The Dutch microbiologist/biochemist Albert Jan Kluyver was an early proponent of the idea of biochemical unity, and how that concept might be demonstrated through the careful study of microbial life. The fundamental relatedness of living systems is an obvious correlate of the theory of evolution, and modern attempts to construct phylogenetic schemes support this relatedness through comparison of genomes. The approach of Kluyver and his scientific descendants predated the tools of modern molecular biology by decades. Kluyver himself is poorly recognized (...) today, yet his influence at the time was profound. Through lens of today however, it has been argued that the focus by Kluyver and others to create taxonomic and phylogenetic schemes using morphology and biochemistry distorted and hindered progress of the discipline of microbiology, because of a perception that the older approaches focused too much on a reductionist worldview. This essay argues that in contrast the careful characterization of fundamental microbial metabolism and physiology by Kluyver made many of the advances of the latter part of the twentieth century possible, by offering a framework which in many respects anticipated our current view of phylogeny, and by directly and indirectly training a generation of scientists who became leaders in the explosive growth of biotechnology. (shrink)