Which is smallest micro organism present?

Answer 1

The site listed below says that prions are the smallest microorganism. However, there is some disagreement about the status of viruses and other particles that aren't made of cells.

http://www.eh.uc.edu/superfund/oerther.pdf

Answer 2

The smallest organism found on Earth can be measured using a variety of different methods, and can be defined as the smallest by volume, mass, height, or length. Because there is some dispute over what the definition of life is and what entities qualify as organisms, the actual "smallest organism" (microorganisms) may be unclear.
I think the smallest could be this:
Nanobes are thought by some to be the smallest known organism, about ten times smaller than the smallest known bacteria. Nobes, tiny filamental structures first found in some rocks and sediments, were first described in 1996 by Philipa Uwins of the University of Queensland. The smallest are 20 nm long. Some researchers believe them to be merely crystal growths, but a purported find of DNA in nanobe samples may prove otherwise. They are similar to the life-like structures found in ALH84001, the famous Mars meteorite from the Antarctic.

Answer 3

Assuming you mean free-living organisms, not prions or viruses, that live using the machinery of other cells, bacteria are the smallest microbes.
The smallest known bacteria that have been clearly described belong to the type called phytoplasma, which infect plants much as the mycoplasmas infect animals. Haemophilus influenzae, that was once thought to cause influenza, is among the smallest bacteria: 0.2–0.3 by 0.5–2.0 micrometers, which is about the smallest object that can be seen through a light microscope. Many bacteriology textbooks say Mycoplasma genitalium is the smallest known organism capable of independent growth and reproduction. Its size is given as 0.2 to 0.3 µm (micrometers). The marine ultramicrobacteria, Shingomonas sp strain RB2256, has been reported to be able to pass through a 0.22 µm ultrafilter. It should be noted that many bacteria, in response to starvation, go to a dormant state of much smaller size. It is not clear how many of these "ultramicrobacteria" represent nutrient downsized bacteria.
In the early 1990’s scientists using an electron microscope observed 0.05 µm (50 nanometers) "nanobacteria" in rocks from hot springs. Nanobacteria were later found in blood, kidney stones, and in meteorites that came from Mars. Of course, this created quite a stir. But other researchers have not been able to find DNA or protein in nanobacteria, and it may be that the objects seen in the electron microscope are mineral microcrystals. Because of this, many experts doubt the existence of nanobacteria (see Nature (2000) 408, p394). However, supporters continue looking for evidence that nanobacteria are living.
A theoretical discussion of what could be the smallest bacterium possible gives a diameter of 0.17 µm http://www7.nationalacademies.org/ssb/nanopanel1.html. This figure also precludes the possibility of nanobacteria. The nanopanel web site has an excellent series of articles on the size limits of organisms.

Answer 4

The smallest organism found on Earth can be measured using a variety of different methods, and can be defined as the smallest by volume, mass, height, or length. Because there is some dispute over what the definition of life is and what entities qualify as organisms, the actual "smallest organism" (microorganisms) may be unclear.

The majority of biologists consider viruses to be non-living because they lack a cellular structure and cannot metabolize by themselves, requiring a host cell to replicate and synthesise new products. A minority of scientists hold that because viruses do have genetic material they can be considered as organisms. The smallest RNA viruses in terms of genome size are small retroviruses such as rous sarcoma virus with genomes of 3.5 kb and particle diameters of 80 nm. The smallest DNA viruses are the hepadnaviruses such as Hepatitis B, at 3.2 kb and 42 nm; parvoviruses have smaller capsids, at 18-26 nm, but larger genomes, at 5 kb. The smallest DNA bacteriophage is the Phi-X174 phage, thought to be larger than Hepatitis B, at about 4 kb.

Nanobes are thought by some to be the smallest known organism, about ten times smaller than the smallest known bacteria. Nobes, tiny filamental structures first found in some rocks and sediments, were first described in 1996 by Philipa Uwins of the University of Queensland. The smallest are 20 nm long. Some researchers believe them to be merely crystal growths, but a purported find of DNA in nanobe samples may prove otherwise. They are similar to the life-like structures found in ALH84001, the famous Mars meteorite from the Antarctic.

Nanoarchaeum equitans is a species of tiny microbe discovered in 2002 in a hydrothermal vent off the coast of Iceland by Karl Stetter. A thermophile that grows in near-boiling temperatures, Nanoarchaeum appears to be an obligatory symbiont on the archaeon Ignicoccus; it must be in contact with the host organism to survive. Its cells are only 400 nm in diameter, making it the smallest known living organism, excepting possibly nanobes, if the latter is considered to be living. Its genome is only 490,885 nucleotides long; as of 2005 it remains the smallest non-viral genome ever sequenced.


Mycoplasma genitalium, a parasitic bacterium which lives in the primate genital and respiratory tracts, is thought to be the smallest known organism capable of independent growth and reproduction. With a size of 0.2 to 0.3 µm (micrometers), M. genitalium is an ultramicrobacteria smaller than other small bacteria, including rickettsia and chlamydia. However, the vast majority of bacterial strains have not been studied, and the marine ultramicrobacteria Sphingomonas sp strain RB2256 is reported to have passed through 0.22 µm ultrafilter. A complicating factor is nutrient-downsized bacteria, bacteria that become much smaller due to lack of available nutrients.

Answer 5

A microorganism, by definition, is too small to be seen with the naked eye, so no. What you have here is a hypothesis. It's a silly hypothesis, but it is a hypothesis. If you expect anyone to believe your hypothesis, you need to do experiments to test it, and collect data supporting it. This is how science works. For instance, you could find these microorganisms under the microscope and transfer them into, say, rabbits, and see if rabbits suddenly become intelligent. This would be good evidence supporting your hypothesis. But so far, no such evidence exists, so everyone is going to laugh at you, and rightfully so. Extraordinary claims require extraordinarily strong evidence.

Answer 6

Nanobes are considered to be the smallest microorganisms present on the earth.

Answer 7

ok as u told microoranism virus is aslo included and the smallest is picorna virus [polio mylytis]
if bacteria its mycoplasmas

Answer 8

Virus

Answer 9

AT: http://www.euro.who.int/document/e79822.pdf

Answer 10

Nanoarchaeota. It measures 400NM.