A Salvaging Strategy Enables Stable Metabolite Provisioning among Free-Living Bacteria.

All organisms rely on complex metabolites such as amino acids, nucleotides, and cofactors for essential metabolic processes. Some microbes synthesize these fundamental ingredients of life , while others rely on uptake to fulfill their metabolic needs. Although certain metabolic processes are inherently "leaky," the mechanisms enabling stable metabolite provisioning among microbes in the absence of a host remain largely unclear.

Emergence of Metabolite Provisioning as a By-Product of Evolved Biological Functions.

Microbes commonly use metabolites produced by other organisms to compete effectively with others in their environment. As a result, microbial communities are composed of networks of metabolically interdependent organisms. How these networks evolve and shape population diversity, stability, and community function is a subject of active research.

Bacterial coexistence driven by motility and spatial competition.

Elucidating elementary mechanisms that underlie bacterial diversity is central to ecology and microbiome research. Bacteria are known to coexist by metabolic specialization, cooperation and cyclic warfare. Many species are also motile, which is studied in terms of mechanism, benefit, strategy, evolution and ecology.

Multi-faceted approaches to discovering and predicting microbial nutritional interactions.

Nearly all microbes rely on other species in their environment to provide nutrients they are unable to produce. Nutritional interactions include not only the exchange of carbon and nitrogen compounds, but also amino acids and cofactors. Interactions involving cross-feeding of cobamides, the vitamin B family of cofactors, have been developed as a model for nutritional interactions across species and environments.

Evolutionary constraints in variable environments, from proteins to networks.

Environmental changes can not only trigger a regulatory response, but also impose evolutionary pressures that can modify the underlying regulatory network. Here, we review recent approaches that are beginning to disentangle this complex interplay between regulatory and evolutionary responses. Systematic genetic reconstructions have shown how evolutionary constraints arise from epistatic interactions between mutations in fixed environments.

Automated tracking in live-cell time-lapse movies.

The development of high-throughput live cell imaging is currently limited by the capabilities of image analysis. Software is required to generate single cell time courses from large data sets of time-lapse movies and to follow properties of individual cells. Automated cell tracking faces notorious problems associated with cell division, high cell density and cell mobility.

Predictive modeling of non-viral gene transfer.

In non-viral gene delivery, the variance of transgenic expression stems from the low number of plasmids successfully transferred. Here, we experimentally determine Lipofectamine- and PEI-mediated exogenous gene expression distributions from single cell time-lapse analysis. Broad Poisson-like distributions of steady state expression are observed for both transfection agents, when used with synchronized cell lines.