Sergei Nikolaievich Winogradsky (Ukrainian: Сергій Миколайович Виноградський, Russian: Сергей Николаевич Виноградский) (September 14, 1856 - February 25, 1953) was a Ukrainian - Russian microbiologist, ecologist and soil scientist who pioneered the cycle of life concept. He discovered the first known form of lithotrophy during his research with Beggiatoa in 1887. He reported in Winogradsky S (1887) "Über Schwefelbakterien". Bot. Zeitung (45): 489 – 610 that Beggiatoa oxidized hydrogen sulfide (H₂S) as an energy source and formed intracellular sulfur droplets. This research provided the first example of lithotrophy, but not autotrophy. His research on nitrifying bacteria would report the first known form of chemoautotrophy, showing how a lithotroph fixes carbon dioxide (CO₂) to make organic compounds.

Winogradsky was born in Kiev, in what was then the Russian Empire, and entered the Imperial Conservatoire of Music in St Petersburg in 1875 to study piano. However, after two years of music training, he entered the University of Saint Petersburg in 1877 to study chemistry under Nikolai Menshchutkin and botany under Andrei Sergeevich Famintzin. He took a diploma in 1881 and stayed at the University of St Petersburg to receive a degree of master of science in botany in 1884. In 1885, he began work at the University of Strasbourg under the renowned botanist Anton de Bary; Winogradsky became renowned for his work on sulfur bacteria. In 1888, he relocated to Zurich, where he began investigation into the process of nitrification, identifying the genera Nitrosomonas and Nitrosococcus, which oxidizes ammonium to nitrite, and Nitrobacter, which oxidizes nitrite to nitrate. He returned to St. Petersburg for the period 1891 - 1905 and there was chief of the division of general microbiology of the Institute of Experimental Medicine; during this period, he identified the obligate anaerobe Clostridium pasteurianum, which is capable of fixing atmospheric nitrogen. In 1901, he was elected honorary member of the Moscow Society of Natural Science and, in 1902, corresponding member of the French Academy of Sciences. He retired from active scientific work in 1905, dividing his time between his private estate and Switzerland. In 1922, he accepted an invitation to head the division of agricultural bacteriology at the Pasteur Institute at an experimental station at Brie - Comte - Robert, France, about 30 km from Paris. In this period, he worked on a number of topics, among them iron bacteria, nitrifying bacteria, nitrogen fixation by Azotobacter, cellulose - decomposing bacteria, and culture methods for soil microorganisms. Winogradsky retired from active life in 1940 and died in Brie - Comte - Robert.

Winogradsky is best known for discovering chemoautotrophy, which soon became popularly known as chemosynthesis, the process by which organisms derive energy from a number of different inorganic compounds and obtain carbon in the form of carbon dioxide. Previously, it was believed that autotrophs obtained their energy solely from light, not from reactions of inorganic compounds. With the discovery of organisms that oxidized inorganic compounds such as hydrogen sulfide and ammonium as energy sources, autotrophs could be divided into two groups: photoautotrophs and chemoautotrophs. Winogradsky was one of the first researchers to attempt to understand microorganisms outside of the medical context, making him among the first students of microbial ecology and environmental microbiology. The Winogradsky column remains an important display of chemoautotrophy and microbial ecology, demonstrated in microbiology lectures around the world.