title: Increased secretion of exopolysaccharide and virulence potential of a mucoid variant of Salmonella enterica serovar Montevideo under environmental stress.
abstract: During an investigation to increase the recovery of Salmonella enterica from Oregano, an increased expression of exopolysaccharide was induced in Salmonella serovar Montevideo. The atypical mucoid (SAL242S) and the non-mucoid (SAL242) strains of Montevideo were compared and characterized using various methods. Serotyping analysis demonstrated that both strains are the same serovar Montevideo. Electron microscopy (EM) of cultured SAL242S cells revealed the production of a prominent EPS-like structure enveloping aggregates of cells that are composed of cellulose. Mucoid cells possessed a higher binding affinity for Calcofluor than that of the non-mucoid strain. Genotypic analysis revealed no major genomic differences between these morphotypes, while expression analyses using a DNA microarray shows that the mucoid variant exhibited heightened expression of genes encoding proteins produced by the SPI-1 type III secretion system. This increased expression of SPI1 genes may play a role in protecting Salmonella from environmental stressors. Based on these observations, Salmonella serovar Montevideo mucoid variant under stressful or low-nutrient environments presented atypical growth patterns and phenotypic changes, as well as an upregulated expression of virulence factors. These findings are significant in the understanding of survival abilities of Salmonella in a various food matrices.
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States. Electronic address: junia.jean-gillesbeaubrun@fda.hhs.gov.
authors.forename: J
authors.initials: J
authors.lastname: Jean-Gilles Beaubrun
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States.
authors.forename: Ben D
authors.initials: BD
authors.lastname: Tall
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States; UMCP JIFSAN Program, 5201 Paint Branch Pkwy Patapsco Building Suite 2134, University of Maryland, College Park 20742, United States.
authors.forename: M-L
authors.initials: ML
authors.lastname: Flamer
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States.
authors.forename: I
authors.initials: I
authors.lastname: Patel
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States.
authors.forename: G
authors.initials: G
authors.lastname: Gopinath
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States; Frostburg State University, 101 Braddock Rd, Frostburg MD 21532, United States.
authors.forename: Winny
authors.initials: W
authors.lastname: Auguste
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States; Branch High School 14121 Old Columbia Pike, Burtonsville MD 20866, United States.
authors.forename: Catherine
authors.initials: C
authors.lastname: Jean
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States; Branch High School 14121 Old Columbia Pike, Burtonsville MD 20866, United States.
authors.forename: Melvin
authors.initials: M
authors.lastname: George
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States.
authors.forename: Carmen
authors.initials: C
authors.lastname: Tartera
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States.
authors.forename: L
authors.initials: L
authors.lastname: Ewing
authors.affiliation: U.S. Food and Drug Administration, Laurel, MD 20708, United States.
authors.forename: D E
authors.initials: DE
authors.lastname: Hanes
mesh_terms: D004777:Environment; D020869:Gene Expression Profiling; D005838:Genotype; D058889:Molecular Typing; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D019779:Salmonella enterica / Q000145:classification / Q000472:pathogenicity / Q000502:physiology* / Q000648:ultrastructure; D012703:Serotyping; D013312:Stress, Physiological; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D011135:Polysaccharides, Bacterial; D037521:Virulence Factors
keywords: Cellulose; Exopolysaccharide; Montevideo; Salmonella