RESUMO
Cronobacter spp. are opportunistic pathogenic bacteria responsible for severe infections in neonates. Powdered infant formula has been confirmed to be the source of infection in some cases. Bacteriophages offer a safe means for eliminating this pathogen. In the present study, we characterized two closely related Cronobacter-specific bacteriophages of the proposed genus "GAP227virus". The phages Dev-CD-23823 and Dev-CT57 possessed broad host specificity, as they infected 88% and 80% of the Cronobacter strains tested. Genome sequence comparisons of phages Dev-CD-23823 and Dev-CT57 showed different levels of similarity to the prototype GAP227 phage. The Dev-CT57 phage was highly similar, whereas the Dev-CD-23823 phage showed only 75% sequence identity. A phylogenic tree based on the RNA polymerase (RNAP) gene from selected representatives of the subfamily Autographivirinae confirmed the grouping of Dev-CD-23823, Dev-CT57 and GAP227 in one cluster together with phages PP2, Phi80-18 and PhiR8-01. A common conserved motif was also detected in the RNAP promoters of these phages. The functional activity of these RNAP promoters was confirmed experimentally using a promoter probe vector, and a phage-specific signal was observed; however, some cross-specificity of Dev-CD-23823 and Dev-CT57 promoters was also detected. These results will contribute to our understanding of the biology and evolution of Autographivirinae phages.
Assuntos
Cronobacter/virologia , RNA Polimerases Dirigidas por DNA/genética , Podoviridae/classificação , Podoviridae/genética , Ligação Viral , Sequência de Bases , Cronobacter/isolamento & purificação , Genoma Viral/genética , Especificidade de Hospedeiro , Humanos , Alimentos Infantis/microbiologia , Recém-Nascido , Filogenia , Podoviridae/isolamento & purificação , Regiões Promotoras Genéticas/genéticaRESUMO
A newly identified lytic Cronobacter phage, GW1, was isolated from the Pearl River of Guangzhou, China. GW1 had a double-stranded DNA genome of 39,695 nucleotides with an average GC content of 53.18 %. Among the 49 open reading frames (ORFs) identified, genes for rRNA, tRNA, antibiotic resistance, and virulence factors were not found in the phage genome. The morphology, genomic features, and phylogenetic position of GW1 revealed that it represents a new species in the genus T7virus. This novel lytic Cronobacter phage may provide an alternative for phage therapy and biocontrol against Cronobacter.
Assuntos
Bacteriófagos/genética , Cronobacter/virologia , Genoma Viral , Podoviridae/genética , Bacteriófagos/classificação , Bacteriófagos/isolamento & purificação , Composição de Bases , Sequência de Bases , China , Fases de Leitura Aberta , Filogenia , Podoviridae/classificação , Podoviridae/isolamento & purificaçãoRESUMO
Bacteriophages and their derivatives are continuously gaining impetus as viable alternative therapeutic agents to control harmful multidrug-resistant bacterial pathogens, particularly in the food industry. The reduced efficacy of conventional antibiotics has resulted in a quest to find novel alternatives in the war against infectious disease. This study describes the full-genome sequence of Cronobacter phage vB_CsaP_Ss1, with subsequent cloning and expression of its endolysin, capable of hydrolysing Gram-negative peptidoglycan. Cronobacter phage vB_CsaP_Ss1 is composed of 42â205 bp of dsDNA with a G+C content of 46.1âmol%. A total of 57 ORFs were identified of which 18 could be assigned a putative function based on similarity to characterized proteins. The genome of Cronobacter phage vB_CsaP_Ss1 showed little similarity to any other bacteriophage genomes available in the database and thus was considered unique. In addition, functional analysis of the predicted endolysin (LysSs1) was also investigated. Zymographic experiments demonstrated the hydrolytic activity of LysSs1 against Gram-negative peptidoglycan, and this endolysin thus represents a novel candidate with potential for use against Gram-negative pathogens.
Assuntos
Bacteriófagos/genética , Parede Celular/efeitos dos fármacos , Cronobacter/virologia , Endopeptidases/genética , Endopeptidases/metabolismo , Bactérias Gram-Negativas/efeitos dos fármacos , Peptidoglicano/metabolismo , Composição de Bases , Parede Celular/metabolismo , DNA Viral/química , DNA Viral/genética , Genoma Viral , Hidrólise , Dados de Sequência Molecular , Fases de Leitura Aberta , Controle Biológico de Vetores/métodos , Análise de Sequência de DNARESUMO
Cronobacter spp. are opportunistic pathogenic bacteria that are responsible for severe infections in neonates. Powdered infant formula was confirmed to be the source in some cases. Bacteriophages offer a safe means for eliminating this pathogen. In the present study, we investigated the growth parameters and genome organization of a new bacteriophage, Dev2, isolated from sewage. The Dev2 phage contains DNA with a length of 39 kb and belongs to the T7 branch of the subfamily Autographivirinae, with the highest degree of identity to the phage K1F. The host specificity of Dev2 is limited to C. turicensis strains of the CT O:1 serotype. With a lower efficiency, this phage also infects some Salmonella and E. coli strains. The Dev2 phage can inactivate sensitive Cronobacter strains in reconstituted milk formula. The results obtained in this study are an important prerequisite for application of Dev2 in food control.
