Nylon-eating bacteria
In 1975 a team of Japanese scientists discovered a strain of Flavobacterium living in ponds containing waste water from a factory producing nylon that was capable of digesting certain byproducts of nylon-6 manufacture, such as, 6-aminohexanoate linear dimer, even though those byproducts had not existed prior to the invention of nylon in 1935. Further study revealed that the three enzymes the bacteria were using to digest the byproducts were novel, significantly different than any other enzymes produced by other Flavobacterium strains (or any other bacteria for that matter), and not effective on any other material other than the man made nylon byproducts. This strain of Flavobacterium, Sp. K172, became popularly known as nylon eating bacteria, and the enzymes were collectively known as nylonase.
Further research
Scientists were able to induce another species of bacteria, Pseudomonas, 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 Pseudomonas strain did not seem to use the same enzymes that had been utilized by the original Flavobacterium strain. Other scientists were able to get the ability to generate the enzymes to transfer from the Flavobacterium strain to a strain of E.Coli bacteria via a plasmid transfer. Genetic analysis of the plasmid lead some scientists to the conclusion that the genes to produce one of the enzymes had most likely resulted from the combination of a gene duplication event with a frame shift mutation. Further analysis has led to speculation that the fact that the frame shift was able to produce a functioning enzyme was related to the absence of stop codons in the duplicate gene. Research has continued in the hope of better understanding the mechanisms involved in the evolution of new enzymes, and because of the possible importance of bacteria that can metabolize man made molecules to toxic waste cleanup.
Role in creation-evolution controversy
Nylon eating bacteria have been widely discussed in the context of the creation-evolution controversy. Organizations critical of creationism and intelligent design, such as the National Center for Science Education, and New Mexicans for Science and Reason (NMSR) have made extensive references to this research in postings on their websites, arguing that this research refutes claims made by creationists and intelligent design proponents, specifically, the statement that random mutation and natural selection can never add new information to a genome, and the statement that the odds against a useful new protein such as an enzyme arising through a process of random mutation would be prohibitively high.[1] [2]Creationists have disputed these conclusions, often citing analysis posted on the Answers in Genesis website that says that this phenomenon was evidence that plasmids in bacteria were a designed feature intended to allow bacteria to adapt easily to new food sources or cope with toxic chemicals.[3] NMSR, among others, has responded by saying that gene duplication and frame shift mutations were powerful sources of random mutation.[4]
References
- Kinoshita, S., Kageyama, S., Iba, K., Yamada, Y. and Okada, H., Utilization of a cyclic dimer and linear oligomers of ε-aminocapronoic acid by Achromobacter guttatus K172, Agric. Biol. Chem. 116, 547-551 (1981), FEBS 1981
- Yomo, T., Urabe, I. and Okada, H., No stop codons in the antisense strands of the genes for nylon oligomer degradation, Proceedings of the National Academy of Sciences USA 89:3780–3784, 1992
- IRFAN D. PRIJAMBADA, SEIJI NEGORO, TETSUYA YOMO, AND ITARU URABE, Emergence of Nylon Oligomer Degradation Enzymes in Pseudomonas aeruginosa PAO through Experimental Evolution PDF, APPLIED AND ENVIRONMENTAL MICROBIOLOGY, May 1995
- Susumu Ohno, Birth of a unique enzyme from an alternative reading frame of the preexisted, internally repetitious coding sequence, Proc. Natl. Acad. Sci. USA Vol. 81, pp. 2421-2425, April 1984
- Negoro S, Taniguchi T, Kanaoka M, Kimura H, Okada H. Plasmid-determined enzymatic degradation of nylon oligomers. Journal of Bacteriology. July 1983