baudrunner's space: Bacteria can make us better

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Tuesday, January 22, 2008

Bacteria can make us better

Much of the gold in Australia lies in quartz veins where it exists as sub microscopic particles too tiny for even high powered electron microscopes to resolve. But the soils above the quartz contain grains and nuggets of gold. Dr Frank Reith from the Cooperative Research Centres (CRC) for Landscape Environments and Mineral Exploration has confirmed that the bacteria Ralstonia metallidurans plays an important role in separating the gold particles from the microbial ecosystem and that this action removes an important toxin out of the environment so that other bacteria can thrive.

The microbe Bacillus pasteurii has been shown to alter the chemistry of soil grains in wet soil to form calcium carbonate, which is an ingredient in cement. Studies on this particular species of bacteria were done because it was already known for making water in soils more alkaline. Earthquakes are known to liquefy already stressed solid rock under buildings and this bug shows promise in stiffening the loose fill or liquefied rock under structures by binding the gaps between sand grains with calcium carbonate crystals, effectively locking them together. The goal is ultimately to harness the quadrillion or so microbes that exist in every cubic metre of soil to serve the construction industry, according to engineering professor Carlos Santamarina of the Georgia Institute of Technology in Atlanta, who also works on bio-alteration of soils.

One of the biggest polluters of soil and ultimately groundwater are chlorinated solvents, which have been universally used since the 1940's as industrial degreasing agents. They seep out of leaky rusted out storage barrels buried in industrial waste sites. There are well over 150,000 contaminated sites in North America. Researchers at the NRC Biotechnology Research Institute (NRC-BRI) have developed a catalyzed bioremediation technique utilizing both aerobic and anaerobic bacteria working together synergistically to stimulate the bacteria to convert the dangerous toxins into CO2 and water with harmless chloride salts as a byproduct. Catalysis is provided through the electrolysis of water which feeds the bacteria oxygen and hydrogen thus speeding up the process. The NRC team have built a portable unit for on-site treatment of contaminated sites by biostimulation.

Researchers at University of Arizona and at Queens University in Belfast have discovered that microbes that self-fluoresce under laser illumination may have potential for acting as junctions in biophotonic transistors. The microbe Pseudomonas syzgii was originally the object of a search for the means to destroy it. The bug invades semiconductor materials through the manufacturing process through ultrapure water and all attempts to remove it failed. It protects itself by chewing away a little of the semiconductor material and wrapping itself up in it, actually creating a new transistor in the process because electrons can flow across the surface. The bacteria provides a variable negative charge to amplify or attenuate electron flow depending on the amount of fluorescence it produces when it is exposed to light. Ongoing research will involve the Institute for Lasers, Photonics and Biophotonics.

Recent research into the use of bacteria as vectors for the delivery of "smart nanoparticles" into diseased cells shows great promise. Successful experiments were carried out on human cancer cells, including intestinal, oral, liver, ovarian and breast cancer cells. The nanoparticles are the carriers of the therapies intended for delivery into the cell and once inside they release their cargo in a precisely timed manner. Using this method, a single bacteria can carry hundreds of different nanoparticles, compared to other research using viral and bacterial vectors which could only deliver one copy of the gene cargo to each bacterium or virus particle.

Membrane microbial fuel cells using Geobacter microbes obtain their electrons from organic waste. NASA is funding a research team led by Dr. Bruce Rittmann, a professor at Northwestern University, to investigate the possibility of using these bacteria to recycle human waste into water and electricity on long term missions such as the manned mission to Mars. As part of their digestive process, geobactor microbes pull electrons from waste material. It might be possible to deliver the electrons directly to a fuel cell electrode. Current transfer rates are too slow to be practical since only a very small part of the microbe touches the electrode but the microbial fuel cell is still in the early stages of development. Eventually the problems will be overcome.

The bacteria S. marcescens will some day become the workhorse for precise drug delivery inside the liquid environments of the human body, such as the urinary tract, eyeball cavity, ear and cerebrospinal fluid. These are the same kind of bacteria that cause the pink stains on shower curtains. They propel themselves using their corkscrew like tails, called flagella. Research at Carnegie Mellon University in Pennsylvania is unlike other experiments which harness the motion of a bacteria's flagella in that the entire microorganism is used so they can be more easily integrated with other microscopic components without requiring purification or reconstitution, as do detached bacterial components. Metin Sitti and Bahareh Behkam are using chemicals to selectively turn the motion of the microbes on or off. Copper sulphate is added to the glucose water solution wherein they have suspended a chain of polystyrene beads to which the microbes cling. This stops the forward motion of the glucose feeding bacteria. Another chemical called ethylenediaminetetraacetic acid (EDTA), which traps the copper ions, is added to the solution to restart the motion. Perhaps they have finally found the means to rid the retinas of those annoying protein particles that intrude on my vision.

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