Maximizing yield, purity and throughput of M13 bacteriophage bioprocessing

The filamentous M13 bacteriophage has been used extensively as a building block for biomaterials fabrication due to its self-assembled structure and bulk assembling properties. With its genetic code encapsulated in its protein capsid, the M13 phage can be used in phage display or directed evolution mutagenesis for the creation of large libraries. Applying phage display to materials fabrication draws out bioprocessing challenges regarding high yields and high purity. Additionally, phage display introduces the need for high throughput production to parse mutant libraries. Here, we develop an optimized, high throughput process for upstream and downstream M13 phage production. We identify an optimal medium containing 17 g/L of both tryptone and yeast extract, maximizing phage production using standard polyethylene glycol/sodium chloride precipitation. Next, we add a centrifuge filtration step, which removes detectable traces of sodium ions and significantly lowers polyethylene glycol levels. The higher yields grown in the optimal medium remediate the loss of phages from added purification steps. We also applied this combined process to 96-well plates, recovering titers of purified phages proportional to those obtained with larger volumes. The method that we present here could allow for automatable, scalable M13 phage production for applications in genetically engineered biologically derived materials.