Cell aggregation in cultures of Micrococcus luteus, studied by dynamic light scattering

Cell aggregation was studied using the method of dynamic light scattering in the course of growth of Micrococcus luteus cultures in a liquid medium. The method detects particles ranging in size from 0.5 to 1000 mu m in samples containing no more than 10(5) cells/ml. When grown in liquid media, M. luteus forms aggregates; during the lag phase, 80% of the cells are found in aggregates of 10-1000 mu m, only minor amounts being represented by single cells. With the onset of exponential growth, the aggregates were decomposed and single cells became prevalent in the culture liquid. This observation confirms that the aggregation of the cells during the lag phase is prerequisite to the initiation of bacterial growth. The method may be used in biotechnology for monitoring the state of bacterial cultures.