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Appl Environ Microbiol

Title:		The blp Locus of Streptococcus pneumoniae Plays a Limited Role in the Selection of Strains That Can Cocolonize the Human Nasopharynx
Author(s):		Valente C; Dawid S; Pinto FR; Hinds J; Simoes AS; Gould KA; Mendes LA; de Lencastre H; Sa-Leao R;
Address:		"Laboratory of Molecular Microbiology of Human Pathogens, Instituto de Tecnologia Quimica e Biologica Antonio Xavier, Universidade Nova de Lisboa, Oeiras, Portugal. Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, USA Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA. BioISI-Biosystems & Integrative Sciences Institute, Faculdade de Ciencias da Universidade de Lisboa, Lisbon, Portugal. Institute for Infection and Immunity, St. George's, University of London, London, United Kingdom BUGS Bioscience, London Bioscience Innovation Centre, London, United Kingdom. Laboratory of Molecular Genetics, Instituto de Tecnologia Quimica e Biologica Antonio Xavier, Universidade Nova de Lisboa, Oeiras, Portugal Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, New York, USA. Laboratory of Molecular Microbiology of Human Pathogens, Instituto de Tecnologia Quimica e Biologica Antonio Xavier, Universidade Nova de Lisboa, Oeiras, Portugal rsaleao@itqb.unl.pt"
Journal Title:		Appl Environ Microbiol
Year:		2016
Volume:		20160815
Issue:		17
Page Number:		5206 - 5215
DOI:		10.1128/AEM.01048-16
ISSN/ISBN:		1098-5336 (Electronic) 0099-2240 (Print) 0099-2240 (Linking)
Abstract:		"Nasopharyngeal colonization is important for Streptococcus pneumoniae evolution, providing the opportunity for horizontal gene transfer when multiple strains co-occur. Although colonization with more than one strain of pneumococcus is common, the factors that influence the ability of strains to coexist are not known. A highly variable blp (bacteriocin-like peptide) locus has been identified in all sequenced strains of S. pneumoniae This locus controls the regulation and secretion of bacteriocins, small peptides that target other bacteria. In this study, we analyzed a series of cocolonizing isolates to evaluate the impact of the blp locus on human colonization to determine whether competitive phenotypes of bacteriocin secretion restrict cocolonization. We identified a collection of 135 nasopharyngeal samples cocolonized with two or more strains, totaling 285 isolates. The blp locus of all strains was characterized genetically with regard to pheromone type, bacteriocin/immunity content, and potential for locus functionality. Inhibitory phenotypes of bacteriocin secretion and locus activity were assessed through overlay assays. Isolates from single colonizations (n = 298) were characterized for comparison. Cocolonizing strains had a high diversity of blp cassettes; approximately one-third displayed an inhibitory phenotype in vitro Despite in vitro evidence of competition, pneumococci cocolonized the subjects independently of blp pheromone type (P = 0.577), bacteriocin/immunity content, blp locus activity (P = 0.798), and inhibitory phenotype (P = 0.716). In addition, no significant differences were observed when single and cocolonizing strains were compared. Despite clear evidence of blp-mediated competition in experimental models, the results of our study suggest that the blp locus plays a limited role in restricting pneumococcal cocolonization in humans. IMPORTANCE: Nasopharyngeal colonization with Streptococcus pneumoniae (pneumococcus) is important for pneumococcal evolution, as the nasopharynx represents the major site for horizontal gene transfer when multiple strains co-occur, a phenomenon known as cocolonization. Understanding how pneumococcal strains interact within the competitive environment of the nasopharynx is of chief importance in the context of pneumococcal ecology. In this study, we used an unbiased collection of naturally co-occurring pneumococcal strains and showed that a biological process frequently used by bacteria for competition-bacteriocin production-is not decisive in the coexistence of pneumococci in the host, in contrast to what has been shown in experimental models"
Keywords:		"Bacterial Proteins/genetics/*metabolism Gene Expression Regulation, Bacterial Humans Nasopharynx/*microbiology Pneumococcal Infections/*microbiology Streptococcus pneumoniae/genetics/*growth & development/isolation & purification/*metabolism;"
Notes:		"MedlineValente, Carina Dawid, Suzanne Pinto, Francisco R Hinds, Jason Simoes, Alexandra S Gould, Katherine A Mendes, Luis A de Lencastre, Herminia Sa-Leao, Raquel eng R01 AI101285/AI/NIAID NIH HHS/ Research Support, Non-U.S. Gov't 2016/06/19 Appl Environ Microbiol. 2016 Aug 15; 82(17):5206-15. doi: 10.1128/AEM.01048-16. Print 2016 Sep 1"