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Curriculum Development > High School 9-12 > Other Supplemental Programs > Frontiers in Microbiology > Introduction

Frontiers in Microbiology - I. Introduction

Our planet contains creatures that “breathe” metals and can survive extreme temperatures, pH, salinity, and dehydration. By almost any measure, microbes are vital to the health of the earth. They had been evolving for nearly 3 billion years before the emergence of the first visible organisms. It is the microbes that generated the earth’s geochemical cycles and today they maintain the oxygen in our atmosphere.

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Despite their importance, microbes are second class citizens in biology’s hierarchy. We tend not to notice microbes unless they can help us, as in the process of fermentation, or hurt us, as in the case of pathogenic species. This explains why many advances in microbiology are associated not with basic research but with industry or healthcare. The rest of the time microbes are easy to overlook; out of sight, out of mind. Recent progress in microbiology however, challenges us to overcome our bias against the invisible.

The Human Genome Project (HGP) spurred the development of high-throughput DNA sequencing. In 1995 the first genome of a free-living organism, the bacterium Haemophilus influenzae, was sequenced. Eleven years later, more than 300 completed microbial genomes are available and nearly twice that number are in progress. Analyses of these genomes are changing our concept of the tree of life and expanding our view of where life can be found. A phylogenetic tree based on molecular data reveals that plants and animals occupy but a couple of twigs on the branch labeled "Eukarya."

Techniques such as whole-genome shotgun sequencing enable researchers to investigate microbial diversity without the need to grow thousands of different species in the laboratory. A recent study by Craig Venter and coworkers (Venter et al., 2004) sampled the waters of the Sargasso Sea. Even though this part of the Atlantic Ocean is nutrient poor, Venter's group found abundant microbial life. Using whole-genome shotgun sequencing they sequenced DNA from at least 1,800 different species, including 148 putative new species. They also sequenced more than 1.2 million new genes. Such an approach holds great promise for exploring the largely unknown boundaries of microbial diversity.

High school biology classes convey very little of the revolution occurring in microbiology. The vast majority of high school textbooks treat microbes as they did a generation ago. Students learn the anatomy of bacteria; they learn how bacterial cells differ from the cells of plants and animals. Little new information about the origins, ubiquity, diverse metabolisms, life in communities, and environmental impacts of microbes is included. At the same time, textbooks stress the diseases caused by a small minority of microbial species. In the context of biotechnology, bacteria are mentioned as useful for cloning genes but they are not discussed as subjects worthy of study in their own right. Students do not appreciate why governments and biotechnology companies are investing huge sums of money to understand how microbes function and affect our health and environment.

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