Oil-Eating Bugs

Petroleum is a mixture of hundreds of hydrocarbons--chemicals containing the elements carbon and hydrogen. These range from propane (heating gas) through gasoline and lube oil to naphthalene (moth balls) and asphaltenes (highway blacktop). As a result of petroleum transportation and natural processes (green plants make hydrocarbons), millions of tons of these compounds enter the oceans every year. About 6 million (0.3%) of the 2 billion tons of petroleum produced each year are spilled into the oceans.

Particularly in coastal areas this oil would persist were it not for the bacteria that eat it. Other microorganisms metabolize oil too, as do higher organisms. Whereas humans do not gain energy from ingested hydrocarbons, many species of microorganisms--bacteria, yeasts and fungi--obtain both energy and tissue-building material from petroleum. These microorganisms require both the existence of oxygen and certain minerals to metabolize oil. They are able to attack the oil best when it is mixed with water. Even highway blacktop gets eaten in time, but its dryness, the lack of minerals such as nitrogen and the large size of the asphaltene molecules in blacktop make it tough chewing for the bugs.

Many hydrocarbons dissolve only slowly in water. Others such as the aromatic compounds like benzene are more soluble, and these are toxic to living cells. The aromatic hydrocarbons can attack the fat-like membranes surrounding cells and adversely affect their normal functioning. But, fortunately, bacteria and other microorganisms composing the marine flora are able to feed upon the wide variety of compounds found in petroleum. The ocean water itself aids the process by helping to transport oxygen and minerals to the microorganisms.

By genetic engineering scientists have the means to enhance the capabilities of bacteria to metabolize petroleum, and there have been attempts to develop an oil-eating "super bug." However, even without such assistance, the oceans have a high capacity to biodegrade petroleum. Recently under the T-3 Ice Island in the Arctic Ocean we found active hydrocarbon degradation underway even during the cold and darkness of January. Thus it seems the principal cure for oil pollution is almost everywhere in the oceans, and it has been with us for quite some time.