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Arch Microbiol (2012) 194:135140 DOI 10.1007/s00203-011-0755-0
SHORT COMMUNICATION
What is an autotroph?
Vijayasarathy Srinivasan Harold J. Morowitz
Harald Huber
Received: 24 July 2011 / Revised: 24 July 2011 / Accepted: 13 September 2011 / Published online: 30 September 2011 Springer-Verlag 2011
Abstract The concept of autotrophy depends on the growth media for pure cultures supplying a single one carbon source for anabolism. Secondary carbon compounds added to the medium as chelators and/or vitamins confuse the meaning. This note suggests a clarication of denition suitable for contemporary biochemical studies of true autotrophs.
Keywords Autotroph Absolute autotroph
Growth media Carbon xation Vitamin EDTA
Chelator Trace element Transition metal
Biogenesis
The concept of autotrophy goes back to Sergei Winogradskys work in the 1880s on a group of organisms that synthesized all their biochemicals with carbon dioxide as the sole carbon source (Winogradsky 1887, 1890). He
envisioned the existence of an ecological niche in which a group of microbes relied entirely on oxidation of inorganic sources for their energy and carbon dioxide as the singular input for carbon xation. Winogradsky designated these organisms as anorgoxydants meaning inorganic oxidizers (Winogradsky 1922). Extension of this pioneering work over the decades leads to two classes of autotrophs, depending on their energy sourcesphototrophs whose source is sunlight and chemotrophs that obtain their caloric input from inorganic redox couples and pyrophosphates in the environment (Starkey 1961). For this discussion, we will focus on Bacteria and Archaea and shall not consider the photosynthetic eukaryotes, plants and protists. A large literature is available on further subdivisions of autotrophic organisms under obligate autotrophy, facultative autotrophy, mixotrophy and strict autotrophy (Kelly 1971; Ehrlich 1978; Jordan et al. 1997; Padden et al. 1998; Kelly and Wood 2002; Wood et al. 2004; King 2007; Geelhoed et al. 2010). In bacteriology, autotrophy has become determined by the growth of a pure culture in a strictly inorganic growth media, devoid of any organic compounds other than carbon dioxide (or carbonate) that serve as the sole source of carbon (Starkey 1961). Subsequent studies have uncovered other one carbon autotrophs that use carbon monoxide (Sokolova et al. 2001a, b, 2007; Nakagawa and Takai 2008) carbon disulde (Smith and Kelly 1988; Henstra and Stams 2004), methane (Dedysh et al. 2004a, b; Islam et al....