Effects of carbohydrates and leucine on growth of bacteria from Antarctic soils (Casey Station,Wilkes Land)

Growth rates of natural bacterial communities from Antarctic soils are analysed by an epifiuorescence microscopic method using data of microcolonies (colony number and colony areas). Incubations are performed on polycarbonate filters which are put on cellulose pads soaked with soil extracts, different concentrations of naturally occuring carbohydrates, polyols, and leucine. Concentrations of individual substrates were in the range of naturally occuring levels. The results showed that the growth of bacterial microcolonies could best be stimulated with glucose, sucrose, maltose, sorbitol, and mannitol. Leucine stimulated growth to a lower extent than glucose. Data on bacterial biomass production calculated from this approach are discussed in relation to those from tracer techniques carried out with ¹⁴C-labelled glucose from earlier experiments.