Wee Knight Science: Bioremediation by bacterial badasses part 2: How do bacteria digest toxic waste?

If you haven't checked out part 1, you should! Unless you know how heavy metals are poisonous, then you're already caught up.

Ok, so stuff like radioactive waste and oil are bad for the environment. Thus, it might be a good idea to clean that stuff up if it gets where it's not supposed to be. Unfortunately, you can't just mop it up with a paper towel like that time you spilled wine all over your grandmother's new carpet (you drunkard, you). There are some very smart people trying to design materials that can act like paper towels and sop up bad stuff, and I'll include some links at the end if you want to read more about that business. However, I promised you bacteria, and bacteria you shall have! Let me introduce you to my friend Geobacter. You can call him Geo.

Don't mind me. I'm just chillin', saving the environment and stuff.

Geo is kind of an oddball. Like many bacteria (and higher organisms such as ourselves), Geo likes to eat sugars and/or small, sugar-like molecules (e.g., acetate, malate), because sugar is delicious.

Take a break if you need to and go find some candy.

But, Geo also eats metal and petroleum, because he doesn't care about your rules.

Imagine a bacterium sitting in that swing seat, if you would.

You see, most (possibly all) organisms make high-energy molecules using what is called an electron transport chain. We can think of it this way: in general, organisms receive energy (eat) from a lot of different sources. That is apparent just by looking around us. Humans eat pretty much anything that stands still long enough; chickens, broccoli, termites (check this out!) Dogs are so anti-picky, they eat their own puke--among other things...

But wouldn't it be kind of a pain if we had to build cars that ran on gasoline, natural gas, electricity, hydrogen, solar power, wind power, etc.? That would be pretty silly, so most cars are powered by just gasoline.

Cells are the same as cars. A lot of proteins--our handy-dandy molecular machines--are powered by ATP (adenosine triphosphate).

You have about 250 grams of me right now. Picture--Ben Mills

Alright, back to the electron transport chain (ETC). The basic idea isn't really intuitive to me, even though I've worked in biological sciences for several years now, so I'm going to do my best to break it down into something simple but still fairly accurate.

ATP is a way for you to store energy. Returning to the car analogy, you probably fill up your tank when it starts getting low, but most of the time you don't use all that gas at once. You drive to work, you go to the grocery store, you visit your friend's house a few minutes away. And you can do this because gasoline is a source of energy that can be stored. Sunlight is a form of energy, too, but if you don't have a solar panel to soak it up and put it inside a battery, you can't use the sunlight later. So, ATP is one of the reasons why you don't need to constantly eat to power your body.

The way the ETC works is kind of like this: you have a vehicle that you want to drive down a hill at midnight. The vehicle can only run when the sun is shining on it. So, you drive the vehicle to the top of the hill during the day, then later that night you can just give it a little nudge and it will roll down the hill. ETC is how your cells get the vehicle up the hill.

That's great, but what does this have to do with our old friend Geo? Geo has the neat ability to use nasty stuff like oil and uranium as steps in the ETC. It can bounce electrons through them to other molecules to make ATP.

Why can't we do that? We just don't have the machinery! Like I said earlier, proteins do everything for us. We don't have the same proteins that Geo uses to eat up toxic waste.

Geo has already been useful in cleaning up the streets, and a lot of people are trying to figure out how he does his job and maybe how to help him do it better, like a bunch of Commissioner Gordons rooting for Batman.

I am the night!

Some people are even thinking about using him to make batteries! But let me not leave you thinking that Geo is the only quicker-picker-upper out there. He has friends like Pseudomonas putida and Deinococcus radiodurans. I've heard they like to have parties and talk about all the seagulls they've saved.