Microorganisms

[Stevie1630]

What is included in the category of microorganism?
Anyone know if the nematode C.elegans is a microorganism?
Thank you

[theprof]

A microorganism may be defined as an organism of microscopic or submicroscopic size.

In turn, the terms microscopic and submicroscopic refer to any organism not visible to the naked eye ie organisms that are only visible with the aid of a light or electron microscope. Typical examples include bacteria, protozoans, algae, viruses, fungi and yeasts as well as members of the Nematoda.

Mature Caenorhabditis elegans are around 1mm long and although they are often treated as microorganisms in the lab in culture dishes, they are just about visible to the naked eye. Therefore, they are not strictly a microorganism. However, it's debatable as many workers claim that because they are barely visible, they should be classified as a microorganism.

The reality is that there is no right or wrong answer to the question. I looked at a colony of them a few months ago and I could just about see them without my specs. On the other hand, the lab technician had to put the petri dish on the stage of an low-power inverted brightfield microscope before she could see them although a hand-lens would also have done the trick.

As you know, C.elegans was the first animal to have its complete genome sequenced.

[Clanad]

The simplest definition of a microorganism is one that requires a microscope to view them. Although the upward limit is usually considered to be about 0.2mm, the nematode Caenorhabditis elegans is approxiamtely 1mm in length at maturity, but the egg and larvae stages are, obviously, much smaller and require study with the use of a microscope...

[Clanad]

Excuse the duplication theprof, since there were no postings when I began...

[theprof]

No problem Clanad. These things are bound to happen now and again.