Over one hundred years ago Robert Koch made one of the most important conceptual and technological breakthroughs in the history of microbiology with the discovery of methods for the production of solid nutrient media and the ability to isolate pure cultures of microorganisms.
The importance of this discovery to advances in medical, agricultural and industrial microbiology would be hard to overestimate. The dividends these techniques returned have positively affected the lives of nearly everyone on the planet. The training of generations of microbiologists has been based, to a significant degree, on the investigation of the properties of pure cultures and the elucidation of the properties of these organisms one at a time. As productive as this strategy has been it perpetuates an astonishingly erroneous conception. In fact, pure cultures are absent or virtually so in nature. Photo Courtesy of
the National Library of Medicine. This suggests that most of what we know about microorganisms has been learned under conditions that exist nowhere outside of a laboratory.
Microorganisms, like other organisms, exist in assemblages or communities in which interactions of a variety of sorts exist. Mutualism, commensalism, antagonism, and saprophytism are but a few of the more common interactions known to exist among microorganisms and between microorganisms and multicellular organisms. Given the number of known microbes and the estimated number of those yet to be discovered the complexity of the interactions in nature can be described without hyperbole as astronomical.
Original drawings by Rober Koch of Bacillus anthracis.