Nostoc commune: icky gross slime, or emerald carpet?
Today John, George, and the Florida Association of Environmental Professionals Treasure Coast Chapter combed the wet regions of Jonathan Dickinson State Park for grassy plants. About a million species to enjoy. The pine woods vistas and wildflowers were gripping as always. Blue Curls were at their best.
Now look on the ground below that fetching wildflower, there’s something even better. What grabbed me with the most gusto today were waves of green jello on the otherwise bare scrubby soil. We’re talking about huge bacterial colonies of the blue green bacterium (cyanobacterium) Nostoc commune. Some observers erroneously call these blue-green “algae.” And some get upset when the “algae” befoul their pristine lawn of pride.
This is one mighty germ. It is photosynthetic growing in microscopic strings of cells in colonies as big as dinnerplates. This species fixes nitrogen in special air-tight cells called heterocysts, seen as the larger light-colored cells in this photo link microscope view.
When you transform atmospheric nitrogen gas into forms plants can use, that’s fixed nitrogen. Legumes and some other plants do it with the assistance of certain bacteria. The symbiotic bacterial helpers in some cases, such as in Cycads, are species of Nostoc. Nostoc is the “algal” partner in some lichens as well, but today you have Nostoc living proudly off the leash. If this nitrogen-fixing mat isn’t nitrogenizing the hungry scrub sand I’ll be a monkey’s uncle!
You could walk through the scrub for years in dry weather and never spy Nostoc, except maybe as an inconspicuous dry crust we crush while seeking interesting things. This organism can dry out to a mere nothing for months, probably many years, and eventually bust out into its idea of glory when wet and ready. Then dry times resume and bye bye for now.
The world is full of odd symbioses, and Nostocs (including today’s species? perhaps not) have an unusual relationship with a tiny midge prone to lay its eggs in the Nostoc jelly for a safe haven and nourishment. What the fly offers the Nostoc is odd, if not adequately studied: the larva seems to induce changes in colony shape with an enhanced grip on its substrate and probable enhanced photosynthetic production. If I had nothing else to do, I could happily spend tomorrow searching for the larvae before the present Nostoc patches go back into hiding. Want to go play golf tomorrow? No thanks, I’d rather look for maggots in bacterial slime blobs.
Nostoc commune and related species are global and like arid places. They tolerate blistering heat, arctic freezing, blazing sun, and extended drought. No surprise they prompt research to probe the molecular biology behind happy life in extreme environments. Nostocs make so much fatty gel they’ve raised the eyebrows of biofuelophiles. They are so responsive to wet-dry cycles they cause research on environmental gene control. Nostoc reacts to extreme sun exposure with a UV-screen not known in any other living thing.
That UV protection is perhaps linked to an example of why we don’t eat the weeds, even if other people do. A recent article in the Journal of Ethnophamacology described the traditional consumption of Nostoc commune in Peru. Yummy good–but the fly in the ointment is a neurotoxic amino acid possibly linked to neurodegenerative disease. There’s always something.
Maybe it is no surprise how these close relatives of the oldest fossils known on earth survive nasty conditions perhaps resembling the primitive Earth when cyanobacteria ruled. Back when we were an almost-uninhabited planet. Like Mars.
Hmmmm, too bad Mars is so dry these days. Maybe a little green Martian Nostoc would come forth with a good honest wetting.