Cornell researchers study bacterium big enough to see
This giant among bacteria, Epulopiscium sp., lives in a symbiotic relationship in the gut of surgeonfish around Australia's Great Barrier Reef. The research shows how a simple modification in the basic design of bacterial cells allows Epulopiscium sp. to grow so large.
"Other bacteria have multiple copies of their genome, but prior to this, I think the highest numbers known have been a hundred or a few hundred copies," said Esther Angert, a Cornell associate professor of microbiology and the paper's senior author. "The big discovery is seeing this bacterium with tens of thousands of copies of its genome."
Most bacteria are small and appear to be structurally simple. They lack the specialized organelles that allow eukaryotic cells (cells in which DNA is contained within a nucleus) to take in nutrients, organize cellular functions and maintain larger sizes. Bacteria instead rely on diffusion through their cell membranes to obtain nutrients and other important chemicals. Since bacteria cannot move nutrients within the cell body, they need to stay small for diffusion to work well.
But, by copying its genome thousands of times and arraying it in a kind of fabric just under the cell membrane, Epulopiscium sp. may maintain its large size by keeping its DNA close to the outer surface, Angert said. That way, the DNA may respond quickly and locally to stimuli by producing RNA and proteins where they are needed.
"Having copies of its genome arrayed around the periphery keeps the DNA close to the outer environment," said Angert. "The bacterium can immediately react as something comes in contact with the cell."
The bacterium's large size offers advantages: It is highly mobile and too big to eat for most protozoan predators that also live in the surgeonfish's gut.
Also, while most bacteria reproduce by dividing into two equal-sized offspring, Epulopiscium sp. produces offspring internally, usually two, one at each pole of the cigar-shaped cell. These polar cells grow within the mother cell's cytoplasm, until the mother cell eventually bursts open and dies.
"We're interested in how that process arose and how that may affect the biology of the organism," said Angert.
Most read news
Other news from the department science
These products might interest you
Hydrosart® Ultrafilter by Sartorius
Efficient ultrafiltration for biotech and pharma
Maximum flow rates and minimum protein loss with Hydrosart® membranes
Hydrosart® Microfilter by Sartorius
Hydrophilic microfilters for bioprocesses
Minimal protein adsorption and high flow rates
Polyethersulfone Microfilter by Sartorius
Biotechnological filtration made easy
Highly stable 0.1 µm PESU membranes for maximum efficiency
Sartobind® Rapid A by Sartorius
Efficient chromatography with disposable membranes
Increase productivity and reduce costs with fast cycle times
Sartopore® Platinum by Sartorius
Efficient filtration with minimal protein adsorption
Reduces rinsing volume by 95 % and offers 1 m² filtration area per 10"
Polyethersulfone Ultrafilter by Sartorius
Reliable filtration with PESU membranes
Perfect for biotechnology and pharmaceuticals, withstands sterilisation and high temperatures
Get the life science industry in your inbox
From now on, don't miss a thing: Our newsletter for biotechnology, pharma and life sciences brings you up to date every Tuesday and Thursday. The latest industry news, product highlights and innovations - compact and easy to understand in your inbox. Researched by us so you don't have to.