Light enhances survival of Dinoroseobacter shibae during long-term starvation

PLoS One. 2013 Dec 30;8(12):e83960. doi: 10.1371/journal.pone.0083960. eCollection 2013.

Abstract

Aerobic anoxygenic phototrophs (AAPs) as being photoheterotrophs require organic substrates for growth and use light as a supplementary energy source under oxic conditions. We hypothesized that AAPs benefit from light particularly under carbon and electron donor limitation. The effect of light was determined in long-term starvation experiments with Dinoroseobacter shibae DFL 12(T) in both complex marine broth and defined minimal medium with succinate as the sole carbon source. The cells were starved over six months under three conditions: continuous darkness (DD), continuous light (LL), and light/dark cycle (LD, 12 h/12 h, 12 µmol photons m(-2) s(-1)). LD starvation at low light intensity resulted in 10-fold higher total cell and viable counts, and higher bacteriochlorophyll a and polyhydroxyalkanoate contents. This coincided with better physiological fitness as determined by respiration rates, proton translocation and ATP concentrations. In contrast, LD starvation at high light intensity (>22 µmol photons m(-2) s(-1), LD conditions) resulted in decreasing cell survival rates but increasing carotenoid concentrations, indicating a photo-protective response. Cells grown in complex medium survived longer starvation (more than 20 weeks) than those grown in minimal medium. Our experiments show that D. shibae benefits from the light and dark cycle, particularly during starvation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / radiation effects
  • Cell Proliferation / radiation effects
  • Culture Media / chemistry*
  • Dose-Response Relationship, Radiation
  • Light*
  • Rhodobacteraceae / cytology*
  • Rhodobacteraceae / physiology
  • Rhodobacteraceae / radiation effects*

Substances

  • Culture Media

Grants and funding

This study has been funded by the German Science Foundation within the Collaborative Research Centre SFB-TRR51 (Roseobacter). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.