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

Bożena Bruhn-Olszewska , Paweł Szczepaniak , Ewelina Matuszewska , Dorota Kuczyńska-Wiśnik , Karolina Stojowska-Swędrzyńska , Maria Moruno Algara , Ewa Laskowska

Abstract

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 HD50 subpopulation was decreased and culturability of the LD50 subpopulation was significantly increased. In both subpopulations the level of protein aggregates formed under anaerobic and aerobic heat stress was comparable. We concluded that the formation of protein aggregates was independent of oxidative damage induced by heat stress, and that oxidative stress and not protein aggregation limited growth and caused loss of LD50 culturability. Our results indicate that heat stress induces the formation of distinct subpopulations differing in their ability to grow under standard and stress conditions.
Author Bożena Bruhn-Olszewska (FB / DMGB)
Bożena Bruhn-Olszewska,,
- Department of Molecular Genetics of Bacteria
, Paweł Szczepaniak (FB)
Paweł Szczepaniak,,
- Faculty of Biology
, Ewelina Matuszewska (FB / DB)
Ewelina Matuszewska,,
- Department of Biochemistry
, Dorota Kuczyńska-Wiśnik (FB / DB)
Dorota Kuczyńska-Wiśnik,,
- Department of Biochemistry
, Karolina Stojowska-Swędrzyńska (FB / DB)
Karolina Stojowska-Swędrzyńska,,
- Department of Biochemistry
, Maria Moruno Algara (FB / DB)
Maria Moruno Algara,,
- Department of Biochemistry
, Ewa Laskowska (FB / DB)
Ewa Laskowska,,
- Department of Biochemistry
Journal seriesMicrobiological Research, ISSN 0944-5013, (A 25 pkt)
Issue year2018
Vol209
Pages33-42
Publication size in sheets0.5
Keywords in Englishpopulation heterogeneity, heat stress, protein oxidation, VBNC cells, persisters
DOIDOI:10.1016/j.micres.2018.02.002
URL https://doi.org/10.1016/j.micres.2018.02.002
Languageen angielski
Score (nominal)25
ScoreMinisterial score = 25.0, 09-10-2018, ArticleFromJournal
Ministerial score (2013-2016) = 25.0, 09-10-2018, ArticleFromJournal
Publication indicators WoS Impact Factor: 2016 = 3.037 (2) - 2016=3.136 (5)
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