Nylon-eating bacteria

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Nylon-eating bacteria
Scientific classification edit
Domain: Bacteria
Phylum: Bacteroidetes
Class: Flavobacteriia
Order: Flavobacteriales
Family: Flavobacteriaceae
Genus: Flavobacterium
F. sp. K172
Binomial name
Flavobacterium sp. K172

Nylon-eating bacteria are a strain of Flavobacterium (more recently categorized as Arthrobacter) that can digest certain by-products of nylon 6 manufacture.[1] This strain of Flavobacterium sp. K172, became popularly known as nylon-eating bacteria, and the enzymes used to digest the man-made molecules became popularly known[2] as nylonase.


Chemical structure of 6-aminohexanoic acid

In 1975, a team of Japanese scientists discovered a strain of Flavobacterium, living in ponds containing waste water from a nylon factory, that could digest certain byproducts of nylon 6 manufacture, such as the linear dimer of 6-aminohexanoate. These substances are not known to have existed before the invention of nylon in 1935.

Further study[clarification needed (In the same paper, as implied by the position of the reference note?)] revealed that the three enzymes that the bacteria were using to digest the byproducts were significantly different from any other enzymes produced by any other bacteria, and not effective on any material other than the manmade nylon byproducts.[3]

Later research[edit]

This discovery led geneticist Susumu Ohno in a paper published in April 1984 to speculate that the gene for one of the enzymes, 6-aminohexanoic acid hydrolase, had come about from the combination of a gene duplication event with a frameshift mutation.[4] Ohno suggested that many unique new genes have evolved this way.

A 2007 paper that described a series of studies by a team led by Seiji Negoro of the University of Hyogo, Japan, suggested that in fact no frameshift mutation was involved in the evolution of the 6-aminohexanoic acid hydrolase.[5] However, many other genes have been discovered which did evolve by gene duplication followed by a frameshift mutation affecting at least part of the gene.[citation needed]

A 1995 paper showed that scientists have also been able to induce another species of bacterium, 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.[6]

As described in a 1983 publication, 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.[7]

Role in evolution teaching[edit]

There is scientific consensus that the capacity to synthesize nylonase most probably developed as a single-step mutation that survived because it improved the fitness of the bacteria possessing the mutation. More importantly, the enzyme involved was produced by a mutation completely randomizing the original gene. Despite this, the new gene still had a novel, albeit weak, catalytic capacity. This is seen as a good example of how mutations easily can provide the raw material for evolution by natural selection.[8][9][10][11]

See also[edit]


  1. ^ Takehara, I; Fujii, T; Tanimoto, Y (Jan 2018). "Metabolic pathway of 6-aminohexanoate in the nylon oligomer-degrading bacterium Arthrobacter sp. KI72: identification of the enzymes responsible for the conversion of 6-aminohexanoate to adipate". Applied Microbiology and Biotechnology. 102 (2): 801–814. doi:10.1007/s00253-017-8657-y. PMID 29188330.
  2. ^ Michael Le Page (March 2009). "Five classic examples of gene evolution". New Scientist.
  3. ^ Kinoshita, S.; Kageyama, S.; Iba, K.; Yamada, Y.; Okada, H. (1975). "Utilization of a cyclic dimer and linear oligomers of e-aminocaproic acid by Achromobacter guttatus". Agricultural and Biological Chemistry. 39 (6): 1219–23. doi:10.1271/bbb1961.39.1219. ISSN 0002-1369.
  4. ^ Ohno S (April 1984). "Birth of a unique enzyme from an alternative reading frame of the preexisted, internally repetitious coding sequence". Proc Natl Acad Sci USA. 81 (8): 2421–5. Bibcode:1984PNAS...81.2421O. doi:10.1073/pnas.81.8.2421. PMC 345072. PMID 6585807.
  5. ^ Negoro S, Ohki T, Shibata N, et al. (June 2007). "Nylon-oligomer degrading enzyme/substrate complex: catalytic mechanism of 6-aminohexanoate-dimer hydrolase". J. Mol. Biol. 370 (1): 142–56. doi:10.1016/j.jmb.2007.04.043. PMID 17512009.
  6. ^ Prijambada ID, Negoro S, Yomo T, Urabe I (May 1995). "Emergence of nylon oligomer degradation enzymes in Pseudomonas aeruginosa PAO through experimental evolution". Appl. Environ. Microbiol. 61 (5): 2020–2. PMC 167468. PMID 7646041.
  7. ^ Negoro S, Taniguchi T, Kanaoka M, Kimura H, Okada H (July 1983). "Plasmid-determined enzymatic degradation of nylon oligomers". J. Bacteriol. 155 (1): 22–31. PMC 217646. PMID 6305910.
  8. ^ Thwaites WM (Summer 1985). "New Proteins Without God's Help". Creation Evolution Journal. 5 (2): 1–3.
  9. ^ Evolution and Information: The Nylon Bug
  10. ^ Why scientists dismiss 'intelligent design', Ker Than, MSNBC, Sept. 23, 2005
  11. ^ Miller, Kenneth R. Only a Theory: Evolution and the Battle for America's Soul (2008) pp. 80-82