Thiomargarita Magnifica
In 2022, within the mangrove forest of Guadeloupe, a Caribbean island, the world's largest bacterium was discovered. Thiomargarita magnifica is over a centimetre in length, visible to the naked eye. This bacterium is approximately the size of the average eyelash, easily capable of being picked up with tweezers, and over 5000 times the size of the surrounding microscopic bacterium. This unique discovery has rethought the boundaries of unicellular life and flushed a wave of shock throughout the field of biological science.
Previously, this record was held by a giant sulfur bacterium discovered in the Shelf Sediments of Nambia. However, T. magnifica has conquered this score by over 10 times.
Dr Jean-Marie Volland, lead author of a paper surrounding this titan bacteria states how 'most bacterial cells are microscopic, and measure around two thousandths of a millimetre in length.' This shows how this discovery is restructuring microbiology as we know it, and 'while there are some exceptionally sized bacteria which can measure several hundred micrometres, these remain within the theoretical limit of how large these organisms can grow. T. magnifica, however, is significantly above this limit. When compared to most bacteria, it would be like a human encountering another human as tall as Mount Everest.'
How does it get so large?
Since most prokaryotes tend to be microscopic, they can rely on diffusion to transport material for respiration and other molecular processes. However, diffusion is only effective over microscopic distances, which limits the size to which prokaryotes can grow, so how has T. magnifica overcome this limitation? Well, this is done the same way as algae. Algae is the largest unicellular eukaryote, with some cells growing up to 30 centimetres in diameter, and what do Algae and T. magnifica have in common? They both live and grow in marine environments rich with minerals and organic matter. T. magnifica accumaltes on surfaces and decays all these nurtients, producing sulphide and growing their internal structure. This is due to T. magnifica being a sulphide oxidising bacteria.
Why is it so unique?
Whats also interesting about this bacterium is its complexity. T. magnifica has an interesting method of storing DNA. In the majority of other microbes, DNA floats freely within the cell's cytoplasm, however, T. magnifica stores it's DNA in membrane bound compartments, similar to how animal and plant cells store their DNA in nuclei. Scientists have decided to name these organelles 'Pepins', conveying how organisms containing pepins remain prokaryotic.