Nylon-eating bacteria
Encyclopedia
Nylon-eating bacteria are a strain of Flavobacterium
Flavobacterium
Flavobacterium is a genus of Gram-negative, non-motile and motile, rod-shaped bacteria that consists of ten recognized species, as well as three newly proposed species . Flavobacteria are found in soil and fresh water in a variety of environments...

that is capable of digesting certain byproducts of nylon 6
Nylon 6
Nylon 6 or polycaprolactam is a polymer developed by Paul Schlack at IG Farben to reproduce the properties of nylon 6,6 without violating the patent on its production. Unlike most other nylons, nylon 6 is not a condensation polymer, but instead is formed by ring-opening polymerization. This makes...

 manufacture. This strain of Flavobacterium, Sp. K172, became popularly known as nylon-eating bacteria, and the enzymes used to digest the man-made molecules became collectively known as nylonase.

Discovery

In 1975 a team of Japanese scientists discovered a strain of Flavobacterium
Flavobacterium
Flavobacterium is a genus of Gram-negative, non-motile and motile, rod-shaped bacteria that consists of ten recognized species, as well as three newly proposed species . Flavobacteria are found in soil and fresh water in a variety of environments...

, living in ponds containing waste water
Wastewater
Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations...

 from a nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...

 factory, that was capable of digesting certain byproducts of nylon 6
Nylon 6
Nylon 6 or polycaprolactam is a polymer developed by Paul Schlack at IG Farben to reproduce the properties of nylon 6,6 without violating the patent on its production. Unlike most other nylons, nylon 6 is not a condensation polymer, but instead is formed by ring-opening polymerization. This makes...

 manufacture, such as the linear dimer of 6-aminohexanoate
Aminocaproic acid
Aminocaproic acid is a derivative and analogue of the amino acid lysine, which makes it an effective inhibitor for enzymes that bind that particular residue. Such enzymes include proteolytic enzymes like plasmin, the enzyme responsible for fibrinolysis...

, even though those substances are not known to have existed before the invention of nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...

 in 1935. Further study revealed that the three enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s the bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 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.

Later research

This discovery led geneticist Susumu Ohno
Susumu Ohno
was an Asian American geneticist and evolutionary biologist, and seminal researcher in the field of molecular evolution.- Biography :Susumu Ohno was born of Japanese parents in Seoul, Korea, on February 1, 1928. The second of five children, he was the son of the minister of education of the...

 to speculate that the gene for one of the enzymes, 6-aminohexanoic acid hydrolase, had come about from the combination of a gene duplication
Gene duplication
Gene duplication is any duplication of a region of DNA that contains a gene; it may occur as an error in homologous recombination, a retrotransposition event, or duplication of an entire chromosome.The second copy of the gene is often free from selective pressure — that is, mutations of it have no...

 event with a frame shift mutation. 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. 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. A 2006 study found 470 examples in humans alone.

Scientists have also been able to induce another species of bacteria, Pseudomonas aeruginosa
Pseudomonas aeruginosa
Pseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...

, 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
Flavobacterium
Flavobacterium is a genus of Gram-negative, non-motile and motile, rod-shaped bacteria that consists of ten recognized species, as well as three newly proposed species . Flavobacteria are found in soil and fresh water in a variety of environments...

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
Plasmid
In microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA. They are double-stranded and, in many cases, circular...

 transfer.

Role in evolution teaching

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. This is seen as a good example of evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

 through mutation and natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

 that has been observed as it occurs.

See also

  • E. coli long-term evolution experiment
    E. coli long-term evolution experiment
    The E. coli long-term evolution experiment is an ongoing study in experimental evolution led by Richard Lenski that has been tracking genetic changes in 12 initially identical populations of asexual Escherichia coli bacteria since 24 February 1988...

  • Radiotrophic fungus
    Radiotrophic fungus
    Radiotrophic fungi are fungi which appear to use the pigment melanin to convert gamma radiation into chemical energy for growth. This proposed mechanism may be similar to anabolic pathways for the synthesis of reduced organic carbon in phototrophic organisms, which capture photons from visible...

  • Evolution
    Evolution
    Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

  • Creation-evolution controversy
    Creation-evolution controversy
    The creation–evolution controversy is a recurring cultural, political, and theological dispute about the origins of the Earth, humanity, life, and the universe....

  • Nylon-eating bacteria and creationism
    Nylon-eating bacteria and creationism
    The discovery of nylon-eating bacteria has been used by critics of creationism and intelligent design, in both print articles and on websites, to challenge creationist claims...

  • London Underground mosquito
    London Underground mosquito
    The London Underground mosquito is a species of mosquito in the genus Culex found in the London Underground. It is thought to have evolved from the overground species Culex pipiens recently. Biologists named the London Underground mosquito Culex pipiens molestus due to its voracious biting. Notably...

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