In our first lecture, we were introduced, once again to cells. To be honest, it was a lot like revision for me since I’ve been doing this for what seems like forever. But there is one thing that really got me thinking. Is the dialister pneumosintes bacteria REALLY the smallest free living cell? After I went on to do my own investigation, I found that this really was the case BUT, doesn’t that make you wonder what the largest bacteria ever discovered is? Well, allow me to enlighten you.
The colossus among bacteria is a single-celled giant that lives in the ocean and is named Thiomargarita namibiensis <thigh-oh-mar-ger-ee-tuh nah-mih-bee-en-sis>, which means “sulfur pearl of Namibia.” It was found in the ocean floor off the coast of Namibia in Africa. T. namibiensis’s ball-shaped cells can grow to almost 1 millimeter or 1/25th of an inch in diameter. That’s about as big as the period at the end of this sentence. Size-wise, the largest T. namibiensis cell is to an ordinary bacterium what a 75-foot (23-meter) blue whale is to a newborn mouse. Wow! Cells of Thiomargarita namibiensis are large enough to be visible to the naked eye. Although the species holds the record for the most massive bacterium, Epulopiscium fishelsoni, previously discovered in the gut of surgeonfish, grows slightly longer, but narrower.
You may be wondering what it looks like. Take a look!
Weird looking isn’t it?
Now, I remember a point from my lecture that stated that a bacterium of large size would imply a lower ratio of cell membrane surface area to cell volume. This would limit the rate of uptake of nutrients to threshold levels and removal of waste from the cell. Large bacteria might starve easily unless they have a different backup mechanism. So…how does the T. namibiensis survive? It overcomes this problem by harboring large vacuoles that can be filled up with life-supporting nitrates to sustain its life. T. namibiensis “eats” sulfur and “breathes” nitrate. It stores these molecules in bubble-like compartments in its cell called vacuoles. These vacuoles take up 97 percent of the space inside the cell and give the bacterium a pearly, blue-green color. Basically, these vacuoles act like food storage and scuba gear, enabling the bacterium to survive long periods when sulfur and nitrate are scarce without “starving” or “suffocating.” Pretty cool I think 🙂
Photo Credit: [http://summerhillbiology10.blogspot.com/2012/04/la-bacteria-mas-grande.html]
Photo Credit: [http://davesgarden.com/guides/articles/view/1641/#b]