Chemotrophs

Chemotrophs

	Chemotrophs -Chemolithotrophs are organisms which can obtain energy by the oxidation of inorganic compounds. They are generally defined by their ability to grow in mineral media, and to derive their cell carbon from CO2. Many chemolithotrophs are commonly referred to as autotrophs.
This usage is valid if the definition of Woods and Lascelles (1954) is followed, i. e. autotrophs are organisms which can use CO2-as their major source of carbon. Autotrophic bacteria which cannot grow in organic media have been called obligate autotrophs. Rittenburg (1969, 72), however, contends that absolute dependence on CO2 based carbon metabolism does not exist. These bacteria can obtain at least some carbon from other sources. If a mixture of suitable organic acids is available, bacteria may even dispense with CO2 as the major source of carbon.
Rittenburg therefore advocated the use of the term, 'obligate chemolithotrophs instead of 'obligate autotroph, Matin (1978), however, states that the dependence of bacteria on CO2 for most of their carbon is obligatory, as they are on a lithotrophic energy source.
No organic compounds can replace CO2 as the major carbon source. He therefore advocates the term chemo litho--autotroph or obligate chemolithotrophs for these bacteria.