is a widespread plant polyfructan that serves as a storage polysaccharide in several plants and its depolymerization involves the action of inulinase. Inulinases are classified among hydrolases and target on the $-(2,1)-linkage of inulin which is hydrolyzed into fructose and glucose. These carbohydrates are promising candidates to be used as food ingredients and in production of fermenting sugars. However, their utilization is limited due to the high cost of their production thus it is necessary to find new inulinase producer strains with high productivity and desirable characteristics for industrial production. In the present study, Penicillium citrinum ESS produced extracellular inulinase with the highest enzymatic activity (18.7 U/L) at 48 h, 30°C and 25 rpm, respectively. Moreover, the medium that we propose for inulinase production has a simpler chemical composition than other reported in previous works. Even further improvements on the process are needed, within the experimental limits of this study, it was possible to demonstrate that the xerophylic fungal strain Penicillium citrinum ESS isolated from Mexican semi-dessert could compete favorably with other fungal strains reported in literature to produce inulinase industrially. Key words: Inulin, inulinase, Mexican semi-dessert, Penicillium citrinum ESS, submerged culture, xerophylic INTRODUCTION Inulin is a widespread plant polyfructan that has linear chains of $-(2,1)-linked fructose residues attached to a terminal sucrose residue (Edelman and Jefford, 1964). This polyfructan serves as a storage polysaccharide in the Compositae and Gramineae families, and is accumulated in the underground parts of several plants of Asteracea, including rusby (Vernoniaherbacea), Jerusalem artichoke (Helianthus tuberosus) and chicory (Cichoriumendivia) (Vandamme and Derycke, 1983). It has been previously described that organisms living in close association with plant tissues could be inulin degraders through enzymatic hydrolysis (Ohta et al., 2004; Hyde and Soytong, 2008). This process involves the action of inulinases, which are classified among the hydrolases and target on the $-(2,1)-linkage of inulin and hydrolyze it into fructose and glucose. The general reaction mainly involves action of two enzymes: exo- and endoinulinase (Chi et al., 2009) and potential biotechnological applications to these enzymes have been noticed (Ohta et al., 1993). These enzymes have been isolated from different microorganisms including Penicillium (Onodera and Shiomi, 1992; Balayan et al., 1996; Pessoni et al., 1999), Kluyveromyces (Gupta et al., 1994) and Aspergillus (Ettalibi and Baratti, 1990; Arand et al., 2002). In recent years, our group reported xerophilic fungal strains isolated from the Mexican semi-desert which have demonstrated to present very efficient enzymatic machinery (Cruz- Hernandez et al., 2005, 2006). These fungal strains have been studied due to their tolerance to extreme conditions typical from the region (long drough periods, high midday temperatures, and low night temperature, high osmotic pressures). The aim of this research was to study inulinase production by a fungal strain isolated from Mexican semi- desert and to verify its potential as an industrial inulinase producer. MATERIALS AND METHODS Microorganism: PenicilliumcitrinumESS was isolated from the Mexican semi-desert region (Cruz-Hernandez et al., 2005). Strain spores were propagated, harvested in