The Human Frontier Science Program (HFSP) has awarded a grant to evolutionary biologist Arjan de Visser from Wageningen University and three international partners. The grant – worth 1.35 million dollars – will fund research on bacterial interactions and bacterial evolution in micro-ecosystems, nanodroplets of 100 nL.
The research team was awarded the grant in recognition of its project Interrogating Bacterial Social Interactions in Droplets, which examined the substances secreted by micro-organisms and their impact on the evolution of other micro-organisms in close proximity. The researchers working alongside De Visser come from wide-ranging disciplines from the New Zealand Institute for Advanced Study at Massey University in New Zealand, the Colloids and Dispersed Materials Laboratory at ESPCI ParisTech and the Department of Chemical Engineering at Technion in Israel.
The international team uses computer models and an advanced drip system to create and monitor ‘micro-ecosystems’. Each system is a droplet of only 100 nanolitres. Each droplet can acquire a specific composition. The growth of micro-organisms in the micro-ecosystems is monitored continuously by leading the droplets past sensors at ten-minute intervals. At the end of an experiment, specific droplets can be selected and ‘transgrafted’ to new droplets. This technique allows evolution to take place across multiple generations and enables hundreds of micro-ecosystems to be monitored at the same time.
De Visser and his colleagues are particularly interested in two extracellular substances. The first is an enzyme which degrades antibiotics in such a way that the bacteria that makes and secretes the enzyme is resistant to the antibiotic. The second extracellular substance helps bacteria with the absorption of iron.
Each substance has a specific impact on the ‘fitness’ of the bacteria. The next step is to examine the impact on congeners in the immediate environment and to ascertain how the interactions influence evolution.