Giant Bacteria  

Until now we believed that the bacteria are tiny and can be seen only under microscope. However, marine biologist Jean-Marie Volland of the Laboratory for Research in Complex Systems in Menlo Park, California and his colleagues found an unusually large, sulfur-oxidizing bacterium with a complex membrane organization on the decaying mangrove leaves in the waters of a Caribbean mangrove swamp. Named Thiomargarita magnifica, the giant bacterium measures one centimeter in length and is visible to the naked eye. Using fluorescence, x-ray, and electron microscopy in conjunction with genome sequencing, the team characterized and observed highly polyploid cells with DNA and ribosomes compartmentalized within membranes.

The DNA, instead of floating freely inside the cell as happens in other bacteria, is compartmentalized within membrane-bound structures, as seen in eukaryotes – a group of organisms that includes plants and animals. These are first discovered while collecting water samples in tropical marine mangrove forests in the Caribbean’s Lesser Antilles. The long white filament like structures suggested them to be some eukaryotes at first instance. However, the genetic analyses showed that the organisms were actually bacteria. This new discovery has opened up new way of thinking about bacteria.

Dr. Anand R
Senior Scientific Officer, KSTA