MadSci Network: Microbiology

Re: How do oil-eating bacteria work?

Date: Mon May 10 11:42:43 1999
Posted By: Andrew D. Brabban, Faculty, Biology, The Evergreen State College
Area of science: Microbiology
ID: 926226583.Mi

To begin with lets break this down into its constituents, oil and 
microorganisms. Oil is an energy source to us humans but we do not view it 
as a food. What is a food ?. Well we consider food things like sugars etc. 
but the difference between these compounds and crude oil is basically non-
existent, they both are energy and carbon rich. Just because we can not use 
crude oil (remember we can use other oils such as olive oil as energy 
sources) we dismiss it as not a food. So what is crude oil ? Well itís a 
very complicated mix of a wide variety of carbon compounds from cyclic and 
polycyclic hydrocarbons (benzene, napthalenes etc.) to straight chained 
aliphatic compounds such as heptane and octane. To us its toxic, to a number 
of microorganisms its just like candy. So how can microorganisms use it and 
we can't? Well it all breaks down to diversity, evolution and biochemistry. 
Microorganisms are a very diverse group. Animals and plants are nearly 
identical to one another when you compare how different microorganisms are. 
They have been on this planet for over 3 billions years, we as humans only 1 
million. They have adapted (evolved) to use all the available nutrients they 
can and some individual species (Pseudomonas) can use up to 1000 different 
carbon compounds. What do they do with the oil ? Well basically they eat it 
just like you eat cereal. They use enzymes to break it up (metabolize it) 
using O2 turning it into CO2 and more microorganisms. Itís the initial 
enzymes that are special. They break down the petroleum substituents into 
smaller molecules that can enter central metabolism. Central metabolism then 
routes these chemicals to make energy, and materials for new cells (this is 
just the same as you). Three years ago I was lucky to meet one of the people 
who used microorganisms to clean up the Exxon Valdez spill. The beaches 
treated with microorganisms were cleaned much more effectively and faster 
than the ones they used detergents etc on. What they were actually doing was 
merely enhancing the natural process. Ever think where that oil goes over 
the years. Well the microorganisms eat it. Try it some time. Take some old 
oil (0.1 ml) and add 100ml of tap water to it. Leave it open to the air and 
watch what happens, shake it about once or twice a week. Give it a few 
weeks, microorganisms will grow probably pseudomonas and fungi. So to 
conclude they metabolize oil just like a food to carbon dioxide and new cell 
material (more microorganisms), they are naturally present everywhere but 
some have been genetically modified by industry to be better at doing it, 
and they can do this because of the enzymes they produce.

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