WE live as guests in a world dominated by microbes. They provide about half of the oxygen we breathe, are the basis for the food web that is essential to all higher species, and help balance the delicate global environment that has sustained our planet for almost 4 billion years.
Microbes were discovered only about 300 years ago-relatively recently. Antoni van Leeuwenhoek, a Dutch merchant, made microscopes with high-quality lenses that made it possible to observe microbes. He was the first to see microscopic living systems in blood, skin, plants, and pond water. But it wasn't until the 20th century that we began to appreciate the role of microbes in maintaining the health of our ecosystem.
Many microorganisms, such as Prochlorococcus marinus, are good. The P. marinus bacterium is the primary biomass producer in 75 percent of the world's oceans and is the smallest, most abundant photosynthetic organism. It is said to be equivalent in mass to all humans on our planet. DOE's Joint Genome Institute is currently completing the DNA sequence of this organism.
Other examples of "good" microorganisms are those used in industrial processes, including paper making, leather tanning, food processing, and alcohol fermenting. Others are found in products like laundry detergent, cheese, and yogurt. Some bacteria are responsible for keeping us healthy. These include the bacteria in our intestines that assist digestion and make essential B vitamins, or bacteria that can be made into vaccines to ward off other microbes.
"Bad" microbes are usually associated with human disease and are called pathogens; they have been responsible for many of the world's major diseases. Yersinia pestis is a bacterium that causes plague. Although relatively rare in the U.S., plague was responsible for the death of nearly one-third of the European population in the 14th century and is still a problem today in some developing countries. Another microbe, the influenza virus, killed more than 20 million people worldwide in 1918-1919, more deaths than occurred in World War I.
Bad microbes not only infect humans but also can attack crops, wildlife, and farm animals. They could cause major agricultural losses or lead to infection of people through contact or ingestion.
Microbes get ugly in at least two ways. First, some microbes are known to mutate (change) the sequence of their DNA quite rapidly. Mutation has the consequence of making vaccines and other treatment regimes less effective, such as those for AIDS, influenza, and hepatitis. Second, microbes can be abused for the purpose of bioterrorism. History shows that biowarfare has existed since the time of the Romans and remains a threat today.
The plethora of microorganisms, both good and bad, leaves one in awe of their genetic diversity, of the roles they play in maintaining our ecosystem, and of the elaborate but utilitarian machinery that has evolved over billions of years to allow them to maintain their niche in life. From the metabolic pathways that regulate the utilization of carbon to the biochemical pathways that precisely control the mechanisms of infection, these organisms deserve our respect.
Lawrence Livermore scientists are increasing their emphasis on microbial research. As members of the Joint Genome Institute, we are sequencing the DNA of several microbes important for carbon sequestration, nitrogen fixation, and bioremediation. In addition, as part of our national security role, we are focusing on those microbes that could be used in bioterrorism. With support from the Department of Energy and with partners at Los Alamos and the Centers for Disease Control and Prevention, we are using our expertise in molecular biology and biotechnology to sequence selected pathogens and develop the molecular tools to detect them. We are now beginning to unravel the mechanisms by which these pathogens become infectious in host systems. The article entitled Uncovering Bioterrorism illustrates some of the technologies and results of this work.

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