Community level physiological profile of soil bacteria unaffected by extraction method

Extraction and purification of bacteria from soil by the Nycodenz gradient centrifugation procedure described by Bakken and Lindahl (1995; Recovery of bacterial cells from soil. In: van Elsas, J.D., Trevors, J.T. (Eds.), Nucleic Acids in the Environment: Methods and Applications. Springer Verlag, Berlin, pp. 9-27) were compared to soil slurry extractions. Bacterial communities from four different soils were described by the bacterial abundance, CTC-reducing capacity, culturability and the community level physiological profiles (CLPP) in BIOLOG GN plates. A significant loss of both total and culturable number of bacteria g(-1) soil dry weight were found after extraction and purification of cells. The origin of soil influenced the yield of cells and a difference between the four soils and an interaction between the soils and extraction procedure were found. The culturability and the CLPP were different between the four soils but were unaffected by the extraction procedure. The bacterial community obtained after extraction and purification thus represented the same fraction of the indigenous bacterial community.