Bacteria As Fuel Cells? 122
KantIsDead writes "MIT's Tech Review is running an interview with Boston University Bioengineer Tim Gardner about the possibility of using bacteria to produce electricity. If fuel cells running off sugar are nearly here, alcohol-powered robots cannot be far." From the article: "While typical fuel cells use hydrogen as fuel, separating out electrons to create electricity, bacteria can use a wide variety of nutrients as fuel. Some species, such as Shewanella oneidensis and Rhodoferax ferrireducens, turn these nutrients directly into electrons. Indeed, scientists have already created experimental microbial fuel cells that can run off glucose and sewage. Although these microscopic organisms are remarkably efficient at producing energy, they don't make enough of it for practical applications."
Re:Bacteria As Fuel Cells? (Score:3, Insightful)
Considering bacteria belong to the kingdom Monera and not Animalia, I doubt that.
Re:Mutations (Score:3, Insightful)
Or just use a fresh starter of bacteria for each batch. That's basically what bakers do today with yeasts: in the past, a good bakery would have had a 'starter' filled with yeast, which they'd put a small piece of into each batch of dough. Over time, particular bakeries ended up having particular strains of yeast, which makes for interesting flavors of bread but probably isn't a great idea if you're making industrial products. So instead you do what most bakeries do now: just treat the yeast as consumable, and add some fresh stuff to each new batch, ensuring that it doesn't make it into subsequent batches. That improves quality control, and doesn't give the yeast an opportunity to mutate very much.
All of this of course is dependent on the ability to preserve the bacteria while they're not actively reproducing. This is fairly trivial with yeasts (those little packets have a shelf life of a few years!), but might not be with the bacteria in question.
Not sure about that. (Score:3, Insightful)
I'm not sure this is a good assumption. If the bacteria were a product of genetic engineering and not selective breeding in that environment, they might be easily overwhelmed by a mutant strain that was more suited to the environment, but less useful to us. For example, we might engineer bacteria that produce electricity, but do it at the expense of reproduction rate. If a mutant strain appeared that didn't have that characteristic (i.e. if it didn't produce as much electricity but reproduced faster) then it would probably overtake the preferred/engineered strain.
Make bacteria dependent i.e lac operon, etc (Score:4, Insightful)
It would be unlikely for the bacteria to spontaneously mutate out 2 genes at once, thereby subverting our design. Obviously bacteria, number in the billions, so it will be necessary to restock our fuel cell occasionally. Of course you could be clever and tie in a third gene that gives immunity to a toxic substance, so that non-desired mutated bacteria are killed off automatically.
Bacteria Can't Scale? (Score:4, Insightful)
There's something wrong with this sentence. It sounds like they're saying that the bacteria perform an efficient conversion of the sugar energy into electrical energy, but that the problem is that bacteria can't be scaled effectively to produce significant amounts of power.
There's a problem with the idea that bacteria don't scale. Bacteria are well known for their exponential growth curves. Give me a sufficently large petri dish with medium and a starter batch of bacteria, and I'll solve your scaling dilemma.
If they are truly efficient, then there's no problem with bacteria not making enough power, as making more bacteria is trivial. However, I don't think it's likely they really are efficient. It seems highly unlikely bacteria would waste much energy on producing unused electricity, one might expect them, like most living things, to use most of their available energy growing, respirating, reproducing, and anything else that generally falls under the category of "surviving." Sure enough, later in the article comes:
Gardner's team aims to harness the genetic control system to engineer bacteria that can produce energy more efficiently.
Which makes me think that the problem with the current bacteria is efficiency, not scalability, as the first sentence implies. Perhaps by "efficient" he means that they don't produce a lot of waste heat or something, but for generating electricity, the definition of efficiency should be what percent of the energy they take in they put back out as electricity.
Re:Medical implants (Score:3, Insightful)
Your immune system deals with them. If they're not optimized to reproduce in that environment, there wouldn't even be much risk of "spread". Not all bacterias thrive in the human body, after all.
2) Could an antibiotic cure for an unrelated infection kill my artificial heart?
Presumably your artificial heart's bacterial power source would not be exposed to your body, any more than today's artifical hearts press their battery leads right up against exposed tissue.
Re:Mutations (Score:3, Insightful)
When (not if) it happens, we kill the results and don't let them breed.
Why do you think it'll be any different with the bacteria? It's not as if all the bacteria in the world will be in one tank in one gigantic, completely inseperable pile.
Re:Not sure about that. (Score:2, Insightful)
Best solution I could think off would be to divide the surface that the bacteria grow on into discrete areas maybe 1cm squared and monitor the current received from each square.
Once a day, kill off everything on the area which produced the smallest current, maybe by heating the surface somehow.
you would probably end up using more energy destorying bad areas than you would gain but it might extend the useful strains working life - if you are lucky, you might even end up with a more productive strain without any genetic engineering needed.