title: Isolation and partial characterization of halotolerant lactic acid bacteria from two Mexican cheeses.
abstract: Isolated strains of halotolerant or halophilic lactic acid bacteria (HALAB) from Cotija and doble crema cheeses were identified and partially characterized by phenotypic and genotypic methods, and their technological abilities were studied in order to test their potential use as dairy starter components. Humidity, a(w), pH, and salt concentration of cheeses were determined. Genotypic diversity was evaluated by randomly amplified polymorphic DNA-polymerase chain reaction. Molecular identification and phylogenetic reconstructions based on 16S rRNA gene sequences were performed. Additional technological abilities such as salt tolerance, acidifying, and proteolytic and lipolytic activities were also investigated. The differences among strains reflected the biodiversity of HALAB in both types of cheeses. Lactobacillus acidipiscis, Tetragenococcus halophilus, Weissella thailandensis, and Lactobacillus pentosus from Cotija cheese, and L. acidipiscis, Enterococcus faecium, Lactobacillus plantarum, Lactobacillus farciminis, and Lactobacillus rhamnosus from doble crema cheese were identified based on 16S rRNA. Quantitative and qualitative assessments showed strains of T. halophilus and L. plantarum to be proteolytic, along with E. faecium, L. farciminis, and L. pentosus to a lesser extent. Lipolytic activity could be demonstrated in strains of E. faecium, L. pentosus, L. plantarum, and T. halophilus. Strains belonging to the species L. pentosus, L. plantarum, and E. faecium were able to acidify the milk media. This study evidences the presence of HALAB that may play a role in the ripening of cheeses.
authors.affiliation: Departamento de Graduados e Investigación en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Carpio y Plan de Ayala, CP 11340, Mexico City, Mexico.
authors.forename: Fredy
authors.initials: F
authors.lastname: Morales
authors.forename: Jesús I
authors.initials: JI
authors.lastname: Morales
authors.forename: César H
authors.initials: CH
authors.lastname: Hernández
authors.forename: Humberto
authors.initials: H
authors.lastname: Hernández-Sánchez
mesh_terms: D002611:Cheese / Q000032:analysis / Q000382:microbiology*; D019344:Lactic Acid / Q000378:metabolism*; D007777:Lactobacillaceae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D008800:Mexico; D008969:Molecular Sequence Data; D010802:Phylogeny; D012965:Sodium Chloride / Q000378:metabolism*
chemical_list: D019344:Lactic Acid; D012965:Sodium Chloride