Small but mighty: Experimenting with Earth’s Smallest Communities

Work package 2

Lead Investigator: Dr Tom Bell
Lead Postdoctoral Researcher: Dr Emma Ransome

Bacteria might be small but they underpin all life on Earth. They provide food for larger organisms, break down dead matter so that nutrients can be recycled, and can also be important pathogens. Bacterial communities are the foundation of aquatic food webs, in which they play important roles in the 'functioning' of ecosystems, including in the health and nutrition of plants, animals and other small organisms.

Although bacteria may appear simple, they form complex communities with huge taxonomic and functional biodiversity, which scientists are only beginning to uncover. The 'functioning' of ecosystems emerges from intricate interactions between hundreds of thousands of bacterial species. Though interactions may only occur between a few cells at a time, yet the outcome of these exchanges can have ramifications that spread rapidly throughout the ecosystem. These interactions can ultimately influence the higher trophic levels at the top of the food web. To provide critical new insights into the ecological consequences of climate change, our work investigates the ecological and evolutionary responses of bacteria to warming in freshwater ecosystems.

We will use bacterial communities collected from the sediment of dozens of geothermally warmed stream sites across the N. Hemisphere, to understand their role in ecosystem functioning. In the laboratory we will grow bacteria from these communities and investigate how they respond to changes in temperature and what this may mean for their natal ecosystems.

We will quantify the functioning of each species by measuring their growth, metabolic activity, respiration and their ability to process materials that can then be used by plants and animals for nutrition. This baseline information will allow us to gauge how microbes from different regions might adapt to warming over short and long time scales, and what this could mean for the wider ecosystem.      

For the first time we will be able to answer fundamental questions about whether responses to warming are universal or if they vary from place to place and how exactly they adapt – for instance, are diverse communities better, do they switch out their key players, or do we see evolution of particular bacteria to new environmental conditions?