Abstract
Abstract Sizes of individual cells in a Deinococcus radiodurans IR culture were measured by a Coulter size analyzer, and the resulted cell-particle-size distribution curves was found to display obvious peaks. A data modification system was used to render these peaks more distinguishable but at the same time causing no alternations in the basic traits of the distribution curve. The distinguishable peaks defined volumes as numeric (quantificational) data, thus help comparison study. For example, by using this size-distribution-data-processing approach, we were able to conclude that in comparison with its wild-type strain (IR), a slow-growing mutant strain (X2) was defective in the cell separation stages producing a much longer D phase. The results suggest that cell size increase in D. radiodurans was in tight control. Twenty-eight D. radiodurans IR cultures were similarly assayed and data modification system was used. Pooled results showed frequently occurring volumes (FOVs). Some FOVs constitute high-frequency regions in the cell size distribution curves. Based in the results, the pattern of the distinguishable peaks appears to be useful in studying cell growth physiology. The defined FOVs are suggestive of a tight cell-size control during the growth of a bacterial cell. In summary, cell-size increase during bacterial growth appears to be discontinuous in a stepwise fashion.