Variations in flow cytometric forward scatter signals and cell size in batch cultures of Escherichia coli

Abstract

Flow cytometry was used to study the lag, exponential, stationary and death phases of non-fixed cultures of Escherichia coli. Fluctuations in the forward angle scatter signal (FALS) were compared with cell size as measured by scanning electron microscopy at low temperature and image analysis. A correlation between FALS and cell size was not observed, although a correlation (r = -0.8) was obtained between FALS and the age of the culture for the first eleven days of incubation. Marked increases in FALS were observed during the lag phase, which were attributed both to changes in size and changes in structure or chemical composition. The distribution of FALS for all culture phases was asymmetric, and was associated with the cell size distribution.

Monitoring growth phase-related changes in phosphatidylcholine-specific phospholipase C production, adhesion properties and physiology of Bacillus cereus vegetative cells

“…As the lag phase continued, cells began adjusting to and altering their new environment [30], reXected by FCM proWles displaying a lesser degree of membrane damage, a greater percentage of cells with intracellular esterase activity and higher percentages of redox-active cells. These results agree with a previous FCM-based study, where E. coli cells were shown to adjust to their new environment through alterations in cell structure reXected by increases in FSC throughout the lag phase [7]. Upon entry into the exponential phase at 3 h, population proWles were largely unaltered until 8 h. Additionally, populations became more uniform, with the vast majority of cells being membrane intact, esterase positive and redox active.…”

“…To date, FCM has been applied to study lag times, numbers of cell divisions and the extent of injury of Lactobacillus plantarum [2], the physiology of Escherichia coli, Rhodococus spp. and Sacharomyces cerevisiae in batch and fed-batch fermentations [3,4], the population dynamics of B. licheniformis in batch and continuous cultures [5,6], forward scattered light (FSC) properties [7] glucose uptake [8], DNA content [9] and the appearance of "ghost cells" of E.coli during batch culture [10]. FCM has been applied to measure DNA and polyhydroxybutyrate content of Variovorax paradoxus [11] and Ralstonia eutropha during continuous culture [12] and the protein and nucleic acid content of B. subtilis [13].…”

Variation in cell-specific rates of leucine and thymidine incorporation by marine bacteria with high and with low nucleic acid content off the Oregon coast

“…Therefore, unlike Zubkov et al (2001), we did not find evidence that LNA cells could be more active on a biomass-specific basis. However, side scatter is not always correlated to cell volume (Christensen et al 1993, Hedal et al 1994, López-Amorós et al 1994. A better indication of cell volume would require sorting HNA and LNA cells, and independently determining their cell volume using epifluorescence microscopy.…”

Fluorescence monitoring of antibiotic-induced bacterial damage using flow cytometry

“…Reduced viability of the bacteria resulted in changes to their FALS. Light scatter is affected by total protein, cytoplasmic granularity, and other factors (22), although poor correlation between FALS and bacterial size has been demonstrated (23). However, its inclusion in the presentation of the data allows a better visualization of any subpopulations which may develop during antibiotic exposure.…”