Communal Feeding Strategies Benefit Yeast

A team of scientists from the University of Exeter investigated why microorganisms spurn a survival-of-the-fittest mentality to instead adopt a seemingly risky communal strategy to acquire nutrients from their environment. Using Saccharomyces cerevisiae, also known as Brewer’s yeast, the researchers discovered the benefits that the communal strategy has on the population as a whole. The results were published yesterday in Nature Ecology & Evolution.

A common microbial feeding strategy involves the secretion of metabolic products into the surrounding environment, where they are broken down so that microbes in the community can recapture required nutrients. At first glance, this strategy appears to be flawed. Not only are some nutrients lost to the environment, but some are also exploited by neighboring microbes that take the benefits without sharing the workload.

But the new study illustrates one reason why microbes adopt this “public goods” approach rather than breaking down the nutrients inside the cell and keeping them for themselves. The researchers found that microbes that broke down nutrients internally rather than externally took over an otherwise stable population, leading it to become unstable and decline.

Along with investigating the microbes in their natural form and environment, the team also ran a series of sophisticated mathematical models and synthetic ecological experiments to determine why the “public goods” approach is so common in nature despite its flaws. “We were puzzled by the diversity of microbial feeding strategies observed in nature and created a synthetic microbial community to probe this further,” says senior author Ivana Gudelj.

The team found that strategies that break down nutrients either internally or externally both have their own selective benefits when considered in isolation. In communities containing a mixture of these feeding strategies, microbes that broke nutrients down internally out-competed their neighbors. However, such a selfish strategy became unsustainable once the “public goods” feeders had been out-competed.

“Through our interdisciplinary approach, we found that digesting resources externally is favored in fluctuating and rapidly changing environments or in non-diverse communities where they cannot be exploited,” explains first author Richard Lindsay.