title: Survival of Escherichia coli under lethal heat stress by L-form conversion.
abstract: Transition of bacteria to cell wall deficient L-forms in response to stress factors has been assumed as a potential mechanism for survival of microbes under unfavorable conditions. In this article, we provide evidence of paradoxal survival through L-form conversion of E. coli high cell density population after lethal treatments (boiling or autoclaving). Light and transmission electron microscopy demonstrated conversion from classical rod to polymorphic L-form shape morphology and atypical growths of E. coli. Microcrystal formations observed at this stage were interpreted as being closely linked to the processes of L-form conversion and probably involved in the general phenomenon of protection against lethal environment. Identity of the morphologically modified L-forms as E. coli was verified by species specific DNA-based test. Our study might contribute to a better understanding of the L-form phenomenon and its importance for bacterial survival, as well as provoke reexamination of the traditional view of killing strategies against bacteria.
authors.affiliation: Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev str. 26, 1113 Sofia, Bulgaria. nadya.markova@gmail.com
authors.forename: Nadya
authors.initials: N
authors.lastname: Markova
authors.forename: Georgi
authors.initials: G
authors.lastname: Slavchev
authors.forename: Lilia
authors.initials: L
authors.lastname: Michailova
authors.forename: Mimi
authors.initials: M
authors.lastname: Jourdanova
mesh_terms: D004926:Escherichia coli / Q000502:physiology* / Q000648:ultrastructure*; D006358:Hot Temperature; D008853:Microscopy; D046529:Microscopy, Electron, Transmission; D013312:Stress, Physiological