Starved bacteria retain their size but lose culturability - lessons from a 5000 years old undisturbed A-horizon

Research output: Contribution to journalLetterResearchpeer-review

  • Mette Vestergård
  • Ekelund, Flemming
  • Anne Winding
  • Carsten Suhr Jacobsen
  • Søren Christensen
The vast majority of soil bacteria are unable to form visible colonies on agar media. One hypothesis is that unculturable soil bacteria are dwarf cells that may either be small starved forms derived from larger species or represent inherently small species. We test the hypotheses that cells of extremely starved soil bacterial communities are smaller and less culturable than cells of bacterial communities from a richer soil, and that culturability is related to cell size by comparing an extremely starved community from a 5,200-year-old A-horizon buried under a burial mound with a community from a modern agricultural A-horizon.
We serially filtered cell suspensions through filters with successively smaller pore sizes (0.8 µm, 0.6 µm and 0.4 µm) and assessed total cell number and culturability, i.e. the ability to form colonies on two types of agar media, in each size fraction. Cell size distributions were assessed in unfiltered suspensions. Average cell size was only moderately reduced in the starved community, where culturability was low for all size classes. In contrast, culturability was much higher in the modern community, where culturability decreased dramatically with decreasing cell sizes.
Original languageEnglish
JournalSoil Biology & Biochemistry
Issue number6
Pages (from-to)1379-1382
Number of pages4
Publication statusPublished - 2011

ID: 32903123