Improving phage titre through examining point of infection

Abstract

Bacteriophages are viruses that cause the lysis of bacteria. They have recently been used to combat antimicrobial resistant infections as an alternative therapy to antibiotics. Their production and propagation, however, remains understudied and will be key to obtaining titres required for future clinical studies and research. Previous work suggests that temperature of infection significantly influences the production process and output yield of phage, with a reduction in temperature from 37ºC to 28ºC resulting in significant increases in productivity for multiple host-phage systems. The current study aimed to build upon this previous work by examining different temperature conditions at the point of infection to determine the effect on harvest phage titre improvements. Investigations were conducted at different culture scales ranging from 20mL shake flasks to 3L stirred tank bioreactor cultures to investigate process differences when scaling from laboratory bench-scale to initial industrial scale fermentations. Additionally, the kinetics of phage infection were investigated. In small scale cultures, the greatest phage bursts and harvest titres were generated by maintaining cultures under static 28 o C incubation during infection compared to agitation and temperature reduction from 37 o C. Investigating the dynamics around the point of infection will help to inform scalable processes for manufacture of phage for a variety of applications ranging from direct therapeutic application to self-assembling bio-templates for nanostructure synthesis.

Manufacturing Bacteriophages (Part 1 of 2): Cell Line Development, Upstream, and Downstream Considerations

“…One historical study by Pollard et al demonstrated using different temperatures to obtain differential titers [49]. Another example is the lowering of the infection temperature for E. coli-T4 [50,51]. Grieco et al reported that in a Design of Experiment study where the effect of DO, pH, and temperature was tested for optimal yield, the optimal theoretical yield (2.86 × 10 11 PFU/mL) was achieved at 28.1 • C and a pH of 6.9 which was validated with empirical studies (3.49 × 10 11 PFU/mL).…”