Making acetic acid via photosynthesis isn’t really terribly newsworthy but they could do it really efficiently. How efficiently? Like 80 percent. How on earth did they get that efficient? Well, the surfaces of the bacteria were covered with tiny semiconductor crystals and the best part the bacteria made those semiconductor crystals themselves.
So Why Is That Good?
Well, it’s good if we can get bacteria to produce acetic acid because that useful for all kinds of things like making some kinds of plastics perfumes or dyes or inks but bacterial production of chemicals can be hampered by their relative inefficiency so researchers have been thinking how can we make it more efficient. Wait a minute! Some bacteria have developed resistance to heavy metals by turning them into sulfides normally bacteria exposed to cadmium or mercury or lead would be in very bad shape, to put it mildly but these bacteria convert them to tiny sulfide crystals which then sit on the bacterial surface which as it turns out is kind of like having your own solar panel.
The bacteria can then photosynthesize at an efficiency rate of 80 percent taking in light and water and carbon dioxide and giving out acetic acid 80 percent efficiency is incredible. It’s about four times higher than commercial solar panels and six times higher than plant photosynthesis. So you take your liquid broth in which you have your bacteria. You add some cadmium you come back later and the bacteria are now coated in cadmium sulfide, you put it in sunlight.
Now they can photosynthesize really well and then the researchers take that acetic acid and give it to their collaborators who have modified some e coli strains to use acetic acid as their food source these e coli strains can then produce butanol and polyhydroxybutyrate which you might have guessed from the name is a polymer. Now the researchers have said that it would be good to find substance less dangerous to work with than cadmium but this is super cool you just need a big vat of liquid which you keep in the sunlight you add the cadmium boom! You’ve got acetic acid from which you can make all kinds of useful things! Chemistry meets biology and it’s kind of beautiful.