Bacteriophages represent a promising alternative to antibiotics, however, their efficient production depends on the physiological state of the host bacteria. This master's thesis aimed to establish at least partial synchronization of an Escherichia coli culture using the cyclic fed-batch technique, and to evaluate the influence of the synchronization cycle phase on the reproduction efficiency of bacteriophages T4. The synchronization was carried out in a chemically defined medium in which, after each doubling of the bacterial population, half of the culture broth was removed and replaced with a fresh medium. The progress of the process was monitored by measuring dissolved oxygen, optical density, and the number of viable bacteria (CFU). The degree of synchronization was evaluated using Blumenthal’s and Zahler’s synchronization index, which was calculated based on the experimentally obtained CFU values. To determine the influence of the physiological state of the bacteria on phage reproduction, infection experiments with bacteriophage T4 were performed at various time points of the synchronization cycle. Cyclic cultivation enabled repeatable growth cycles, in which most cell divisions were concentrated in the second half of the cycle, confirming the achieved partial synchronization of the bacterial population. It has also been proved that synchronization of the bacterial culture has influence on the success of phage reproduction. When infection occurred at the optimal point of the synchronization cycle, the adsorption constant does not change and burst size increased, while the latent period was shortened. The obtained results provide a basis for optimizing bacteriophage production.
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