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

TY - JOUR

T1 - Starved bacteria retain their size but lose culturability - lessons from a 5000 years old undisturbed A-horizon

AU - Vestergård, Mette

AU - Ekelund, Flemming

AU - Winding, Anne

AU - Jacobsen, Carsten Suhr

AU - Christensen, Søren

PY - 2011/6

Y1 - 2011/6

N2 - 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.

AB - 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.

U2 - 10.1016/j.soilbio.2011.02.008

DO - 10.1016/j.soilbio.2011.02.008

M3 - Letter

SN - 0038-0717

VL - 43

SP - 1379

EP - 1382

JO - Soil Biology & Biochemistry

JF - Soil Biology & Biochemistry

IS - 6

ER -