Natures wonders: bacteria farm algae for food (Introduction)

by David Turell @, Sunday, July 03, 2016, 00:54 (1259 days ago) @ David Turell

Certain bacteria farm algae for food using pesticides to protect them:

"They're possibly the tiniest, most ancient gardeners in the world. A type of marine bacteria tends algae, using pesticides to keep other microbes away.


"Sonnenschein's work builds on a 2011 discovery by Mohammad Seyedsayamdost, now at Princeton University. He found that in times of plenty, the algae produce nutrients that help Roseobacter microbes thrive. In return, the bacteria make antibiotics which serve as pesticides, protecting the algae from rival bacterial strains.

"Both the bacteria and the algae appear to benefit from the arrangement, reminiscent of ants farming aphids. “I suspect it's mutualism,” says Rita Colwell of the University of Maryland at College Park. “They wouldn't be there if it wasn't beneficial to both parties.”

"When times get tougher, though, and the algae begin competing with the bacteria for resources, the “farmers” stop making antibiotics and instead produce a substance that kills off the algae, harvesting the rich algal decay products.

"Sonnenschein's team has now investigated the “tools” that the bacteria use to manage their algal gardens. These include a “herbicide”, tropodithietic acid (TDA), which protects the algae from other bacteria, and roseobacticides, the substances that kill off the algae for harvest.

"The team studied samples from aquaculture facilities in Denmark, Spain and Greece and from seawater off the coast of Denmark, Germany and Australia. They identified and studied strains of a particular species of Roseobacter called Phaeobacter inhibens, most of which produced roseobacticides.

"By comparing their genomes with those of the strains that did not, the researchers could home in on genes likely to be responsible for their production. They found that the microbes that make TDA aren't always also able to produce the compounds that kill algae. Indeed, they identified 41 gene clusters that are unique in those bacteria that can make roseobacticides."

Comment: Very similar to ants herding aphids. Not really symbiosis if you harvest and eat your partner.

It is thought that algal breakdown products induce more production of roseobacticides, creating a positive feedback loop that causes more algae to be killed off.

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