Viral diseases have caused devastating effect on poultry industry leading to significant losses in economy of world. In the presented study, the ability of Newcastle disease virus (NDV), infectious bursal disease virus (IBDV) and avian influenza virus (AIV) to grow in two cell lines was evaluated. Both chicken embryo fibroblast (CEF) and DF-1 cells were used and cytopathic effects (CPE) produced by these viruses were observed. The titer of virus in terms of TCID50 was determined after 24h up to four days for each virus. The same type of CPE was observed for all viruses used in the study in both DF-1 and CEF cells. IBDV showed CPE causing rounding of cells while NDV caused formation of multicellular large nuclei, cell fusion and rounding of cells. Giant cells with inclusions and aggregation of cells with intact monolayer was observed for AIV. In growth kinetic study, higher titer of IBDV and NDV was observed in CEF cells than DF-1 cells while for AIV, DF-1 cells showed higher titer than CEF cells. These results would be useful for furthers comparative studies on growth of different cell lines of various viruses to find a suitability for vaccine production.

In recent years, infections are more often caused by pathogens with high multi-drug resistance, classified as the “ESKAPE” microorganisms. Therefore, investigation of these pathogens, e.g., Klebsiella pneumoniae, often requires biomass production for treatment testing such as antibiotics or bacteriophages. Moreover, K. pneumoniae can be successfully applied as a biocatalyst for other industrial applications, increasing the need for this bacteria biomass. In the current study, we proposed a novel magnetically assisted bioreactor for the cultivation of K. pneumoniae cells in the presence of an external alternating magnetic field (AMF). High efficiency of the production requires optimal bacteria growth conditions, e.g., temperature and field frequency. Therefore, we performed an optimization procedure using a central composite design for these two parameters in a wide range. As an objective function, we utilized a novel, previously described growth factor that considers both biomass and bacteria growth kinetics. Thus, based on the response surface, we could specify the optimal growth conditions. Moreover, we analysed the impact of the AMF on bacteria proliferation, which indicated positive field frequency windows, where the highest stimulatory effect of AMF on bacteria proliferation occurred. Obtained results proved that the magnetically assisted bioreactor could be successfully employed for K. pneumoniae cultivation.