MRS: wrapping up bugs to clean up water
I just saw a really neat presentation, by Ying Li, from Stony Brook University. She is working on ways to clean up water contaminated with radioactive waste. It turns out that a certain type of microbe, Pseudomonas Fluorescens, can gobble up 98% of radionuclide contaminants.
Li has taken this and applied it to a flitration system. She has managed to trap the bugs in a polymer, which can then form part of a membrane filter. The reason this is hard is that microbes usually live in watery places, whereas most polymers are soluble in organic solvents only.
But some water soluble polymers do exist - which means microbe trapping can be done. The problem then is making the polymer insoluble in water again so that it doesn't get washed away when acting as a filter.
Li managed to trap the bugs in a polymer called F-127 DMA, a fibrous polymer. She showed nice electron micrographs of the fibres bulging, like a pea pod, where the microbes were encased. Amazingly the microbes can survive, dormant, in these dry, sometimes hot, nutrient-sparce environments only to spring back to life when placed back in a watery, foody place.
The next step was to make the polymer insoluble again, and Li did this by cross-linking the fibres - making a big messy ball that is hard to dissolve. Again, 40% of the microbes survived this process.
Because the polymer is based on a hydrogel, and is porous, this means that water can penetrate it. Which in turn means that dirty water can get into the fibres with their trapped microbes, and hey-presto! clean water.
