Analysis of Colony Forming Curves of Soil Bacteria

Abstract

By observing of the colony formation of soil bacteria on a plate, we found that the colony forming curves of soil bacteria were remarkably different from those of pure cultured bacteria; the colony forming curves of the soil bacteria showed several tiers of curves: in the case of upland and paddy soil bacteria, the curves showed 2 and 3 tiers, respectively. We obtained the isolates from the colonies composing each tier of curve and studied the physiological properties by using the first order reaction (FOR) model. Each tier of the colony forming curve was found to be composed by the group having a similar growth rate. The ratio of the population size and the difference of growth rate of each group were analyzed by the superposition of FOR models. Parameter tt of the FOR model was considered to reflect directly the growth rate.