Scientists discover gas guzzling bacteria
Sea-bed dwelling bacteria which live off a diet of gas have been discovered by a team of German and American scientists. The depths of the sea floor are not an easy place to live; even just a few millimetres below the surface, there is often no oxygen. Food is also in short supply, as the nutritious proteins and carbohydrates found in fresh plankton are consumed higher up the water column. The remains that reach the sea floor are the parts that are hard to digest. Nevertheless, the sediments of the seafloor do harbour life, in the form of micro-organisms such as bacteria. Now scientists have discovered a group of bacteria whose diet consists of the short chain hydrocarbons ethane, propane and butane. Although aerobic (oxygen-breathing) bacteria with a similar diet have been found before, this is the first time that anaerobic, gas-feeding bacteria have been found. They isolated the bacteria from oxygen-free mud taken from gas seeps in the Gulf of Mexico. They then shut them in bottles together with the hydrocarbon gases under study, but without oxygen. They found that the bacteria use sulphate from the sea water to convert ethane, propane or butane into carbon dioxide; during this process the sulphate is itself converted into hydrogen sulphide. The newly discovered organisms are extremely slow in growing, taking three days to divide (compared to the 30 minutes for the bacteria used to produce yoghurt). The findings solve a number of mysteries, such as the disappearance of ethane, propane and butane, as well as methane, from mud volcanoes. The bacteria could also be useful in industrial biochemistry; they must have a special digestive enzyme to be able to break down chemically stable substances such as ethane without the help of heat or chemicals like oxygen. If a similar enzyme could be produced artificially, it would surely be interesting for chemical synthetic processes, the authors speculate. The study is published online by the journal Nature.
Countries
Germany, United States