Bacteria-phage symbioses are ubiquitous in nature and serve as valuable biological models. Historically, the ecology and evolution of bacteria-phage systems have been studied in either very simple or very complex communities. Although both approaches provide insight, their shortcomings limit our understanding of bacteria and phages in multispecies contexts. To address this gap, here we synthesize the emerging body of bacteria-phage experiments in medium-complexity communities, specifically those that manipulate bacterial community presence. Generally, community presence suppresses both focal bacterial (phage host) and phage densities, while sometimes altering bacteria-phage ecological interactions in diverse ways. Simultaneously, community presence can have an array of evolutionary effects. Sometimes community presence has no effect on the coevolutionary dynamics of bacteria and their associated phages, whereas other times the presence of additional bacterial species constrains bacteria-phage coevolution. At the same time, community context can alter mechanisms of adaptation and interact with the pleiotropic consequences of (co)evolution. Ultimately, these experiments show that community context can have important ecological and evolutionary effects on bacteria-phage systems, but many questions still remain unanswered and ripe for additional investigation.

Characterization of microbial growth is of both fundamental and applied interest. Modern platforms can automate collection of high-throughput microbial growth curves, necessitating the development of computational tools to handle and analyze these data to produce insights. However, existing tools are limited. Many use parametric analyses that require mathematical assumptions about the microbial growth characteristics. Those that use non-parametric or model-free analyses often can only quantify a few traits of interest, and none are capable of importing and reshaping all known growth curve data formats. To address this gap, here I present a newly-developed R package: gcplyr. gcplyr can flexibly import growth curve data in every known format, and reshape it under a flexible and extendable framework so that users can design custom analyses or plot data with popular visualization packages. gcplyr can also incorporate metadata and generate or import experimental designs to merge with data. Finally, gcplyr carries out model-free and non-parametric analyses, extracting a broad range of clinically and ecologically important traits, including initial density, lag time, growth rate and doubling time, carrying capacity, diauxie, area under the curve, extinction time, and more. In sum, gcplyr makes scripted analysis of growth curve data in R straightforward, streamlines common data wrangling and analysis steps, and easily integrates with common visualization and statistical analyses.

Antibiotic resistant bacterial pathogens are increasingly prevalent, driving the need for alternative approaches to chemical antibiotics when treating infections. One such approach is bacteriophage therapy: the use of bacteria-specific viruses that lyse (kill) their host cells. Just as the effect of environmental conditions (e.g. elevated temperature) on antibiotic efficacy is well-studied, the effect of environmental stressors on the potency of phage therapy candidates demands examination. Therapeutic phage OMKO1 infects and kills the opportunistic human pathogen Pseudomonas aeruginosa. Here, we used phage OMKO1 as a model to test how environmental stressors can lead to damage and decay of virus particles. We assessed the effects of elevated temperatures, saline concentrations, and urea concentrations. We observed that OMKO1 particles were highly tolerant to different saline concentrations, but decayed more rapidly at elevated temperatures and under high concentrations of urea. Additionally, we found that exposure to elevated temperature reduced the ability of surviving phage particles to suppress the growth of P. aeruginosa, suggesting a temperature-induced damage. Our findings demonstrate that OMKO1 is highly tolerant to a range of conditions that could be experienced inside and outside the human body, while also showing the need for careful characterization of therapeutic phages to ensure that environmental exposure does not compromise their expected potency, dosing, and pharmacokinetics.

13Antibiotic resistant bacterial pathogens are increasingly prevalent, driving the need for alternative 14 approaches to chemical antibiotics when treating infections. One such approach is bacteriophage 15 therapy: the use of bacteria-specific viruses that lyse (kill) their host cells. However, while the effect of 16 environmental conditions (e.g. elevated temperature) on antibiotic efficacy is well-studied, the 17 generalized effects of environmental stressors on the potency of phage therapy candidates are seldom 18 studied. Therapeutic phage OMKO1 infects and kills the opportunistic human pathogen Pseudomonas 19 aeruginosa, while selecting for the evolution of antibiotic re-sensitivity in the target bacterial 20population. Here, we used phage OMKO1 as a model to test how a therapeutic virus degrades in 21 different environments, and whether exposure to an environmental stressor affects subsequent growth 22 ability on host bacteria. We observed that OMKO1 particles were highly tolerant to different saline 23concentrations, but rapidly deactivated at elevated temperatures and under high concentrations of 24 urea. We also found that exposure to elevated temperature reduced the growth ability of surviving 25 OMKO1 particles, suggesting a temperature-induced phenotypic shift. Our findings demonstrate that 26 OMKO1 is highly tolerant to a range of conditions that could be experienced in and outside the human 27 body, while also showing the need for careful characterization of therapeutic phages to ensure that 28 environmental exposure does not compromise their expected potency, dosing, and pharmacokinetics. 29