title: Phage-resistance linked to cell heterogeneity in the commercial strain Lactobacillus delbrueckii subsp. lactis Ab1.
abstract: The aim of this work was to study the relationship between the cell morphological heterogeneity and the phage-resistance in the commercial strain Lactobacillus delbrueckii subsp. lactis Ab1. Two morphological variants (named C and T) were isolated from this strain. Phage-resistant derivatives were isolated from them and the percentage of occurrence of confirmed phage-resistant cells was 0.001% of the total cellular population. Within these phage-resistant cell derivatives there were T (3 out of 4 total isolates) and C (1 out of 4 total isolates) variants. The study of some technological properties (e.g. proteolytic and acidifying activities) demonstrated that most of phage-resistant derivatives were not as good as the parental strain. However, for one derivative (a T variant), the technological properties were better than those of the parental strain. On the other hand, it was possible to determinate that the system of phage-resistance in the T variants was interference in adsorption step, with adsorption rates <15%. For the C variant derivative it was possible to demonstrate the presence of a restriction/modification system and, moreover, to determinate that this system could be Type I R/M.
authors.affiliation: Instituto de Lactología Industrial (Universidad Nacional del Litoral - CONICET), Santiago del Estero 2829, S3000AOM Santa Fe, Argentina. vivisuar@fiq.unl.edu.ar
authors.forename: Viviana B
authors.initials: VB
authors.lastname: Suárez
authors.forename: Natalia
authors.initials: N
authors.lastname: Maciel
authors.forename: Daniela
authors.initials: D
authors.lastname: Guglielmotti
authors.forename: Miriam
authors.initials: M
authors.lastname: Zago
authors.forename: Giorgio
authors.initials: G
authors.lastname: Giraffa
authors.forename: Jorge
authors.initials: J
authors.lastname: Reinheimer
mesh_terms: D000327:Adsorption; D001435:Bacteriophages; D004269:DNA, Bacterial / Q000032:analysis*; D004305:Dose-Response Relationship, Drug; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D005838:Genotype; D006801:Humans; D048668:Lactobacillus delbrueckii / Q000145:classification / Q000235:genetics*; D008826:Microbial Sensitivity Tests / Q000379:methods; D009154:Mutation; D010641:Phenotype; D019105:Random Amplified Polymorphic DNA Technique / Q000379:methods; D013045:Species Specificity
chemical_list: D004269:DNA, Bacterial