scholarly journals Characterization of the genetic switch from phage ɸ13 important for Staphylococcus aureus colonization in humans

2021 ◽  
Vol 10 (5) ◽  
Author(s):  
Camilla S. Kristensen ◽  
Anders K. Varming ◽  
Helena A. K. Leinweber ◽  
Karin Hammer ◽  
Leila Lo Leggio ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Genetic Switch

scholarly journals Characterization of the genetic switch from phage phi13 important for Staphylococcus aureus colonization in humans

2021 ◽  
Author(s):  
Camilla Kristensen ◽  
Anders Varming ◽  
Helena Leinweber ◽  
Karin Hammer ◽  
Leila Lo Leggio ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Bacterial Genome ◽  
Host Factors ◽  
Human Pathogen ◽  
Switch Region ◽  
Genetic Switch ◽  
Dna Damaging Agents ◽  
Beta Galactosidase

Temperate phages are bacterial viruses that either reside integrated in a bacterial genome as lysogens or enter a lytic lifecycle. Decision between lifestyles is determined by a switch involving a phage-encoded repressor, CI, and a promoter region from which lytic and lysogenic genes are divergently transcribed. Here we investigate the switch of phage phi13 from the human pathogen Staphylococcus aureus. phi13 encodes several virulence factors and is prevalent in S. aureus strains colonizing humans. We show that the phi13 switch harbors a cI gene, a predicted mor (modulator of repression) gene, and three high-affinity operator sites binding CI. To quantify the decision between lytic and lysogenic lifestyle, we introduced reporter plasmids that carry the 1.3 kb switch region from phi13 with the lytic promoter fused to lacZ into S. aureus and B. subtilis. Analysis of beta-galactosidase expression indicated that decision frequency is independent of host factors. The white “lysogenic” phenotype, which relies on expression of cI, could be switched to a stable blue “lytic” phenotype by DNA damaging agents. We have characterized lifestyle decisions of phage phi13, and our approach may be applied to other temperate phages encoding virulence factors in S. aureus.

scholarly journals Characterization of the genetic switch from phage phi13 important for Staphylococcus aureus colonization in humans

2021 ◽  
Author(s):  
Camilla Kristensen ◽  
Anders Varming ◽  
Helena Leinweber ◽  
Karin Hammer ◽  
Leila Lo Leggio ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Bacterial Genome ◽  
Host Factors ◽  
Human Pathogen ◽  
Switch Region ◽  
Genetic Switch ◽  
Dna Damaging Agents ◽  
Beta Galactosidase

Temperate phages are bacterial viruses that either reside integrated in a bacterial genome as lysogens or enter a lytic lifecycle. Decision between lifestyles is determined by a switch involving a phage-encoded repressor, CI, and a promoter region from which lytic and lysogenic genes are divergently transcribed. Here we investigate the switch of phage phi13 from the human pathogen Staphylococcus aureus. phi13 encodes several virulence factors and is prevalent in S. aureus strains colonizing humans. We show that the phi13 switch harbors a cI gene, a predicted mor (modulator of repression) gene, and three high-affinity operator sites binding CI. To quantify the decision between lytic and lysogenic lifestyle, we introduced reporter plasmids that carry the 1.3 kb switch region from phi13 with the lytic promoter fused to lacZ into S. aureus and B. subtilis. Analysis of beta-galactosidase expression indicated that decision frequency is independent of host factors. The white “lysogenic” phenotype, which relies on expression of cI, could be switched to a stable blue “lytic” phenotype by DNA damaging agents. We have characterized lifestyle decisions of phage phi13, and our approach may be applied to other temperate phages encoding virulence factors in S. aureus.

Phylogeny Characterization of Seb Gene Encoding Enterotoxins in Staphylococcus aureus Isolated from Raw Milk and Cheese

2019 ◽  
Vol 9 (o3) ◽  
Author(s):  
Fatima N. Aziz ◽  
Laith Abdul Hassan Mohammed-Jawad
Keyword(s):  
Staphylococcus Aureus ◽  
Food Poisoning ◽  
Raw Milk ◽  
Staphylococcal Enterotoxin B ◽  
Human Pathogen ◽  
Conventional Pcr ◽  
Biochemical Tests ◽  
Specific Primers ◽  
Gene Encoding

Food poisoning due to the bacteria is a big global problem in economically and human's health. This problem refers to an illness which is due to infection or the toxin exists in nature and the food that use. Milk is considered a nutritious food because it contains proteins and vitamins. The aim of this study is to detect and phylogeny characterization of staphylococcal enterotoxin B gene (Seb). A total of 200 milk and cheese samples were screened. One hundred ten isolates of Staphylococcus aureus pre-confirmed using selective and differential media with biochemical tests. Genomic DNA was extracted from the isolates and the SEB gene detects using conventional PCR with specific primers. Three staphylococcus aureus isolates were found to be positive for Seb gene using PCR and confirmed by sequencing. Sequence homology showed variety range of identity starting from (100% to 38%). Phylogenetic tree analyses show that samples (6 and 5) are correlated with S. epidermidis. This study discovered that isolates (A6-RLQ and A5-RLQ) are significantly clustered in a group with non- human pathogen Staphylococcus agnetis.

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