Microbial Interactions: Cooperation

Cooperation is an interspecies interaction in which all participating organisms benefit compared to non-interaction, without obligate dependence on one another.

For example, juvenile parasitic nematodes, Steinernema carpocapsae, carry Xenorhabdus nematophila bacteria in their guts.

After infecting an insect host, the juvenile nematodes excrete the bacteria into the insect's body cavity.

There, the bacteria multiply and release toxins that kill the host within 24 to 48 hours, as well as antimicrobials that protect the cadaver from other microbes and ants.

Bacterial signals trigger nematode maturation, enabling adults to mate and lay their eggs inside the cadaver.

Fungi like Fusarium form hyphal networks in the soil, supporting the movement of bacteria like Pseudomonas putida.

The Fusarium hyphae secrete small amounts of water and mucilage, forming a thin, stable film that acts as a ‘highway' for bacterial travel.

Motile bacteria sense chemical signals from the hyphae and use water channels to migrate to new regions.

In return, bacteria enhance nutrient mobilization, increasing local nutrient availability for the fungus.