Philip Liebson
Chicago, Illinois, United States

As early as 1676, Dutch textile worker Anthony Van Leeuwenhoek, working with an early microscope, was the first to identify bacteria. Because of the size of bacteria, easily seen by a microscope, it was inevitable that bacteria would be discovered by someone.

Not so with viruses. Although the smallest bacteria are the sizes of the largest viruses, the latter are usually about a tenth of the diameter of bacteria. So it is not surprising that viruses were not first identified, if not actually observed, until the late nineteenth century by two microbiologists—Russian Dmitri Ivanovsky in 1892 and another Dutchman, Martinus Beijerinck.

Beijerinck, born in Amsterdam in 1851, achieved a Doctor of Science degree in 1877 from the University of Leiden and taught in a school of agriculture in Delft. His microbiological investigations involved agricultural diseases. In studies of tobacco mosaic disease, by means of filtration experiments, he postulated an organism that could not be cultured and was smaller than a bacterium, but was infectious and could replicate and multiply within the tobacco plant. In 1898 he published the results of his studies naming the organism a virus, to differentiate it from a bacterium. He could not observe the organism itself, thinking it was in liquid form. It was only in 1941 that the organism was finally observed to be a particle, demonstrated by X-ray crystallography.

His other studies included the process of nitrogen fixation by bacteria in legume plant roots to produce ammonium, which nourishes the soil, and the use of sulfate by bacteria for anaerobic metabolism. The latter investigation led to his early reputation since it determined that this bacterial process in yeast factory boilers led to a buildup of calcium sulfate befouling the water.

His professional career at Delft ended in 1921, when he was 70, and he died in 1931. He was an ascetic and never married, with a difficult temperament preventing him from relations with students and other faculty. Although his scientific reputation grew and he visited several important researchers in Europe, because of his reputation for dispute, the bacteriologist Robert Koch refused to meet him, and his research was mostly undertaken alone.

Further reading

• Chung, K.T.; Ferris, D.H. (1996). “Martinus Willem Beijerinck (1851–1931): Pioneer of General Microbiology” (PDF). ASM News. 62 (10). Washington, D.C.: American Society For Microbiology: 539–543. Archived from the original (PDF) on 25 April 2012.
• Bos, L. (29 March 1999). “Beijerinck’s Work on Tobacco Mosaic Virus: Historical Context and Legacy”. Philosophical Transactions: Biological Sciences. 354 (1383): 675–685. doi:10.1098/rstb.1999.0420. PMC 1692537. PMID 10212948.