Cover of The Microbial World: Foundation of the Biosphere
A revolution has occurred in microbiology, the ramifications of which are not yet widely known or appreciated, but which provides new opportunities for agriculture, medicine and industry. Using new techniques and approaches—in particular sequencing and analysis of ribosomal RNA genes— microbiologists have discovered that there are at least 20 major evolutionary groups of the microbial life forms on Earth—bacteria, fungi, algae and protozoa—that are even more diverse than the better known plant and animal kingdoms. Furthermore, recent evidence indicates that millions of microorganisms still remain to be discovered. These new microorganisms provide a vast untapped reservoir of genetic and metabolic diversity, the harvesting and study of which will have far-reaching, positive effects for society in areas such as enhanced food production, medicine (e.g., antibiotic discovery), bioremediation of waste materials and agriculture.

Part of the revolution in microbiology stems from development of methods that now make it possible to inventory the diversity of microbial life on Earth and to do so cost-effectively. The power of the new technologies on which these methods are based will reveal the extraordinary range of metabolic, physiological and evolutionary diversity of microbial life on Earth. Programs to harvest this bountiful, yet invisible, microbial diversity have already begun in Japan and Europe. The United States scientific community, largely responsible for creating the revolution, is uniquely positioned to mount a comprehensive effort that takes full advantage of newly evolving technologies. A microbial exploration and harvesting program to assess the variety and commercial potential of microbial life forms on Earth will reap great benefits for society. Furthermore, a microbial exploration and harvesting program employing existing and developing technology would launch a voyage of discovery and exploration that would quantify the diversity of microbial life forms on Earth and provide, at least in part, an answer to the question of how much microbial diversity has yet to be discovered. Current estimates, based on partial and random sampling, are certainly gross underestimates of the actual diversity of microbial life extant on Earth. An inventory would identify environments where the greatest diversity exists, and those areas can be productively targeted for more intensive exploration. Harvesting and study of novel microbial types will doubtless lead to the discovery of new biomaterials, development of new commercial processes and enterprises and acquisition of knowledge of practical importance to society.

To grasp the full extent of microbial diversity, iterative steps need to be taken. For example, sequencing the genome of at least 1 microbial species from each of the major phyla of microbial life can provide information about another type of diversity: the biochemical potential of microorganisms comprising each of the major groups. DNA sequence analyses of microbial genomes obtained to date have revealed an unanticipated richness of novel genes; this approach can be expected to identify completely novel processes and biochemical compounds that will find timely application in biotechnology and health care.

In order to delineate effectively the extent of microbial diversity and identify potential applications, several recommendations are made, addressing infrastructure necessary to ensure attainment of the goals, and include initiatives in education and training, instrumentation needs, establishment of regional and national research centers of excellence, development of databases and enhancement of genetic resources in culture collections.


James T. Staley, Richard W. Castenholz, Rita R. Colwell, John G. Holt, Matthew D. Kane, Norman R. Pace, Abigail A. Salyers, James M. Tiedje. 1997. The microbial world: foundation of the biosphere.

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