Physiologically distinct subpopulations formed in Escherichia coli cultures in response to heat shock

Publication date: Available online 13 February 2018 Source:Microbiological Research Author(s): Bożena Bruhn-Olszewska, Paweł Szczepaniak, Ewelina Matuszewska, Dorota Kuczyńska-Wiśnik, Karolina Stojowska-Swędrzyńska, María Moruno Algara, Ewa Laskowska Bacteria can form heterogeneous populations containing phenotypic variants of genetically identical cells. The heterogeneity of populations can be considered a bet-hedging strategy allowing adaptation to unknown environmental changes – at least some individual subpopulations or cells might be able to withstand future adverse conditions. Using Percoll gradient centrifugation, we demonstrated that in an Escherichia coli culture exposed to heat shock at 50 °C, two physiologically distinct subpopulations were formed. A high-density subpopulation (HD50) demonstrated continued growth immediately after its transfer to LB medium, whereas the growth of a low-density subpopulation (LD50) was considerably postponed. The LD50 subpopulation contained mainly viable but non-culturable bacteria and exhibited higher tolerance to sublethal concentrations of antibiotics or H2O2 than HD50 cells. The levels of aggregated proteins and main molecular chaperones were comparable in both subpopulations; however, a decreased number of ribosomes and a significant increase in protein oxidation were observed in the LD50 subpopulation as compared with the HD50 subpopulation. Interestingly, under anaerobic heat stress, the formation of the ...
Source: Microbiological Research - Category: Infectious Diseases Source Type: research