Assessment of physiological state of bacteria in the soil

Abstract

The number and physiological state (degree of membrane damage) of bacterial cells in alluvial meadow soil, soddy-podzolic soil, leached chernozem, and high moor peat were determined with the help of L7012 stain. The results suggest significant physiological heterogeneity of bacterial cells in the soils. The portion of intact cells reached 60–70% in freshly collected soil samples; 30–40% of cells had damaged membranes. Drying and freezing of soil samples decreased significantly the number of intact cells (to 10–20%) and increased the portion of cells with damaged membranes. Treatment with biocidal agents resulted in lysis of a significant part of cells and damage to the remaining cells. However, some cells preserved undamaged cell membranes and this testifies to the high resistance of bacteria in the soil. The data allow us to suggest a method for staining the soil suspension with L7012 as an express method that makes it possible to monitor the population density and the physiological state of the bacterial complex in the soil.