The Importance of Being Blue

By MICHAEL D. LEMONICK

* It has been a year of dramatic progress and turbulence for scientists experimenting for the first time outside the lab with genetically engineered bacteria. This past April, California scientists made the first outdoor tests of ice-minus, a bacterium genetically altered to retard frost formation on leaves. Only four months later, Montana State University Professor Gary Strobel created a national outcry when it became known that he had flouted strict federal regulations by failing to get approval before injecting elm trees with bacteria designed to combat Dutch elm disease. This week Clemson University scientists, mindful of public fears about the escape of dangerous microbes, will begin a potentially revolutionary, 18-month test of special blue bacteria that have been modified so that researchers can readily detect their presence in the environment.

If all goes according to plan, a team of Clemson researchers at the school's agricultural research station near Blackville, S.C., will sprinkle a murky white liquid teeming with billions of Pseudomonas fluorescens bacteria on winter wheat seeds during planting. It should be easy enough to tell whether the invisible microorganisms survive and spread: the Pseudomonas bacteria have been altered by genetic engineers to turn a brilliant shade of blue in the presence of a compound called X-Gal. Declares Benton Box, dean of Clemson's College of Forest and Recreation Resources: "The potential we now have for tracking a genetically altered organism in the soil offers a tremendous opportunity. I think this is going to be a breakthrough." Says Jane Rissler, of the Environmental Protection Agency's office of toxic substances: "Unlike larger organisms, which can be tracked visually, these microorganisms are simply very small. The public has a right to know where they are."

Strobel's unauthorized action, which earned him a slap on the wrist from the EPA and Montana State, as well as the disapproval of most U.S. scientists, was not in itself dangerous -- federal officials and researchers alike agree on that. But by sidestepping the arduous regulatory process, Strobel fanned the fears of those who think genetically altered bugs might behave unpredictably in the wild, setting off an ecological catastrophe or disrupting local ecosystems. Most scientists consider the public's fears exaggerated, but they nonetheless acknowledge the need for caution. Says David Drahos, a senior research group leader at Monsanto, the giant chemical maker that is sponsoring the Clemson test: "We are all in the process of learning something very new and wanting to do it wisely and carefully."

Indeed, the experiment represents an attempt by Monsanto to accommodate regulatory guidelines that many scientists think are too strict. It is also aimed at mollifying public fears. Monsanto had originally planned to test a strain of Pseudomonas altered to produce a natural insecticide. The EPA nixed the field test, mainly because its formal evaluation was incomplete. Still, worried residents living near the Missouri test site protested loudly.

Monsanto scientists responded by changing the site to South Carolina and reformulating their strategy. Instead of using bacteria with the insecticide- producing gene, the company applied to release a strain engineered only to produce enzymes that enable it to digest lactose and X-Gal. Researchers could then detect the presence of migrating bacteria by dropping soil samples onto the lactose-based, X-Gal-laced growth medium.

The EPA agreed to the new test, primarily because of the innovative mechanisms for tracking the bacteria. In addition to turning blue, the bugs have been engineered to resist the antibiotic rifampicin -- a combination of properties that makes it possible to detect the presence of a single Pseudomonas among the billion or so microorganisms that may exist in a thimbleful of soil. Explains Margaret Mellon, manager of the National Wildlife Federation's biotechnology project: "This system is an important advance. In and of itself, it doesn't answer questions about whether bioengineered organisms are in general more or less safe than their natural counterparts. But it allows you to answer some of the questions. The marker system puts a little identity tag on the organism."

Indeed, the ability to track recombinant bacteria through the environment has become a crucial factor in getting EPA approval for a release. The lack of an effective marker has, for example, held up a test by Biotechnica International, a Cambridge, Mass., firm, of Rhizobium bacteria altered to boost their ability to fix nitrogen in the soil. In one of the California ice- minus tests, however, scientists have been able to monitor the spread of anti- icing bacteria on potato plants. The marker system in this case was rifampicin resistance, less sensitive than Monsanto's multiple indicator but still able to detect the presence of as few as 100 bacteria in a handful of leaves. The bacteria were successful as well as trackable: ice-minus appears to reduce frost damage early in the growing season by up to 80%.

Another of the regulators' concerns is the potential for spontaneous transfer of genetic material from an engineered organism to a natural one. Lab and greenhouse tests of Monsanto's blue bacteria indicate that the transferred genes have been stably inserted and do not readily migrate to other bugs. The same tests will now be repeated in the field -- and again, the results will be carefully tracked to see whether the bacteria survive and whether they spread into the environment.

As tracking techniques continue to improve, regulators may allow more field tests of genetically altered organisms. Few scientists expect a repeat of Strobel's iconoclastic behavior. Says Nickolas Panopoulos, a University of California, Berkeley, plant pathologist: "I don't think anyone would risk his career, bad publicity and maybe no grants for years to do it. And I would hope there won't be more unregulated releases, because it creates a bad impression."

Public relations aside, there are sound scientific reasons to proceed with caution. Says University of Minnesota Microbiologist Richard Hanson: "The release of bioengineered organisms is something new. You can get very strong arguments, from people who believe the hazards are great to people who believe there is absolutely no hazard at all. It's simply very, very difficult to judge the safety of such releases without having more data. It's important to get on with these experiments under carefully controlled and approved conditions." Monsanto's blue bugs should make those conditions easier to come by.

With reporting by J. Madeleine Nash/St. Louis