Received: 1 May, 2009. Accepted: 20 November, 2009. Original Research Paper Dynamic Biochemistry, Process Biotechnology and Molecular Biology ©2009 Global Science Books Agave spp. and Dasylirion sp. Fructans as a Potential Novel Source of Prebiotics Judith E. Urías-Silvas 1 • Mercedes G. López 2* 1 Desarrollo y Calidad de Productos Agroalimentarios, CIATEJ A.C., Av. Normalista 800, Colinas de la Normal, 44290, Guadalajara, Jalisco, Mexico 2 Departamento de Biotecnología y Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN, CINVESTAV-Irapuato, Km. 9.6 Libramiento Norte Carretera León-Irapuato, 36821. Irapuato, Guanajuato, Mexico Corresponding author: * mlopez@ira.cinvestav.mx ABSTRACT Prebiotics of the inulin-type fructans have been studied for many years under a wide range of conditions, including concentration, degree of polymerization and variety of probiotics. This work is the first that addresses the potential of Agave spp. and Dasylirion sp. fructans as prebiotics. Fructans from five different Agave species and from Dasylirion sp. grown in six different geographic areas were tested with six different bifidobacteria and four lactobacilli strains, with commercial inulin-type fructans used as positive controls. Results indicate that bifidobacteria and lactobacilli grew using species of Agave and Dasylirion fructans as a carbon source. Most fructans stimulated the growth of both genera more efficiently than commercial inulin, as indicated by the absorbance and pH values. Fructans of Dasylirion sp. from Chihuahua and Agave tequilana from Guanajuato were the most effective, followed by Raftilose ® Synergy1, a commercial inulin. This study supports previous reports that acetic, formic, and lactic acids were the main detected acids in all cases. This work further proves the potential of Agave and Dasylirion fructans as prebiotics. _____________________________________________________________________________________________________________ Keywords: agave, bifidobacteria, lactobacilli, prebiotic, SCFA Abbreviations: DP, degree of polymerization; HPLC, high performance liquid chromatography; MALDI-TOF-MS, matrix assisted laser desorption/ionization time-of-flight-mass spectrometry; SCFA, short chain fatty acids; TLC, thin layer chromatography INTRODUCTION Agave plants were and continue being of great importance in Mexico, supplying food, beverage, fiber and other re- sources. Mexico is the origin center, evolution, and diver- sification of this genus. Of the approximately 300 species described, 75% are found within Mexico (García-Mendoza and Galván 1995). The principal photosynthetic products of the CAM metabolism in agaves are fructans (Sánchez- Marroquín and Hope 1953). López et al. (2003) reported the molecular structure of fructans from A. tequilana Weber var. azul to be a complex mixture containing primarily (2- 1) and some (2-6) linkages, and are highly branched with terminal or internal glucose moieties, named graminans and agavins, respectively (Mancilla-Margalli and López 2006). Mancilla-Margalli and López (2006) reported structural differences of fructans between and within species of Agave, the latter grown in different environmental regions. The ob- served structural heterogeneity could be attributed to plant adaptation mechanisms allowing the plants to survive in inhospitable areas. In general, fructans are non-reducing oligosaccharides that are basically formed of linear or branched structures of fructosyl units with a terminal glucose moiety (Wang et al. 1999). Because of the -configuration of the anomeric C2 in their fructose monomers, fructans are resistant to hydro- lysis by human digestive enzymes (-glucosidase, maltase, isomaltase, and sucrase), which are specific for -glyco- sidic bonds. Fructans are thus classified as non-digestible oligosaccharides (Vijn and Smeekens 1999), reaching the large intestine essentially intact. They are also considered as a prebiotic (Wang and Gibson 1993; Gibson et al. 1995; Crittenden 1999) in that they serve as a substrate for the colonic bacteria. A prebiotic is an ingredient selectively fer- mented that affects specific changes on composition and/or activity of the gastrointestinal microflora, which confers benefits upon the host’s well-being and health (Gibson et al. 2004). The human intestinal microbial flora represents a rich ecosystem composed of a wide range of metabolically ac- tive microorganisms that play an important role in influen- cing the health of the host. In terms of health, of the several hundred species of bacteria that colonize the large intestine, the most significant organisms are the bifidobacteria (Gib- son and Roberfroid 1995). Bifidobacteria is the major com- ponent of the microbial barrier to infection, producing a range of antimicrobial agents that are active against Gram- positive and -negative organisms (Gibson and Wang 1994). Lactobacilli also contribute to good health in that they pro- duce a number of antimicrobial agents, but are present in much lower levels in the human colon (Rastall 2004). The presence and predominance of bifidobacteria is essential for the prevention of diseases and maintenance of good health (Mitsuoka 1990; Rastall 2004). Accordingly, considerable research is being directed towards promoting bifidobacteria growth in the large intestine. The fermentation of fructans in the colon generates short chain fatty acids (SCFA), lactic and formic acids, and gases including H 2 , CO 2 , and CH 4 as products of anaerobic metabolism (Roberfroid 1993, 2005). Fructan fermentation is an important process since it favors the maintenance and the development of bacterial flora, as well as the colonic epithelial cells (García-Peris et al. 2002; Gibson et al. 2005). The nutritional and biological properties of chicory inu- lin include dietary fiber effects, selective stimulation of bifi- dobacteria growth in the colon, preventing colon cancer, in- creasing mineral absorption, stimulation of the immunolo- gic system, and systemic modulation of lipid metabolism (Roberfroid et al. 1993, 1998; Roberfroid and Delzenne 1998; Roberfroid 2000). ®