TY - JOUR
T1 - Growth response of soda lake bacterial communities to simulated rainfall
AU - Krammer, M.
AU - Velimirov, B.
AU - Fischer, U.
AU - Farnleitner, A. H.
AU - Herzig, A.
AU - Kirschner, A. K.T.
N1 - Funding Information:
Many thanks to Claudia Nemecz-Wieltschnig for substantial help in protozoan direct counting. Thanks also to the staff of the “Biologische Station Neusiedlersee” (Peter Gisch and Jutta Prückler) for the chemical analyses of the soda lake water. The project was financed by ENVIRO OEG, Eisenstadt, the Province of Burgenland (Project LW 621) and the Austrian “Naturschutzbund”.
PY - 2008/2
Y1 - 2008/2
N2 - Moderately saline soda lakes harbor extremely abundant and fast growing bacterial communities. An interesting phenomenon of an explosive bacterial growth in shallow soda lakes in Eastern Austria after dilution with rainwater, concomitantly with a significant decrease in temperature was observed in a former study. In the present study, we tried to identify the factors being responsible for this enhanced bacterial growth in laboratory batch cultures. Three experiments were performed with water taken from two different lakes at different seasons. Natural soda lake water was diluted with distilled water, artificial lake water, sterile filtered soda lake water, and grazer-free water to test (1) for the influence of compatible solutes released to the environment and reduced salt stress after osmotic down-shock, (2) for the influence of nutrients, which may be washed in from the dry areas of the lake bottom after rainfall and (3) for the decrease of grazing pressure due to dilution. The potential influence of (4) viruses was indirectly deduced. The response of the bacterial community to the manipulations was measured by changes in bacterial numbers, the incorporation of 3H-leucine and the concomitant determination of the amount of 3H-leucine uptaking bacteria by microautoradiography. The influence of the environmental factors enhancing bacterial growth after a simulated rainfall event showed variations between the lakes and over the seasons. The addition of nutrients was, in all experiments, the main factor triggering bacterial growth. The decrease in grazing pressure and viral lysis after dilution was of significant importance in two of three experiments. In the experiment with the highest salinity, we could show that either compatible solutes released after osmotic down-shock and used as a source of nutrients for the soda lake bacterial populations or reduced salt stress were most probably responsible for the observed marked enhancement of bacterial growth.
AB - Moderately saline soda lakes harbor extremely abundant and fast growing bacterial communities. An interesting phenomenon of an explosive bacterial growth in shallow soda lakes in Eastern Austria after dilution with rainwater, concomitantly with a significant decrease in temperature was observed in a former study. In the present study, we tried to identify the factors being responsible for this enhanced bacterial growth in laboratory batch cultures. Three experiments were performed with water taken from two different lakes at different seasons. Natural soda lake water was diluted with distilled water, artificial lake water, sterile filtered soda lake water, and grazer-free water to test (1) for the influence of compatible solutes released to the environment and reduced salt stress after osmotic down-shock, (2) for the influence of nutrients, which may be washed in from the dry areas of the lake bottom after rainfall and (3) for the decrease of grazing pressure due to dilution. The potential influence of (4) viruses was indirectly deduced. The response of the bacterial community to the manipulations was measured by changes in bacterial numbers, the incorporation of 3H-leucine and the concomitant determination of the amount of 3H-leucine uptaking bacteria by microautoradiography. The influence of the environmental factors enhancing bacterial growth after a simulated rainfall event showed variations between the lakes and over the seasons. The addition of nutrients was, in all experiments, the main factor triggering bacterial growth. The decrease in grazing pressure and viral lysis after dilution was of significant importance in two of three experiments. In the experiment with the highest salinity, we could show that either compatible solutes released after osmotic down-shock and used as a source of nutrients for the soda lake bacterial populations or reduced salt stress were most probably responsible for the observed marked enhancement of bacterial growth.
UR - http://www.scopus.com/inward/record.url?scp=38649083096&partnerID=8YFLogxK
U2 - 10.1007/s00248-007-9267-5
DO - 10.1007/s00248-007-9267-5
M3 - Journal article
C2 - 17619096
AN - SCOPUS:38649083096
SN - 0095-3628
VL - 55
SP - 194
EP - 211
JO - Microbial Ecology
JF - Microbial Ecology
IS - 2
ER -