title: Survival, prophage induction, and invasive properties of lysogenic Salmonella Typhimurium exposed to simulated gastrointestinal conditions.
abstract: This study was designed to evaluate the viability, prophage induction, invasive ability, and relative gene expression in lysogenic Salmonella Typhimurium exposed to the simulated gastric juice (SGJ) at pH 2 (SGJ-2), 3 (SGJ-3), 4 (SGJ-4), and 5 (SGJ-5) for 30 min followed by 0.5 % bile salts for 2 h. The susceptibility of lysogenic S. Typhimurium increased with decreasing pH value and increasing bile salt concentration. The lysogenic S. Typhimurium cells were least susceptible to SGJ-4 and SGJ-5, showing <1 log reduction. The highest prophage induction was observed by 3.34 log PFU/ml in lysogenic S. Typhimurium at SGJ-3 in the presence of 0.5 % bile salts. The numbers of invading lysogenic S. Typhimurium treated at SGJ-3, SGJ-4, and SGJ-5 were 3.57, 3.73, and 4.15 log CFU/cm(2), respectively. Most genes (hilA, hilC, hilD, invA, invE, invF, and sirA) were down-regulated in lysogenic S. Typhimurium treated at SGJ-3, SGJ-4, and SGJ-5. This study provides useful information for understanding physiological changes of lysogenic S. Typhimurium in the simulated gastrointestinal conditions.
authors.affiliation: Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon, Gangwon, 200-701, Republic of Korea.
authors.forename: Songrae
authors.initials: S
authors.lastname: Kim
authors.forename: Kanghee
authors.initials: K
authors.lastname: Ryu
authors.forename: Debabrata
authors.initials: D
authors.lastname: Biswas
authors.forename: Juhee
authors.initials: J
authors.lastname: Ahn
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D005750:Gastric Juice / Q000737:chemistry / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D050296:Microbial Viability; D012486:Salmonella typhimurium / Q000235:genetics / Q000502:physiology* / Q000821:virology*; D014157:Transcription Factors / Q000378:metabolism; D014775:Virus Activation / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D014157:Transcription Factors