bacteria farming amoeba

Wired | Colonies of a bizarre microbial goo have been found practicing agriculture at a scale tinier than any seen before.

Animals such as ants, snails and beetles are known to farm fungus. But the slime mold’s bacterial-farming trick takes it into a whole new realm..

“If you can pack your food source with you, it’s a serious advantage,” said molecular biologist Debra Brock of Rice University, co-author of the slime-mold study, published Jan. 19 in Nature.

Dictyostelium discoideum, the best-known of a group of creatures called slime molds, spends part of its life as a single-celled amoeba feeding on bacteria that grow in decomposing leaves on forest floors.

When food is short, hundreds of thousands of amoebas come together, fusing into a single entity. It may crawl off as a slug in search of richer pastures, then form a stalk topped by a “fruiting body” that bursts to disperse a few lucky amoebas-turned-spores. Or it may form the stalk right away, without crawling.

It’s been thought that slime molds simply scavenge, eating bacteria they like and oozing out the rest. In laboratories, researchers “cure” slime molds of their bacteria by allowing them to purge themselves on Petri dishes. But Brock, who studies how slime-mold cells communicate and self-organize, kept finding bacteria in the fruiting bodies of some slime molds and not others.

When grown in the lab, the unusual fruiting bodies grew both the slime mold and the bacteria.

“The typical response to finding two species in a culture is, ‘Ick, I don’t want this!’” said evolutionary biologist Kevin Foster of Oxford University, who wasn’t involved in the study. “[Brock's team] had the insight to realize this was more than a simple contamination, that something else was going on here.” Fist tap Dale.