From Elephant to Bacterium: Microbial Culture Techniques and Chemical Orders of Nature, 1875 – 1946

Abstract

This dissertation is a history of how microbial culture techniques reframed nature’s order in chemical terms. In the final decades of the nineteenth century, scientific workers developed techniques to study diseases and control fermentations, making chemical activities of microorganisms appreciable to human observers. Microbiologists across Western Europe and North America were fascinated by these transformations of matter and the implications they had for problems of agricultural, industrial, medical, and scientific interest. An exchange of cultures, substrates, data, and concepts ushered in novel relations between humans and microorganisms, including, most spectacularly, the use of microorganisms as models of entities and processes believed ubiquitous in living things. In its depiction of a transnational cohort of researchers and the organisms they cultured, the dissertation covers a period beginning in the late nineteenth century, as techniques of “enrichment” and “pure” cultures were adopted by growing numbers of microbiologists. Tracing uses of these techniques through the mid-twentieth century, the dissertation illustrates how chemical knowledge of microbial nutrition and metabolism sparked a proliferation of conceptions of nature’s order.

Chapter 1 looks at members of the “Delft School” of microbiology, who adopted cultures as instruments of chemical analysis and attempted to reform microbial taxonomy along chemical lines. Chapter 2 focuses on the work of Ernst Georg Pringsheim in isolating and maintaining a collection of pure algal cultures used to tease apart biological associations in muddy environs. Chapter 3 follows protozoologists André Lwoff and Marguerite Lwoff as they studied the nutritional needs of blood parasites, theorizing the evolutionary origins of parasitism. Chapter 4 turns to Edward Lawrie Tatum’s efforts to identify “growth factors” that microbes required, which were subsequently repurposed to isolate “biochemical mutants.” A concluding epigraph foregrounds the multiplicity of nature’s chemical orders, while exploring consequences that uses of culture techniques have had for biologists’ conceptions of life.

These case studies show how microbial cultures made chemical orders of nature legible by replacing ecological niches with conditions of human design. Such work helped substantiate ontological categories that remain central to how life is defined and understood, even as biologists have frequently noted limitations of their ordering schemata.