Does it flex before it breaks? Determining the roles of metabolic flexibility & species sorting in community response to a changing environment using denitrification as a model process

Approximately 160 Tg nitrogen passes through denitrification each year, with some fraction returning to the atmosphere as the greenhouse gas nitrous oxide rather than harmless dinitrogen.

Denitrification is a sequential three-step process executed either by a single “generalist” organism or a combination of “specialist” organisms encoding and/or expressing just a subset of those genes.

The conditions under which denitrification is dominated by “generalists” rather than “specialists” remains an open question, but there is some evidence that transitions between these lifestyles varies with carbon chemistry and degree of fertilization.

Here I will generate mock communities of Arabidopsis rhizosphere-derived bacterial isolates with varying degrees of denitrification generalism and subject them to different carbon sources and degrees of fertilization to assess how differences in pathway completeness are associated with nitrous oxide emission.

Using a novel high-throughput single-cell RNA sequencing method I will be able to determine whether generalist denitrifiers are acting as specialists and link electron donors and acceptors to specific genotypes, which will be used to inform how generalist and specialist denitrifiers interact in a trait-based model of microbial denitrification.

This project pushes the boundaries of interspecific interactions with respect to denitrification, while addressing the relative importance of community turnover and expression.