Toxic-Waste Consuming Bacteria

cswiii writes "CNN has this article about scientists who have created bacteria that consume toxic wastes, such as radioactive materials, breaking them down into less harmful compounds. " Similar work has been done before with genetically engineering trees. I believe that bactera that eats oil has been actually used in oil spills before.

Comments

Finally a topic in my specialty

[Jon_S]

That this bacterium can withstand such high levels of radiation is truly unique. However, not much else about it is. Bacteria are routinely used in site cleanups. The most common use of bacteria is the degradation of organic compounds, primarily hydrocarbons. In this case, the hydrocarbons are aerobically transformed to carbon dioxide and water. Other compounds are also biodegradable to more or less extents. Chlorinated compounds are difficult (primarily due to the steric hindrance caused by the large chlroine atoms), but are subject mainly to anaerobic degradation through reductive dechlorination, or cometabolic degradation.

Now what this article is discussing is a bacterium that transforms mercury. There is also a lot of literature about "metals biodegradation", but of course, metals are elements, and can not be destroyed. What happens in "metals biodegradation" is that the metals are transformed into different oxidation states that are less toxic or harmful. For example, hexavalent chromium is significantly more toxic than the trivalent form.

In the case of mercury, the main concern is methylated mercury versus elemental or ionic mercury. Methylmercury is the most toxic form since it can bioaccumulate (essentially acting like an organic due to its methyl groups) and thus more easily get taken up ny living organisms (nothing is toxic to you unless you get it in your body by ingestion, inhalation, or through dermal absorption. This excludes radiation, of course). So I am guessing that this bacterium somehow demethylates methylated mercury. It probably produces elemental mercury (i.e. liquid mercury) which is less likely to be ingested, or else some sort of mercurous or mercuric salt that is insoluble (mercuric phosphate, maybe?) and not likely to be remetabolized into the methyl form.

Not radioactive compounds, but toxic heavy metals

[Signail11]

The genetically altered bacteria Deinococcus radiodurans does not consume radioactive compounds as the summary suggests. As physics assures us, it is [almost] impossible to alter the half-life of a radioactive compound or transmutate elements without massive equipment. OTOH, what these bacteria do is that they have been genetically customized to transform highly reactive heavy metal compounds into more tame and benign materials. The "radiodurans" part of the name refers to the fact that the bacteria can withstand "1.5 million rads of gamma radiation, or about 3,000 times the lethal dose for humans." Pretty amazing stuff.