Dos and Don’ts of Bacteriophage One-Step Growth

One-step growth experiments are powerful assays that can provide vital knowledge about the activity of bacteriophages, the viruses of bacteria or commonly just phages. The resulting curves provide determinations of phage latent periods and burst sizes, especially minimum latent periods and average burst sizes. These respectively are lengths of phage infections and numbers of new virions produced per infection, but which tend to vary with phage types, bacterial host strains, and experimental conditions. Though in principle one-step growth experiments are straightforward if labor-intensive assays, it is not obvious from published curves that their requirements for effective execution are fully appreciated by all. Here we address this latter point, in detail. We provide multiple suggestions – for improving how one-step growth determinations are performed – to achieve more precise and accurate phage latent period and burst size determinations. Our suggestions draw from a combination of practical experience and guidance available from other sources. Critiqued directly also are multiple Creative Commons-available examples of phage one-step growth. There we note, among other issues, that a common, fundamental error in published assays is a failure to dilute experimental cultures following phage adsorption, as can result in multi-step rather than one-step phage growth.