title: Formation and resuscitation of viable but nonculturable Salmonella typhi.
abstract: Salmonella typhi is a pathogen that causes the human disease of typhoid fever. The aim of this study was to investigate the viable but nonculturable (VBNC) state of S. typhi. Some samples were stimulated at 4°C or -20°C, while others were induced by different concentrations of CuSO4. Total cell counts remained constant throughout several days by acridine orange direct counting; however, plate counts declined to undetectable levels within 48 hours by plate counting at -20°C. The direct viable counts remained fairly constant at this level by direct viable counting. Carbon and nitrogen materials slowly decreased which indicated that a large population of cells existed in the VBNC state and entered the VBNC state in response to exposure to 0.01 or 0.015 mmol/L CuSO4 for more than 14 or 12 days, respectively. Adding 3% Tween 20 or 1% catalase enabled cells to become culturable again, with resuscitation times of 48 h and 24 h, respectively. The atomic force microscope results showed that cells gradually changed in shape from short rods to coccoids, and decreased in size when they entered the VBNC state. Further animal experiments suggested that resuscitated cells might regain pathogenicity.
authors.affiliation: School of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang 330013, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zeng
authors.forename: Guozhong
authors.initials: G
authors.lastname: Zhao
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Cao
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yang
authors.forename: Chunling
authors.initials: C
authors.lastname: Wang
authors.forename: Lihua
authors.initials: L
authors.lastname: Hou
mesh_terms: D000818:Animals; D001431:Bacteriological Techniques; D018929:Cell Culture Techniques; D015169:Colony Count, Microbial; D003470:Culture Media / Q000737:chemistry; D060766:Drinking Water / Q000382:microbiology; D051379:Mice; D050296:Microbial Viability; D018625:Microscopy, Atomic Force; D012485:Salmonella typhi / Q000472:pathogenicity / Q000502:physiology*; D014774:Virulence; D014871:Water Microbiology
chemical_list: D003470:Culture Media; D060766:Drinking Water