title: Screening and characterization of extracellular polysaccharides produced by Leuconostoc kimchii isolated from traditional fermented pulque beverage.
abstract: We report the screening and characterization of EPS produced by LAB identified as Leuconostoc kimchii isolated from pulque, a traditional Mexican fermented, non-distilled alcoholic beverage produced by the fermentation of the sap extracted from several (Agave) maguey species. EPS-producing LAB constitutes an abundant bacterial group relative to total LAB present in sap and during fermentation, however, only two EPS-producing colony phenotypes (EPSA and EPSB, respectively) were detected and isolated concluding that despite the high number of polymer-producing LAB their phenotypic diversity is low. Scanning electron microcopy analysis during EPS-producing conditions revealed that both types of EPS form a uniform porous structure surrounding the bacterial cells. The structural characterization of the soluble and cell-associated EPS fractions of each polymer by enzymatic and acid hydrolysis, as by 1D- and 2D-NMR, showed that polymers produced by the soluble and cell-associated fractions of EPSA strain are dextrans consisting of a linear backbone of linked α-(1→6) Glcp in the main chain with α-(1→2) and α-(1→3)-linked branches. The polymer produced by the soluble fraction of EPSB strain was identified as a class 1 dextran with a linear backbone containing consecutive α-(1→6)-linked D-glucopyranosyl units with few α-(1→3)-linked branches, whereas the cell-associated EPS is a polymer mixture consisting of a levan composed of linear chains of (2→6)-linked β-D-fructofuranosyl residues with β-(2→6) connections, and a class 1 dextran. According to our knowledge this is the first report of dextrans and a levan including their structural characterization produced by L. kimchii isolated from a traditional fermented source.
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Av. Universidad 2001. Col. Chamilpa, Cuernavaca Morelos, 62210 México.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Torres-Rodríguez
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Av. Universidad 2001. Col. Chamilpa, Cuernavaca Morelos, 62210 México.
authors.forename: María Elena
authors.initials: ME
authors.lastname: Rodríguez-Alegría
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Av. Universidad 2001. Col. Chamilpa, Cuernavaca Morelos, 62210 México.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Miranda-Molina
authors.affiliation: Departamento de Biología, Facultad de Química, UNAM. Ciudad Universitaria, México D. F, Coyoacán, 04510 México.
authors.forename: Martha
authors.initials: M
authors.lastname: Giles-Gómez
authors.affiliation: Departamento de Biología, Facultad de Química, UNAM. Ciudad Universitaria, México D. F, Coyoacán, 04510 México.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Conca Morales
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Av. Universidad 2001. Col. Chamilpa, Cuernavaca Morelos, 62210 México.
authors.forename: Agustín
authors.initials: A
authors.lastname: López-Munguía
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Av. Universidad 2001. Col. Chamilpa, Cuernavaca Morelos, 62210 México.
authors.forename: Francisco
authors.initials: F
authors.lastname: Bolívar
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Av. Universidad 2001. Col. Chamilpa, Cuernavaca Morelos, 62210 México.
authors.forename: Adelfo
authors.initials: A
authors.lastname: Escalante
keywords: Dextran; Exopolysaccharides; Lactic acid bacteria; Leuconostoc kimchii; Levan; Pulque