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  • Effect of bacterial growth ...
    Nabergoj, Dominik; Modic, Petra; Podgornik, Aleš

    MicrobiologyOpen, April 2018, Letnik: 7, Številka: 2
    Journal Article

    It is important to understand how physiological state of the host influence propagation of bacteriophages (phages), due to the potential higher phage production needs in the future. In our study, we tried to elucidate the effect of bacterial growth rate on adsorption constant (δ), latent period (L), burst size (b), and bacteriophage population growth rate (λ). As a model system, a well‐studied phage T4 and Escherichia coli K‐12 as a host was used. Bacteria were grown in a continuous culture operating at dilution rates in the range between 0.06 and 0.98 hr−1. It was found that the burst size increases linearly from 8 PFU·cell−1 to 89 PFU·cell−1 with increase in bacteria growth rate. On the other hand, adsorption constant and latent period were both decreasing from 2.6∙10‐9 ml·min−1 and 80 min to reach limiting values of 0.5 × 10‐9 ml·min−1 and 27 min at higher growth rates, respectively. Both trends were mathematically described with Michaelis–Menten based type of equation and reasons for such form are discussed. By applying selected equations, a mathematical equation for prediction of bacteriophage population growth rate as a function of dilution rate was derived, reaching values around 8 hr−1 at highest dilution rate. Interestingly, almost identical description can be obtained using much simpler Monod type equation and possible reasons for this finding are discussed. Due to versatility of applications of bacteriophages and consequently potential higher phage production needs in the future, it is important to evaluate the effect of physiological state of the host on propagation of phages. In our study, we demonstrated on system phage T4 and Escherichia coli K‐12 growing in a continuous culture, that all phage growth parameters and consequently also bacteriophage population growth rate depends significantly on bacterial growth rate. The trends of each phage growth parameter and bacteriophage population growth rate were mathematically described enabling accurate prediction of bacteriophage propagation for specific bacterial growth rate and by this design of phage production process as well.