Natures wonders: beetle uses bacteria for digestion (Introduction)

by David Turell , Thursday, November 16, 2017, 19:52 (2562 days ago) @ David Turell

A specialized beetle eating thistle leaves uses an onboard bacteria for digestion. Symbiosis at its best:

https://www.sciencedaily.com/releases/2017/11/171116132757.htm

"A leaf-eating beetle has evolved a symbiotic relationship with bacteria that allows the insect to break down pectin -- part of a plant's cell wall that is indigestible to most animals.

"'This insect is a leaf eater largely because of these bacteria," says Hassan Salem, lead author of the study and a post-doctoral fellow in Emory University's Department of Biology. "And the bacteria have actually become developmentally integrated into the insect's body."

"Two organs alongside the foregut of the beetle Cassida rubiginosa house the bacteria and appear to have no other function than to maintain these microbes. "The organs are equivalent to the liver in humans, in the sense that they contain the tools to break down and process food," Salem says.

"The newly characterized bacterium has only 270,000 DNA base pairs in its genome, compared to the millions that are more typical for bacterial strains. That makes its genome closer to that of intracellular bacteria and organelles than to free-living microbes. Mitochondria, for example, the organelles that regulate metabolism within cells, have 100,000 base pairs.

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"They used genome sequencing technology to characterize the microorganisms as a new species of bacterium. Despite its tiny genome, the bacterium has the power to degrade pectin.

"'Just as an apex predator has claws and strong mandibles to obtain the nutritional value that it needs from its prey, the bacterium has pectin-digesting genes that enable the beetle host to deconstruct a plant cell," Salem says.

"After the bacterium breaks down the pectin, the beetle's digestive system can then access all of the amino acids and vitamins within the plant's cells for its nutrients.

"Salem christened the new bacterium Candidatus Stammera capleta, after Hans-Jurgen Stammer, the ecologist who first glimpsed it and wondered about it more than 80 years ago."

Comment: One most wonder how this particular beetle ate before it found the helpful bacteria to take on board. Was it accidental or purposeful and helped by design?