Nutrient transitions are a source of persisters in Escherichia coli biofilms

PLoS One. 2014 Mar 25;9(3):e93110. doi: 10.1371/journal.pone.0093110. eCollection 2014.

Abstract

Chronic and recurrent infections have been attributed to persisters in biofilms, and despite this importance, the mechanisms of persister formation in biofilms remain unclear. The plethora of biofilm characteristics that could give rise to persisters, including slower growth, quorum signaling, oxidative stress, and nutrient heterogeneity, have complicated efforts to delineate formation pathways that generate persisters during biofilm development. Here we sought to specifically determine whether nutrient transitions, which are a common metabolic stress encountered within surface-attached communities, stimulate persister formation in biofilms and if so, to then identify the pathway. To accomplish this, we established an experimental methodology where nutrient availability to biofilm cells could be controlled exogenously, and then used that method to discover that diauxic carbon source transitions stimulated persister formation in Escherichia coli biofilms. Previously, we found that carbon source transitions stimulate persister formation in planktonic E. coli cultures, through a pathway that involved ppGpp and nucleoid-associated proteins, and therefore, tested the functionality of that pathway in biofilms. Biofilm persister formation was also found to be dependent on ppGpp and nucleoid-associated proteins, but the importance of specific proteins and enzymes between biofilm and planktonic lifestyles was significantly different. Data presented here support the increasingly appreciated role of ppGpp as a central mediator of bacterial persistence and demonstrate that nutrient transitions can be a source of persisters in biofilms.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biofilms / growth & development*
  • Carbon / metabolism
  • Culture Techniques
  • Escherichia coli / enzymology
  • Escherichia coli / metabolism
  • Escherichia coli / physiology*
  • Ligases / metabolism
  • Transcription Factor RelA / metabolism

Substances

  • Transcription Factor RelA
  • Carbon
  • Ligases
  • guanosine 3',5'-polyphosphate synthetases

Grant support

This work was supported by the National Science Foundation (SMA, Graduate Research Fellowship), the Department of the Army (W81XWH-12-2-0138), and with start-up funds from Princeton University. This research was supported by the National Science Foundation Division of Materials Research through the Princeton University MRSEC (NSF-DMR 0819860). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.