Fine-scale microbial diversity and the individuality of the microbiome. Fine-scale diversity in bacteria is the diversity seen within traditionally accepted species boundaries. Recent studies have revealed a remarkable diversity of microbes in nature, and have provided insights into how fine-scale diversity emerges and how it is maintained in natural populations. Investigating the fine-scale diversity of host-associated microbes have revealed the remarkable individuality of these microbes, meaning that each individual animal, including each human being, hosts its own genetically unique microbiome. The next challenge is to understand how microbial fine-scale genetic diversity affects their function. Our research therefore relies on state-of-the-art techniques for quantifying microbial activity in nature. Our goal is to understand the role of fine-scale diversity in the functioning and evolutionary stability of host-microbe associations.
Microplastics (<5 mm particles) occur within both engineered and natural freshwater ecosystems, including wastewater treatment plants, lakes, rivers, and estuaries. While a significant proportion of microplastic pollution is likely sequestered within freshwater environments, these habitats also constitute an important conduit of microscopic polymer particles to oceans worldwide. The quantity of aquatic microplastic waste is predicted to dramatically increase over the next decade, but the fate and biological implications of this pollution are still poorly understood. A growing body of research has aimed to characterize the formation, composition, and spatiotemporal distribution of microplastic-associated (“plastisphere”) microbial biofilms. Plastisphere microorganisms have been suggested to play significant roles in pathogen transfer, modulation of particle buoyancy, and biodegradation of plastic polymers and co-contaminants, yet investigation of these topics within freshwater environments is at a very early stage. Here, what is known about marine plastisphere assemblages is systematically compared with up-to-date findings from freshwater habitats. Through analysis of key differences and likely commonalities between environments, we discuss how an integrated view of these fields of research will enhance our knowledge of the complex behavior and ecological impacts of microplastic pollutants.