MICROBIAL ECOLOGY OF SOILS FROM WILKES LAND, ANTARCTICA : I. THE BACTERIAL POPULATION AND ITS ACTIVITY IN RELATION TO DISSOLVED ORGANIC MATTER (Eleventh Symposium on Polar Biology)

During a comprehensive research program carried out on soils from the Antarctic Continent (Casey Station, Wilkes Land) emphasis was laid on the bacterial population, its state of activity and corresponding relationships to particulate and dissolved organic nutrients. The bacterial population is characterized by epifluorescence microscopy with regard to different size classes and its variability. Organic nutrients are described by particulate organic nitrogen, carbon and particulate carbohydrates as well as by dissolved amino acids and monocarbohydrates. Bacterial activity is determined by uptake and respiration of labelled glucose. The results indicate a fairly active microbial population although actual numbers and biomass of bacteria show low levels in comparison with other environments. Dominant factors for bacterial activity (uptake of glucose and biomass production) are free dissolved monocarbohydrates and amino acids in connection with total organic carbon and moisture content. Respiration, however, shows a quite different pattern of variation. The most active part of the bacterial population is the size class of small rods (1-1.5 μm)