Bacteria trigger sex for single-celled sea creatures

Bacteria can be a potent aphrodisiac for the single-celled marine organisms known as choanoflagellates, which are the closest living relatives of animals.

Researchers at Harvard University found that the presence of the bioluminescent marine bacterium Vibrio fischeri triggers the choanoflagellate Salpingoeca rosetta to swarm and mate.

Why does V. fischeri put S. rosetta in the mood? It might be that the choanoflagellate interprets the presence of the bacteria as a sign that hard times are approaching.

“A lot of evolutionary theory favours the idea that mating happens when conditions are stressful, because you need to reshuffle the deck. With sexual reproduction, you will hopefully get a new combination of gene alleles that is more fit for whatever is coming down the pike,” says lead researcher Nicole King.

“Bacteria are very good at integrating a lot of information about the environment, as different species of bacteria have different nutrient requirements. Choanoflagellates may be using bacteria as a proxy for environmental conditions, or live indicators for when it’s time to get ready for good or bad times,” she said.

At a molecular level the mating is a response to a protein that the bacteria constantly secretes, which the researchers dubbed EroS.

The research is published in Cell.