幾厘米長的T. magnifica並不是地球上最大的單細胞生物體。那可能是一種叫做Caulerpa taxifolia的水生藻類，它仍然是10倍長。但是當你考慮到地球上有許多複雜得多的生命形式需要某种放大鏡來觀察時，這種細菌絕對令人印象深刻。想想外面那些非常小的蠕蟲和蒼蠅。
而T. magnifica攜帶有大量的DNA。如果你計算它的生命密碼或基因組中的所有 "字母"，或鹼基，大約有1200萬。但是在每個細胞中，可能有50萬個基因組的副本。
"These bacteria are about 5,000 times larger than most bacteria. And to put things into perspective, it is the equivalent for us humans to encounter another human who would be as tall as Mount Everest," said Jean-Marie Volland from the Joint Genome Institute at the Lawrence Berkeley National Laboratory, in the US.
Centimetre-long T. magnifica is not the largest single-celled organism on Earth. That's probably a type of aquatic alga called Caulerpa taxifolia which is 10 times longer still. But the bacterium is definitely impressive when you consider there are many, much more complex life forms on Earth that require some sort of magnification to be observed. Think of those really teeny worms and flies out there.
T. magnifica was first identified back in 2009 in Guadeloupe, in the Lesser Antilles. But it was initially put to one side. Only recently have Dr Volland and colleagues got around to studying it in detail.
It's a significant revelation because until now, the packing of DNA inside a membrane-bound compartment was considered the preserve of so-called eukaryotic cells, which are the building blocks of higher organisms such as humans, other animals and plants.
And T. magnifica carries a lot of DNA. If you count all the "letters", or bases, in its life code, or genome, there are some 12 million. But in each cell, there may be half a million copies of the genome.
"If you now take the genome size of 12 million bases, multiply that by the number of genome copies - so, half a million - you end up with approximately 6,000 giga, or billion, bases, of DNA. For comparison, a diploid human genome is approximately six giga bases in size. So this means that our Thiomargarita stores several orders of magnitude more DNA in itself as compared to a human cell," explained Dr Tanja Woyke, also from Lawrence Berkeley.
In all that DNA, there are clues to the drivers of the organism's great size, she added. Some genes associated with elongation seem to be duplicated and some genes ordinarily involved in division appear to be missing.
T. magnifica is a chemosynthetic bacterium. It makes the sugars it needs to fuel itself by oxidising the sulphur compounds produced by the rotting organic matter in the sediments of the mangrove swamp. All it needs is something solid to hang on to.
"They just need some hard substrate to be in contact with the sulphides and in contact with the seawater to get oxygen and CO2. The highest concentration of Thiomargarita I found was on a plastic bag - unfortunately."