21 May 1998

Bacterial Minders For Sensitive Rocks

Far from contributing to the destruction of the natural environment, bacteria may be trying to hold things together in the face of human damage. A pair of scientists at Sam Houston State University investigating microbial communities on sandstone outcrops in the Colorado Plateau have shown that these organisms act to protect rock from the effects of wind and rain. Park managers are looking for ways to stabilize damaged areas - it may have been under their noses all along.

Harry Kurtz Jr. and Dennis Netoff conducted a series of experiments on the stone-dwelling microbes. They regenerated a microbial community in the laboratory by adding a sample of bacterial culture to crushed sandstone. "After extended incubation, growth of the bacterial communities became apparent due to the green coloration of the sand where the microbes were applied," said Kurtz. After drying and inspecting matured cultures it was found that "the presence of bacterial growth significantly hardened the sand surface.


When provided with water and nutrients the microbes produce acidic polysaccharides, starches very similar to high-school glue, which have the potential to bind metal ions. Kurtz and Netoff believe that spraying microbes in threatened areas with a water-based nutrient spray could encourage bacterial colonization and hardening of rocks' surfaces. This would offset the erosive process, often started by hikers and bikers in National Parks, which at present is leading authorities to restrict access.

Kurtz and Netoff have been intrigued by the Martian meteorite found in Antarctica and the Martian landscapes transmitted from the Pathfinder space probe. They would love to get their hands on rock samples from Mars one day, to test their theories further. But for now they're just over the moon with what their discovery could mean for endangered areas.