SALT LAKE CITY--A strain of Pseudomonas bacteria appears to produce a compound that may help in the fight against zebra mussels, the pests that have infiltrated North American lakes and rivers by the billions. If successful, the research could lead to the first biological control system for the prolific invaders.
Native to Europe, zebra mussels were first detected in Lake St. Clair near Detroit in 1989. From there they have spread east, west, and south, and they're now found as far away as Louisiana. The mussels attach to almost any hard surface, causing millions in economic damage by clogging pipes at power plants and industrial facilities; they also put a damper on recreation by sticking to boats and washing up on shores by the ton after they die. Treating pipes with chlorine can help, but it is harmful to the environment.
Hoping to find a natural alternative, Daniel Molloy of the New York State Museum in Albany screened a large number of bacteria for anti-zebra-mussel activity. He found a strain of Pseudomonas fluoresecens isolated from a North American river that, at sufficient concentrations, kills the animals across the temperature range the mussels grow in, Molloy reported here yesterday at the general meeting of the American Society for Microbiology. Autopsies on the mussels showed that the so-called tubules in their digestive glands were heavily damaged; further tests revealed that even dead bacteria could do the job. That proves the bacteria work by producing a toxin, not by infecting the mussels, says Molloy. The next step is to identify the compound, which appears to be specific for zebra mussels--bacteria didn't harm several other freshwater species tested, including brown trout, blue mussels, and six other bivalve species.
There's still a way to go before the bacteria can be put to work, says Dewi Bakker, who studies how to control marine fouling on ships at the University of Groningen in the Netherlands. Bakker points out that the team needs "gigantic amounts" of the bacteria to kill zebra mussels, which would currently make growing the killer bugs expensive. But Molloy says if the toxin turns out to be a protein, it may be possible to clone the encoding gene and make yeast cells churn out the compound in greater quantities.
More about zebra mussels from the U.S. Geological survey
Daniel Molloy's home page