LAUSR

AIMS To measure the infectious titer (IT) decay rate for various bacteriophages as a function of storage container material. Additionally, parallel light scattering and infectious titer measurements reveal distinct mechanisms for IT loss, depending on phage. METHODS AND RESULTS Suspensions of bacteriophages 44AHJD, P68, and gh-1 were stored in various labware. IT of each suspension was repeatedly measured over the course of two weeks. Large variability in IT decay was observed, with >4 log10 loss in glass and low-binding polypropylene. Incubation of polymer containers with Bovine Serum Albumin (BSA) resulted in a consistent reduction in IT decay. Aggregation state of phage suspensions was studied by nanoparticle tracking analysis (NTA), revealing highest aggregation in glass-stored suspensions and lowest after storage in BSA-treated containers. CONCLUSIONS Glass and "low-binding" containers may aggravate IT decay while BSA treatment may present an easy mitigation strategy. IT vs. NTA titer diagrams highlight the importance of phage inactivation in combination with aggregation. SIGNIFICANCE AND IMPACT OF THE STUDY Container material is a significant determinant of bacteriophage IT decay. It is therefore essential to confirm IT following storage and tailor choice of phage storage containers accordingly. Aggregation of phages and adsorption onto labware surfaces are not the only mechanisms accounting for IT loss, but also biological instability.