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The measurement of an exponential bacterial growth curve in batch culture was traditionally a part of the training of all microbiologists; the basic means requires bacterial enumeration (cell counting) by direct and individual (microscopic, flow cytometry [1]), direct and bulk (biomass), indirect and individual (colony counting), or indirect ...
In the absence of antibiotics or other stressors, filamentation occurs at a low frequency in bacterial populations (4–8% short filaments and 0–5% long filaments in 1- to 8-hour cultures). [3] The increased cell length can protect bacteria from protozoan predation and neutrophil phagocytosis by making ingestion of cells more difficult.
In bacteria, both nutrients and waste products of metabolism reach the interior of the cell by diffusion, which places an upper limit on the size of these organisms. Cells of the large sulfur bacterium Thiomargarita namibiensis, discovered in 1999, contain a large sac filled with water and nitrates, which pushes most of the cytoplasm close to ...
As the cell size increases, they make proportionately less ATP, thus energy production limits their size. [3] Thiomargarita are an exception to this size constraint, as their cytoplasm forms along the periphery of the cell, while the nitrate-storing vacuoles occupy the center of the cell. [28] These vacuoles make up most of the cell.
As resources become more limited, the growth rate tapers off, and eventually, once growth rates are at the carrying capacity of the environment, the population size will taper off. [6] This S-shaped curve observed in logistic growth is a more accurate model than exponential growth for observing real-life population growth of organisms.
Bacterial cells are about one-tenth the size of eukaryotic cells and are typically 0.5–5.0 micrometres in length. However, a few species are visible to the unaided eye—for example, Thiomargarita namibiensis is up to half a millimetre long, [ 35 ] Epulopiscium fishelsoni reaches 0.7 mm, [ 36 ] and Thiomargarita magnifica can reach even 2 cm ...
There are two main types of bacterial cell walls, those of Gram-positive bacteria and those of Gram-negative bacteria, which are differentiated by their Gram staining characteristics. For both these types of bacteria, particles of approximately 2 nm can pass through the peptidoglycan. [ 3 ]
Bacteria function and reproduce as individual cells, but they can often aggregate in multicellular colonies. [54] Some species such as myxobacteria can aggregate into complex swarming structures, operating as multicellular groups as part of their life cycle , [ 55 ] or form clusters in bacterial colonies such as E.coli .