Starvation Induces Phenotypic Diversification and Convergent Evolution in Vibrio Vulnificus

PLoS One. 2014 Feb 13;9(2):e88658. doi: 10.1371/journal.pone.0088658. eCollection 2014.

Abstract

Starvation is a common stress experienced by bacteria living in natural environments and the ability to adapt to and survive intense stress is of paramount importance for any bacterial population. A series of starvation experiments were conducted using V. vulnificus 93U204 in phosphate-buffered saline and seawater. The starved population entered the death phase during the first week and approximately 1% of cells survived. After that the population entered a long-term stationary phase, and could survive for years. Starvation-induced diversification (SID) of phenotypes was observed in starved populations and phenotypic variants (PVs) appeared in less than 8 days. The cell density, rather than the population size, had a major effect on the extent of SID. SID was also observed in strain YJ016, where it evolved at a faster pace. PVs appeared to emerge in a fixed order: PV with reduced motility, PV with reduced proteolytic activity, and PV with reduced hemolytic activity. All of the tested PVs had growth advantages in the stationary phase phenotypes and increased fitness compared with 93U204 cells in co-culture competition experiments, which indicates that they had adapted to starvation. We also found that SID occurred in natural seawater with a salinity of 1%-3%, so this mechanism may facilitate bacterial adaptation in natural environments.

MeSH terms

  • Adaptation, Physiological*
  • Biological Evolution*
  • Caseins / chemistry
  • Colony Count, Microbial
  • Culture Media / chemistry
  • Culture Media / pharmacology*
  • Phenotype*
  • Protein Hydrolysates / chemistry
  • Seawater
  • Sodium Chloride
  • Vibrio vulnificus / drug effects*
  • Vibrio vulnificus / physiology

Substances

  • Caseins
  • Culture Media
  • Protein Hydrolysates
  • trypticase-soy broth
  • Sodium Chloride

Grant support

National Science Council grant NSC96-2311-B-320-004, (http://web1.nsc.gov.tw/). Tzu Chi University grant TCIRP96003-01, (http://www.tcu.edu.tw/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.