Festival Of Fungi: From Spongelike To Dishwasher-Hardy

What does a scientist do when faced with the task of naming a newly discovered, spongelike orange fungus from a tropical rain forest in Malaysia? Why, name it after the cartoon character SpongeBob SquarePants, of course.

At least, that’s what San Francisco State University biology professor Dennis E. Desjardin and colleagues did when they named their new discovery Spongiforma squarepantsii (Mycologia, DOI: 10.3852/10-433). Astute Newscripts readers may find Desjardin’s name familiar: He also discovered the bioluminescent fungus Mycena luxaeterna that made the list of top 10 new species discovered in 2010 (C&EN, June 13, page 48).

S. squarepantsii is shaped like spongy orange balls roughly 3–5 cm in diameter and has “a vaguely fruity-musty and pleasant odor,” as Desjardin and coauthors describe the species. Its reproductive spores look reddish brown in water but turn lilac gray when dosed with dilute potassium hydroxide. A number of oxidation reactions occur in fungi when they are subjected to bases such as potassium hydroxide or ammonium hydroxide, Desjardin says. “Some tissues turn yellow, red, purple, green, or blue. We do not know what these reactions are.”

The only other species known in the Spongiforma genus is S. thailandica and was discovered by Desjardin in a rain forest in Thailand. S. thailandica has a larger, more oblong spongy structure that starts out having a grayish orange or brownish gray color and darkens with age. Sadly, this one doesn’t have a pleasant odor: It smells like coal tar.

The fact that the two Spongiforma species were found in separate geographic areas suggests that more varieties might turn up in rain forests elsewhere, Desjardin says.

While Desjardin tromps through rain forests, other scientists look to extreme environments to discover new or unusual organisms. For example, alkaliphiles grow at high pH, halophiles require high salt concentrations, and thermophiles thrive at high temperatures. A polyextremophile might do all of the above.

But it turns out that we might not have to venture very far to find such organisms, reports a group led by Polona Zalar, a microbiologist at the University of Ljubljana, in Slovenia. Zalar and colleagues cultured swabs from the rubber seals of 189 dishwashers in 18 countries across six continents (Fungal Biol., DOI: 10.1016/j.­funbio.2011.04.007). Although dishwashers are supposed to eradicate micro­organisms rather than incubate them, the scientists found that 62% of the machines contained yeast, including several species that can cause infections in people with compromised immune systems.

One particularly interesting find was Magnusiomyces capitatus. “The natural habitat of this fungus is not known, as only two strains derived from heated woodpulp have been found in the environment,” the researchers write in the paper. “Our recurrent isolation of this fungus from dishwashers suggests that it has found a niche in the human-made environment of household machinery.”

Other species are remarkable for their properties. Two in particular, Exophiala dermatitidis and E. phaeomuriformis, grew in the lab at temperatures up to 47 °C, at pHs ranging from 2.5 to 12.5, and on media containing 17% salt. Scientists have not seen this combination of thermotolerance, pH tolerance, and halotolerance in fungi before, according to Zalar and colleagues.

Although the species found in the study are not a health risk for most people, that could change, the scientists warn. They found that different genotypes of E. dermatitidis and E. phaeomuriformis can coexist in the same dishwasher, raising the risk of genetic recombination to produce new pathogenic properties. More research into household habitats and their microbial communities is necessary, the scientists say.

Newscripts can always raise a (hopefully clean) glass to that.

Chemical & Engineering News

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Copyright © 2011 American Chemical Society