Thursday, May 12, 2011
Evolution happens even within a human lifetime
Nylon is a synthetic material and was invented in 1935. Bacteria cannot grow/feed on synthetics. However, in 1975 Japanese scientists discovered a new bacteria feeding off nylon waste in a pond near a nylon producing factory. The bacteria strain of Flavobacterium, using an enzyme called nylonase, had evolved junk, repetitive DNA to digest certain byproducts of nylon 6 manufacture, such as the linear dimer of 6-aminohexanoate, even though those substances are not known to have existed prior to the invention of nylon. Further study revealed that the three enzymes the bacteria were using to digest the byproducts were significantly different from any other enzymes produced by other Flavobacterium strains (or any other bacteria for that matter), and not effective on any material other than the manmade nylon byproducts.
Scientists have also been able to induce another species of bacteria, Pseudomonas aeruginosa, to evolve the capability to break down the same nylon byproducts in a laboratory by forcing them to live in an environment with no other source of nutrients. The P. aeruginosa strain did not seem to use the same enzymes that had been utilized by the original Flavobacterium strain.
Nylon eating bacteria is an example of evolution working even with a human lifetime.