Epulopiscium fischelsoni - Behemoth Bacteria
Candice Luehrs
What do Dinosaurs and Epulopiscium fischelsoni have in common?
     They are billions of years old?  Nope, try again....
     They are both extinct?  Wrong again, One more try...
     You can find information on both of them on the Internet?  And the Survey says....XXX.

Dinosaurs and Epulopiscium fischelsoni are the largest of their types to ever exist on earth.  E. fischelsoni is the largest bacterium known to man (about the size of a printed hyphen (-)).  In fact, when it was first discovered by Linn Montgomery at Northern Arizona University in Flagstaff and examined by Norman Pace at Indiana University in Bloomington in 1993, it was believed to be a protist due to its size.  The organism was found in the guts of several kinds of surgeonfish which live in and around coral reefs in Australia, Hawaii and other island environments.  The organism could not be grown in lab which slowed the research process.  Pace used a DNA analysis technique to determine the nature of the organism.  Once it was determined that E. fischelsoni was indeed a prokaryote it raised new questions: What does it eat? What is it related to?  Why in the belly of fish? How does it reproduce? What are its main functions? How is it able to survive with its large size?

The researchers are still unsure of the purpose they serve or what they feed on but they were able to answer a few of the other questions.  First, the organism has been found to be part of the Clostridium group of anaerobes and is rod shaped.  It can grow up to 600 micrometers long by 80 micrometers wide.  They are able to survive because they can maintain a surface area to volume ratio that allows them to efficiently transport goods throughout themselves.  They are able to do so because their outer membrane is not tightly stretched around the cell but has many folds, like the intestines of humans, which allow for more surface area.  To illustrate this, imagine a paper bag.  Opened up it has a volume which allows a lot of "stuff" to be held inside of it and a set amount of paper to form the surface area.  When the bag is crumpled up the surface area is still the same but the volume is significantly decreased.

E. fischelsoni also has a reproduction system unique among bacteria.  They have viviparous offspring which means production of live young from within an organism, as opposed to eggs.  It can generate living cells inside of itself, therefore producing like a mammal.  Two "baby" bacteria are formed at one end of the mother cell and after the cell wall synthesis is complete for each cell the "babies" are released through a slit that opens at the end of the mother cell.  This process is slightly different from sporulation in that it is the main form of reproduction whereas sporulation is a process that is carried out to protect the species when an organism senses danger in its environment.

As far as what it is doing in the intestines of surgeonfish, Montgomery thinks the bacteria "may enhance lipolytic activity in the main intestine." and researchers know that it greatly suppresses pH locally in the mid-intestines.

Researchers believe that this bacterium can be used to directly study bacterial physiology due to its large size, since it allows for the insertion of probes which can't be carried out in most bacterial species.

Pace believes that the attention that the E. fischelsoni has drawn due to its size is more valuable not in the fact that this huge organism was discovered but the techniques used and their usefulness in examining undiscovered microbes.  His technique focuses primarily on organisms that as of yet have not been amenable to enrichment culturing.  Basically he amplifies the DNA from the bacterial cell and compares it with known sequences of rRNA to determine the phylotype amongst known organisms.

So basically, that is all there is to say about what there is not much to say about Epulopiscium fischelsoni.



*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.


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