Int J Biol Sci 2010; 6(4):303-315. doi:10.7150/ijbs.6.303
Survival of Escherichia coli under lethal heat stress by L-form conversion
Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev str. 26, 1113 Sofia, Bulgaria
Markova N, Slavchev G, Michailova L, Jourdanova M. Survival of Escherichia coli under lethal heat stress by L-form conversion. Int J Biol Sci 2010; 6(4):303-315. doi:10.7150/ijbs.6.303. Available from http://www.ijbs.com/v06p0303.htm
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.
Keywords: E. coli, lethal heat stress, L-form conversion