Microbe economics is ruthless and exploitative

Microbes develop their own economies, according to new research – and their outcomes can be just as dismal as human ones.

Writing in the journal Nature Communications, a team led by Eric Libby of the Santa Fe Institute, US, describes how multi-species microbial communities effectively trade or compete for commodities. In the economies that thus emerge, there are winners and losers in terms of inter-species interaction – some microbes are effectively exploited by others – and the outcomes can affect the growth of each community as a whole.

Libby and his team identify a number of paradoxes that arise from species interaction. In the microbial world, it seems, the free market can be brutal.

The economies arise because microbes produce most of the metabolic resources they need to survive. Due to the fact that they have permeable cell walls, however, a proportion of those in-house resources leak out into the open world, where they are available for use by other species.

The other species can then adapt to exploit these ready-made resources and free themselves from the tasks of manufacturing them. At the same time, of course, the first species in this example can also take advantage of different resources spilling out from others.

Libby describes this scenario as the “curse of increased inefficiency”. As Organism A leaks a useful metabolite, Organism B uses it and ceases to make it itself. As a result, Organism B can divert that portion of its energy budget to other tasks, such as reproduction, and ends up outnumbering Organism A.

The scientists also posit a paradox they call “the curse of control”. In this scenario, Organism A manipulates Organism B into essentially doing its bidding by producing excess of a desired resource.

In the short-term in this scenario Organism A profits and increases in numbers. In the long-term, however, it suffers disproportionate losses.

 “Depending on the length of time of an association, it may be more beneficial to compete with another microbe than to exploit it,” the scientists write.

The findings may offer insight into improving ways of managing microbial colonies constructed for industrial purposes, such as power generation or environmental remediation.