Old McDonald had a Colony of Bacteria

..Or is it a swarm of bacteria? A school? Pack?! Herd!?!

Whatever the group designation may be, the majority of bacteria used in research nowadays have been domesticated much like dogs were domesticated from wolves. In fact, bacteria may just hold the world record for “Most Recently Domesticated Living Organism”. Unlike their wild type brethren, laboratory strains of bacteria have lost their wild features that allow them to thrive in their normal habitats. Let us focus specifically on E. coli for the sake of simplicity.

You may have heard of E. coli from its association with food borne illnesses caused by eating tainted meat and produce. However, what you may not realize is that not all E. coli are bad. Surprisingly, E. coli are important players in the production of proteins such as enzymes in your laundry detergent. Thought your whites came out whiter because of that new washing machine? Think again! But how did E.coli  go from giving us diarrhea to cleaning our diarrhea-stained clothing? The answer is through domestication!

Domestication of bacteria: Parental bacteria found in the intestines. Subsequent passages grown on Petri plates.

E. coli was originally isolated from the jungles of the human intestine in 1885 by Theodor Escherich. Few studies were carried out on this bacteria until 1922 when wild type E. coli’s domesticated counterpart, E. coli strain K-12, was found in the stool sample of a diphtheria patient. A pure culture of this strain was maintained in the cushy labs of the prestigious Stanford University (Bachmann, 1972). Due to its comfortable living situation, E. coli K-12 soon lost many of the traits that enabled its wild counterparts to survive in the gut. Even pathogenic E. coli today, such as the notorious E. coli O157:H7, have the potential to become as harmless as the K-12 strain. With enough generations grown in a nurturing environment, harmful bacteria can afford to discard their defenses and are no longer a threat to humans. 

Multiple transactions later...
E. coli’s loss of disease causing potential became an opportunity for scientists to continue their research on this organism without much risk of exposure to an opportunistic pathogen. From this K-12 strain arose a multitude of E. coli strains, such as strain AG1 and strain MG1655, each one possessing a slightly different genetic profile. To date, a large number of lab strains of E. coli exist; each developed for a different research purpose and each one missing a combination of genes—termed knockouts—for the study of different metabolic pathways and/or reactions to various external stimuli.

Effects of external stimuli

Study of metabolic pathways

As scientific techniques became more advanced, researchers began to take advantage of the rapid replication times of E. coli and its genetic manipulability to synthesize proteins in a fast and cost effective way. Much like how dairy cows are bred to overproduce milk, strains of bacteria in biotechnology companies are genetically manipulated to churn out protein products such as insulin and enzymes to be added to laundry detergent, just to name a few.

Genetic manipulation of E. coli. P = Protein Product

So the next time you do a load of laundry, take a moment to thank the lowly E. coli, an often misunderstood bacterium that was plucked from the obscurity of the intestinal tract, domesticated on a Petri plate and turned into miniscule protein farms.

E-I, E-I, O.   


*Pictures are not drawn to scale; E. coli are not known to have faces 

The Ooky, Spooky, World of Microbes

     One doesn't need to look to fiction to conjure up images of predatory beings that prey on the lives of others.  The natural world, in this case, the microbial world, provides such predatory examples.  For instance, Dracula can't hold a dungeon torch to terrifying microbes like Vampirococcus, who "suck" the life out of unsuspecting bacteria.  Likewise, the brain-dead zombies of The Night of the Living Dead don't compare in mindless self-destruction to ants infected with the zombie-inducing fungus Ophiocardyceps unilateralis.  These are just two of many parasitic microbes that make a living.....off the lives of others.....

     Let's begin with the Vampire of the Microbe World, a cell sucker from the informally named genus Vampirococcus.  The name originates from the root words "vampire", which is Serbian for vampir or bloodsucker, and "coccus" which is Greek for a grain or berry. But don't be fooled, this ain't no bloodsucking berry, it's a microorganism, more specifically a bacteria!  That's right, these guys are so small that you can't see them without the help of a microscope!  These tiny terrors lurk in the murk of freshwater lakes.  Don't worry though, these beasties aren't interested in humans, instead they prey on purple phototrophic (meaning using light as an energy source similar to plants) bacteria of the genus Chromatium.  In true vampiric form, Vampirococcus attaches to the surface of the Chromatium cell wall and "sucks" out the nutritious innards.  Why?  Well, just like vampires need to drink blood to survive, Vampirococcus needs to drink the insides of the Chromatium to survive.  Unlike vampires though, Vampirococcus doesn't transform Chromatium into one of them, instead, they tend to "suck" Chromatium dry and use the nutrients and energy they get from "feeding" on Chromatium to divide and make more of themselves.  I know, it is a cruel world out there, no matter what size you are.
    
     If that wasn't terrifying enough to make you run for the nearest bottle of antimicrobial soap, imagine that you’re walking down the street, minding your own business, and all of a sudden you start to lose control of your body and can’t seem to move it the way you want it to. Something has possessed you and like a zombie, you have lost all control.  You're nothing but a shell of your former self, being forced to do the bidding of whatever has just hijacked your mind and body.  This sounds like something taken out of a zombie horror movie right? Wrong! This scary scenario can happen in real-life, but fortunately for us, the unsuspecting victims to this real-life horror story are a few selected species of ants from the tribe Camponotus and the mind-controllers are the fungal pathogen Ophiocardyceps unilateralis.

This fungus thrives in conditions where the temperature is 20-30 degree Celsius with humidity of 94-95%, and is a certain distance above ground. This is often the underside of a leaf that is 25 centimeters above ground. To get to this perfect spot, Ophiocardyceps unilateralis infects these ants, leads them away from their home, and forces it to travel to this ideal location. Once these zombie ants are anchored at their target site, spores from the fungus explode out of the ant’s head, effectively killing the ant. The fungus selfishly continues to grow and the spores released are now out to infect other poor unsuspecting ants, continuing this nasty cycle.

Now, it needs to be mentioned that not all microbes (in fact the majority of microbes) are predatory like these two fiends but were highlighted here in the spirit of the holiday.  HAPPY HALLOWEEN!