Bacteria Working in the Shadows: Pseudomonas putida
Ads for commercial cleansers portray bacteria as ominous globs lingering in the darkened corners of our homes. Yet some strains of bacteria actually aid in greening our environment.
“Slick Willy,” or Pseudomonas putida, are gram-negative, rod-shaped bacterium that play a role in decomposition. Bioengineered by professor Ananda M. Chakrabarty in 1971, P. putida was the first patented organism in the world. Coveted for its diverse metabolism — including the ability to break down organic solvents like toluene, benzene and ethylbenzene — Pseudomonas is used in bioremediation, fuel purification and the conversion of styrene into biodegradable plastic. It is also used in industrial products like paint thinners, adhesives and sealants.
A strain of Pseudomonas, the Jan Brady of the Slick Willy family, Pseudomonas aeruginosa, is potentially fatal to humans and animals, and is the most common bacteria to cause fatal infections in hospitals. P. aeruginosa is mainly used in the decomposition of hydrocarbons, tar balls and oil from major drilling blunders (which in themselves are harmful to humans). Pseudomonas aeruginosa secretes a nontoxic, biodegradable protein called rhamnolipid — a soap-like biosurfactant that removes oil pollution in ocean water.
Unfortunately, other oil-eating bacteria, like Alcanivorax and Cycloclasticus, prevent Pseudomonas aeruginosa from doing its job properly. These alkane-digesting bacteria deplete oil-affected areas of the oxygen and nutrients Pseudomonas needs for its metabolism. The battle for nutrients can mean the difference of weeks in oil-spill clean-up and can create anaerobic zones in water — ultimately destroying the ocean’s natural oxygen balance.
Despite the destruction, Pseudomonas remains part of a veritable Justice League of global-friendly bacteria — which Methylokorus infernorum used in combating methane emissions and Rhodococcus erythropolis used to create less polluting fuels.