DISCOVERED WORLD'S LARGEST BACTERIUM (Thiomargarita magnifica)

By definition, a microorganism or microbe is an organism of  microscopic size (they can only be seen with a microscope), which may exist as single celled form or as colonies.

But the newly described bacterium (Thiomargarita magnifica) living in Caribbean mangroves are different from known properties of microorganisms. Its threadlike single cell is visible to naked eye, growing up to 2 centimeters. This bacterium has a large genome which is not free floating inside the cell as in other bacteria, but instead encased in a membrane ( like the characteristics of complex cells).

Basically the living organisms can be divided into two broad categories: One is prokaryotes-which include bacteria and single celled organisms called Archaea and second is eukaryotes, which include either single celled or multicellular organisms that contain nucleus and other membrane bound organelles. There is a wide range of Eukaryotic organisms, including all animals, plants, fungi and protists. Prokaryotes are organisms that lacks a distinct nucleus and other organelles due to the absence of internal membranes. The newly described organism blurs the line between prokaryotes and eukaryotes.

Thiomargarita namebiensis was discoverd in Oceanic sediments off the Namibian coast in April 1997 and currently holds the world record for second largest bacterium. This microbe ranges from 100 to 300 micrometers in length with the largest reported to be 750 micrometers. In comparison, E.coli and other normal sized bacterium are an average of 2 micrometers, approximately 0.7% the size of Thimargarita namibiensis.

Like Thiomargarita namibiensis, found in Namibia, the new mangrove bacterium also has a huge sac presumably of water- that takes up 73% of its total volume. That similarity and a genetic analysis led the research team to place it in the same genus and propose calling it Thiomarita magnifica.

The genetic analysis with labelling the DNA with fluorescent tags shows the bacterial genome was so big because there are more than 500,000 copies of the same stretches of DNA. Ribosomes were also observed inside the DNA-filled sac.