A scaled-down model for the translation of bacteriophage culture to manufacturing scale

Therapeutic bacteriophages are emerging as a potential alternative to antibiotics and synergistic treatment of antimicrobial-resistant infections. This is reflected by their use in an increasing number of recent clinical trials. Many more therapeutic bacteriophage is being investigated in preclinical research and due to the bespoke nature of these products with respect to their limited infection spectrum, translation to the clinic requires combined understanding of the biology underpinning the bioprocess and how this can be optimized and streamlined for efficient methods of scalable manufacture. Bacteriophage research is currently limited to laboratory scale studies ranging from 1-20 ml, emerging therapies include bacteriophage cocktails to increase the spectrum of infectivity and require multiple large-scale bioreactors (up to 50 L) containing different bacteriophage-bacterial host reactions. Scaling bioprocesses from the milliliter scale to multi-liter large-scale bioreactors is challenging in itself, but performing this for individual phage-host bioprocesses to facilitate reliable and robust manufacture of phage cocktails increases the complexity. This study used a full factorial design of experiments approach to explore key process input variables (temperature, time of infection, multiplicity of infection, agitation) for their influence on key process outputs (bacteriophage yield, infection kinetics) for two bacteriophage-bacterial host bioprocesses (T4 - Escherichia coli; Phage K - Staphylococcus aureus). The research aimed to determine common input variables that positively influence output yield and found that the temperature at the point of infection had the greatest influence on bacteriophage yield for both bioprocesses. The study also aimed to develop a scaled down shake-flask model to enable rapid optimization of bacteriophage batch bioprocessing and translate the bioprocess into a scale-up model with a 3 L working volume in stirred tank bioreactors. The optimization performed in the shake flask model achieved a 550-fold increase in bacteriophage yield and these improvements successfully translated to the large-scale cultures

Bioinspired poly(vinylidene fluoride) membranes with directional release of therapeutic essential oils

Here, the morphology of polypore fungi has inspired the fabrication of poly(vinylidene fluoride) (PVDF) membranes with dual porosity by nonsolvent-induced phase separation (NIPS). The fruiting body of such microorganisms is constituted of two distinct regions, finger- and sponge-like structures, which have been successfully mimicked by controlling the coagulation bath temperature during the NIPS process. The use of water at 10 °C as coagulant resulted in membranes with the highest finger-like/sponge-like ratio (53% of the total membrane thickness), while water at 90 °C allowed the formation of macrovoid-free membranes. The microchannels and the asymmetric porosity were used to enhance the oil sorption capacity of the PVDF membranes and to achieve directional release of therapeutic essential oils. These PVDF membranes with easily tuned asymmetric channel-like porosity and controlled pore size are ideal candidates for drug delivery applications