|MadSci Network: Microbiology|
Distinguishing chemoautotrophs by morphology may be difficult as the physiology does not necessarily relate to the morphology. For instance there are chemoautotrophs in both the Gram positive and Gram negative classification scheme, and under the microscope their morphologies can be similar to certain heterotrophic bacteria. There is an exception with cyanobacterium (photoautotrophs). These bacteria have very distinct morphologies and have unique structures like heterocysts (nitrogen fixing cells). For images of their morphologies click here . It is easier and more conclusive to isolate and identify chemoautotrophs by using selective media rather than morphologies, (i.e. using a growth media with no organic carbon sources). Hope this helps.
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