PARENT SESSION
Organized Oral Session 36: Role of microbial communities in mediating biogeochemical response to disturbance
Organizer(s): EAH Smithwick and MG Turner
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 511 B, Level 5, Palais des congrès de Montréal
Effects of the properties of the bacterial community on structure and function during recolonisation of a humus soil.
Pettersson, Marie1, Bååth, Erland*,1, 1 Department of Microbial Ecology, Lund, Sweden
ABSTRACT- A low pH humus soil was fumigated with chloroform for 4 h, after which only 1% of the initial bacterial activity remained. Half of the fumigated soil was then limed. Both the unlimed soil (UL) and the experimentally limed soil (EL) were then reciprocally inoculated with UL or field limed (FL) humus soil. The developing pH tolerance and the activity of the bacterial community were monitored during recolonisation using thymidine incorporation measurements in the different treatments (ULUL, ULFL, ELUL and ELFL, subscripts indicate inoculum source). The source of the inoculum had a significant impact on the function (pH tolerance and activity) of the bacterial community in the experimentally limed soil. The tolerance of the bacterial community to high pH was always higher in the ELFL soil than in the ELUL soil during up to 78 days incubation. The bacterial activity was also highest in the ELFL soil for the main duration of the experiment. The source of inoculum had little effect on the unlimed soils, since both the ULUL and the ULFL soils had the same low pH tolerance and bacterial activity. The differences in pH tolerance and activity between the EL soils inoculated with UL soil and FL soil were correlated to structural changes, as evidenced by both PLFA and DGGE analysis. There were, however, no differences between the soil bacterial communities in the UL soils with different inocula. This study showed the importance of the initial properties on the function of the microbial community after a perturbation event, and that there is a connection between the development of different functions and the structure of the bacterial community.
Key words: Inoculum source, Community pH adaptation, Community structure, Soil bacteria