Chattanooga Sludge
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by Molly Bang
Gulliver Greene/Harcourt Brace, 1996

Reviewed by David C. Holzman

Bacteria have certainly been making the news of late, what with speculation last summer that some meteorites of Martian origin found in Antarctica contained their footprints, followed by conjectures concerning potential prokaryotic habitation in Jupiter's fourth largest moon, Europa.

Maybe the timing of all this excitement, coinciding as it does with the publication of Molly Bang's wonderful children's book featuring bacteria, will at last give Earth's oldest inhabitants their due. After all, bacteria were here for several billion years before the first multicellular life slithered in the muck, and should nuclear holocaust or cosmic collision wipe out the rest of life on Earth, bacteria undoubtedly shall survive.

Bacteria are the ultimate recyclers of organic material, and they inhabit every conceivable niche on earth, from the hot "paint pots" of Yellowstone National Park to the perpetual darkness of hydrothermal vents deep beneath the surface of the ocean, to the nooks, crannies, and plumbing of our own bodies. Bacteria comprise one tenth of the weight of a Homo sapiens.

Lately evidence has begun accumulating that bacteria may live deep in the bowels of the Earth. From time to time, fractures open in the ocean floor and belch forth gases. The isotopic composition of the carbon in the gasses, and the observation that colonies of bacteria grow around such fractures - sometimes within days of an eruption - suggests that bacteria lie within.

All this led to the speculation that Europa, slightly smaller than our own moon, might harbor bacteria in an ocean of water that scientists surmise lies beneath a layer of ice estimated to be anywhere from two- thirds of a mile to more than 60 miles thick. NASA has just released photos taken February 20 by the space probe Galileo from 363 miles above Europa's surface, photos that show the unmistakable signature of icebergs breaking apart and regrouping, strong evidence that liquid - presumably water - is circulating beneath the ice. Here is habitable territory.

While the possibility of life on Europa and Mars tantalizes the public, most Americans remain ignorant of the preeminent role that bacteria play on our own planet and in our bodies. Small wonder. Most public school science teaching fails to excite the imagination. And it's hard for adults to learn to love bacteria. They're too subtle. They don't play basketball with Michael Jordan. They have yet to accuse a sitting president of wrongdoing. Oprah has never had a bacterium as a guest on her show. Nor has a prokaryote ever starred in one of Steven Speilberg's films. In fact, the only time people pay attention to microbes is when they are cast as villains, as in Laurie Garrett's The Coming Plague.

Here's a book that could change all that. Chattanooga Sludge, by Molly Bang, is the true story of one scientist's effort to clean up Chattanooga Creek.

The tale begins with scientists' discovery that Chattanooga Creek contains "large amounts of thirty-three poisons" and their declaration that it is "the most polluted waterway in the southeastern United States."

No one knows what to do about the problem. But "one day a member of the Chattanooga City Council read about a man from Massachusetts who had a peculiar idea about sewage. He said that our sewage is not a waste to get rid of but a precious resource we should save and use with care."

The man built greenhouses and filled them with tanks. He filled the tanks with tropical plants and marsh plants and flowering plants and vegetables and trees - and fish and snails. Then he fed the plants on sewage water. Gray, disgusting water went in one end of a greenhouse, fed the plants, and poured out pure and clean on the other side. The man called his greenhouses Living Machines because living plants and creatures did all the work of cleaning the water.

Could Living Machines clean up toxic sludge? The city councilors invite the man from Massachusetts to view their waterway. The man, who is cast thus in the text in order to appear as a scientific Everyman, but is identified as John Todd by the frog angels that populate the margins of the beautifully illustrated pages, doesn't know if his tanks can clear the poisons from the sludge. Plants, animals, and bacteria have always recycled sewage, but the toxins of Chattanooga Creek are relatively new to Earth, and we don't know if bacteria have yet evolved that can recycle them. But Todd will have a go. (Todd, the founder of the New Alchemy Institute in Falmouth, on Cape Cod, is quite accurately depicted in Bang's pictures with his deep blue eyes, round head with bald pate, and unruly flaxen hair.)

Quickly, it becomes clear that second to Todd, bacteria will be the protagonists of this story. "Some bacteria pull chemicals out of the earth or the air and rearrange them into new chemicals that plants and animals need in order to live. And bacteria can take apart almost all substances, breaking big molecules into smaller ones. Some bacteria take apart meat, some take apart bones. And some bacteria take apart toxins, like those in the sludge from Chattanooga Creek."

Quickly it becomes clear that second to Todd, bacteria will be the protagonists of this story. "Some bacteria pull chemicals out of the earth or the air and rearrange them into new chemicals that plants and animals need in order to live. And bacteria can take apart almost all substances, breaking big molecules into smaller ones. Some bacteria take apart meat, some take apart bones. And some bacteria take apart toxins, like those in the sludge from Chattanooga Creek."

As for Todd's living machine, we watch in suspense as the fish in the bioassay tank begin to die, indicating the continuing presence of toxins. But after a month the poisonous stink is gone, and the snails are laying eggs, a good sign. Todd sends the water off to a laboratory for testing.

Bang, an acclaimed author of several other (though nonscientific) children's books, breaks the rules. Most children's books are aimed at narrow age ranges. The format - big 8 x 11 pages with vivid illustrations on every page - could tantalize a toddler. But Bang doesn't bother to talk down to kids. The vocabulary is more sophisticated than that in your average magazine story. The author seems to know that if you capture children's imaginations, they will work to understand something that is partly over their heads.

Seven-year old Madeleine Nutting paid rapt attention as I read the book to her and her 11-year old sister, Halley (born the year of the comet). Halley grew somewhat restless during the story, which took 40 minutes to read, partly because Madeleine insisted on reading most of the frog angels' lines, but at the end she allowed that this was the best science book she'd ever read.

I also tried out the book on my 34-year-old sister, a stay-at-home mom and former purveyor of gourmet foods who was totally turned off from science in school, despite attendance at one of the best public high schools in the country. Her reaction: "I never knew bacteria were so important."

So give this book to your children. Or give it to an English major. When it comes to teaching bacteria to serve human needs, a little respect and a lot of understanding will go a long way.

David C. Holzman is a contributor to the Journal of the National Cancer Institute and the American Society for Microbiology News. His first article for Smithsonian appears in the June issue.

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