The Microorganism That Puts the Sour in Dough, and Another That Eats Nuclear Waste for Lunch

Bacteria’s starring economic role.

The Tree of Life was a biological model originally proposed by Charles Darwin, suggesting that all living things originally came from one common ancestor.

Drawing a diagram of an elementary tree in his 1837 notebook, Darwin wrote “I think” at the top of the page.

Presumably this was an indication of it being a hypothesis, rather than him writing a simple two-word job description.

Since Darwin’s original, the Tree of Life has continuously evolved, but this has usually happened in small steps. However, a new paper reports a revised view of the Tree of Life that requires some big jumps beyond the one we’ve known and loved.

We already knew that almost all the lifeforms we’re familiar with belong on one slender branch.

This includes you, llamas, lemons, and lichens.

But scientists in the US and Canada have now observed that the great majority of the tree is actually home to prodigious numbers of bacteria.

Yup, it turns out we live on a planet where the microbes rule the roost, at least in terms of sheer numbers.

So far, many of these bacteria are a complete mystery, but at a time when bacterial diversity is getting almost as much media coverage as the Presidential race (well, almost) I’d like to shine a spotlight on a bunch of bacteria that do amazing jobs for humankind.

Consider their potential contribution to clearing up nuclear waste, for example.

British scientists have shown the viability of recovering uranium from tainted water using E. coli alongside inositol phosphate, a chemical obtained from agricultural waste.

And, while we’re on an environmentally-supportive roll, let’s hear it for a strain of bacteria that eats spilled oil.

It’s indigenous to the Galician shore of north-west Spain, and ironically may have developed its oil-loving tendencies because of past contamination in that area.

Then again, how about bacteria as an eco-friendly packaging material?

German designer Marika Frensememeier won a 2009 prize for her concept “Bacs”, a type of biodegradable packaging formed by coating an object with a culture containing Acetobacter xylinium, then feeding it with a sugary nutrient that causes the bacteria to develop into a “fibrous nano-scaled cellulose network.”

Bacteria also play a big part in fermentation.

While it’s yeast that is responsible for beer becoming alcoholic and for bread rising, a beer or bread’s taste is often dependent upon bacteria.

That’s certainly the case with sourdough bread.


A landmark study of sourdough in 1970 identified a bacterium in it that had never been found in nature before.

It was given the name Lactobacillus sanfranciscensis in recognition of San Francisco being the true, original home of sourdough.

(And of uBiome of course.)

Years ago it was said that it was impossible to bake sourdough bread that tasted truly authentic outside a 50 mile radius of San Francisco.

Meanwhile over in the brewery, bacteria are responsible for the distinctive alkaline taste of sour beers like Berliner weisse, with our old friend Lactobacillus once again doing a lot of the heavy lifting.

Human bacteria have also been used in cheesemaking, this time in the name of art.

American artist Christina Agapakis swabbed the hands, feet, noses, and armpits of volunteers, then used the collected bacteria to inoculate fresh organic milk that was incubated overnight.

She made cheese from the resulting curds, reportedly not for human consumption though.

A slice of sweat-dar on your sandwich, anyone?

But let’s end on a more serious note.

Scores of countries around the world are littered with undetonated landmines.

Many thousands lose limbs or lives as a result.

So we should pay big tribute to the scientists who have developed a bacteria-laden colorless solution which can be sprayed from the air onto the ground, turning bright green in the presence of explosives.

Now that’s one type of germ warfare I think we could all endorse.

Further reading

100% biocompatible self-constructing protective packaging

12 ways bacteria improve our lives

A hope for oil spill bioremediation

A new view of the tree of life

Christina Agapakis

Economic importance of bacteria

Glowing bugs could find landmines

Human cheese – only the first course for odd cheeses

Inositol phosphate

Microorganisms of the San Francisco sour dough bread process

The biology of sourdough

The tree of life just got a lot weirder

Using waste to recover waste uranium