Nylon-eating bacteria | |
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Scientific classification | |
Domain: | Bacteria |
Phylum: | Actinomycetota |
Class: | Actinomycetia |
Order: | Micrococcales |
Family: | Micrococcaceae |
Genus: | Paenarthrobacter |
Species: | |
Variety: | P. u. var. KI72 |
Trinomial name | |
Paenarthrobacter ureafaciens var. KI72 GTDB r95 & NCBI, 2020 (Busse HJ, 2016) | |
Synonyms | |
(Due to an OCR error, the strain name has occasionally been reported as "K172".) Contents |
Paenarthrobacter ureafaciens KI72, popularly known as nylon-eating bacteria, is a strain of Paenarthrobacter ureafaciens that can digest certain by-products of nylon 6 manufacture. [2] It uses a set of enzymes to digest nylon, popularly known as nylonase. [3]
In 1975, a team of Japanese scientists discovered a strain of bacterium, 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. It was initially named as Achromobacter guttatus. [4]
Studies in 1977 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. [5]
The bacterium was reassigned to Flavobacterium in 1980. [6] Its genome was resolved in 2017, again reassigning it to Arthrobacter . [1] The Genome Taxonomy Database considers it a strain of Paenarthrobacter ureafaciens following a 2016 reclassification. [7] As of January 2021, the NCBI taxonomy browser has been updated to match GTDB.
A few newer strains have been created by growing the original KI72 in different conditions, forcing it to adapt. These include KI722, KI723, KI723T1, KI725, KI725R, and many more. [8]
The bacterium contains the following three enzymes:
All three enzymes are encoded on a plasmid called pOAD2. [9] The plasmid can be transferred to E. coli , as shown in a 1983 publication. [10]
The enzyme EI is related to amidases. Its structure was resolved in 2010. [11]
EII has evolved by gene duplication followed by base substitution of another protein EII'. Both enzymes have 345 identical aminoacids out of 392 aminoacids (88% homology). The enzymes are similar to beta-lactamase. [12]
The EII' (NylB', P07062 ) protein is about 100x times less efficient compared to EII. A 2007 research by the Seiji Negoro team shows that just two amino-acid alterations to EII', i.e. G181D and H266N, raises its activity to 85% of EII. [9]
The structure of EIII was resolved in 2018. Instead of being a completely novel enzyme, it appears to be a member of the N-terminal nucleophile (N-tn) hydrolase family. [13] Specifically, computational approaches classify it as a MEROPS S58 (now renamed P1) hydrolase. The protein is expressed as a precursor, which then cleaves itself into two chains. [14] [15] Outside of this plasmid, > 95% similar proteins are found in Agromyces and Kocuria . [13]
EIII was originally thought to be completely novel. Susumu Ohno proposed that it had come about from the combination of a gene-duplication event with a frameshift mutation. An insertion of thymidine would turn an arginine-rich 427aa protein into this 392aa enzyme. [16]
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, one of the enzymes involved was produced by a frame-shift mutation that completely scrambled existing genetic code data. [17] 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. [18] [19] [20] [21]
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. [22]
Escherichia coli ( ESH-ə-RIK-ee-ə KOH-ly) is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms. Most E. coli strains are harmless, but some serotypes such as EPEC, and ETEC are pathogenic and can cause serious food poisoning in their hosts, and are occasionally responsible for food contamination incidents that prompt product recalls. Most strains are part of the normal microbiota of the gut and are harmless or even beneficial to humans (although these strains tend to be less studied than the pathogenic ones). For example, some strains of E. coli benefit their hosts by producing vitamin K2 or by preventing the colonization of the intestine by pathogenic bacteria. These mutually beneficial relationships between E. coli and humans are a type of mutualistic biological relationship — where both the humans and the E. coli are benefitting each other. E. coli is expelled into the environment within fecal matter. The bacterium grows massively in fresh fecal matter under aerobic conditions for three days, but its numbers decline slowly afterwards.
Mycobacterium leprae is one of the two species of bacteria that cause Hansen’s disease (leprosy), a chronic but curable infectious disease that damages the peripheral nerves and targets the skin, eyes, nose, and muscles.
In molecular biology and genetics, transformation is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane(s). For transformation to take place, the recipient bacterium must be in a state of competence, which might occur in nature as a time-limited response to environmental conditions such as starvation and cell density, and may also be induced in a laboratory.
In materials science and molecular biology, thermostability is the ability of a substance to resist irreversible change in its chemical or physical structure, often by resisting decomposition or polymerization, at a high relative temperature.
Pseudomonas citronellolis is a Gram-negative, bacillus bacterium that is used to study the mechanisms of pyruvate carboxylase. It was first isolated from forest soil, under pine trees, in northern Virginia, United States.
In enzymology, a limonene-1,2-epoxide hydrolase (EC 3.3.2.8) is an enzyme that catalyzes the chemical reaction
Aryldialkylphosphatase is a metalloenzyme that hydrolyzes the triester linkage found in organophosphate insecticides:
In enzymology, a 6-aminohexanoate-cyclic-dimer hydrolase (EC 3.5.2.12) is an enzyme that catalyzes the chemical reaction
In enzymology, a 6-aminohexanoate-dimer hydrolase (EC 3.5.1.46) is an enzyme that catalyzes the chemical reaction N-(6-aminohexanoyl)-6-aminohexanoate + H2O 2 6-aminohexanoate. Thus, the two substrates of this enzyme are N-(6-aminohexanoyl)-6-aminohexanoate and H2O, whereas its product is two molecules of 6-aminohexanoate.
60S ribosomal protein L11 is a protein that in humans is encoded by the RPL11 gene.
The discovery of nylon-eating bacteria has been used to educate and challenge creationist arguments against evolution and natural selection. These bacteria can produce novel enzymes that allow them to feed on by-products of nylon manufacture which did not exist prior to the invention of nylon in the 1930s. Observation of these adaptations refute religious and pseudoscientific claims that no new information can be added to a genome and that proteins are too complex to evolve through a process of mutation and natural selection. Apologists have produced reactionary literature attempting to deny that evolution occurs, in turn generating input from the scientific community.
A prokaryote is a single-cell organism whose cell lacks a nucleus and other membrane-bound organelles. The word prokaryote comes from the Ancient Greek πρό 'before' and κάρυον 'nut, kernel'. In the two-empire system arising from the work of Édouard Chatton, prokaryotes were classified within the empire Prokaryota. But in the three-domain system, based upon molecular analysis, prokaryotes are divided into two domains: Bacteria and Archaea. Organisms with nuclei are placed in a third domain, Eukaryota.
Plasmid-mediated resistance is the transfer of antibiotic resistance genes which are carried on plasmids. Plasmids possess mechanisms that ensure their independent replication as well as those that regulate their replication number and guarantee stable inheritance during cell division. By the conjugation process, they can stimulate lateral transfer between bacteria from various genera and kingdoms. Numerous plasmids contain addiction-inducing systems that are typically based on toxin-antitoxin factors and capable of killing daughter cells that don't inherit the plasmid during cell division. Plasmids often carry multiple antibiotic resistance genes, contributing to the spread of multidrug-resistance (MDR). Antibiotic resistance mediated by MDR plasmids severely limits the treatment options for the infections caused by Gram-negative bacteria, especially family Enterobacteriaceae. The global spread of MDR plasmids has been enhanced by selective pressure from antimicrobial medications used in medical facilities and when raising animals for food.
Arabinogalactan endo-β-1,4-galactanase is an enzyme with systematic name arabinogalactan 4-β-D-galactanohydrolase. It specifically catalyses the hydrolysis (1→4)-β-D-galactosidic linkages in type I arabinogalactans.
Acidobacterium capsulatum is a bacterium. It is an acidophilic chemoorganotrophic bacterium containing menaquinone. It is gram-negative, facultative anaerobic, mesophilic, non-spore-forming, capsulated, saccharolytic and rod-shaped. It is also motile by peritrichous flagella. Its type strain is JCM 7670.
Cyclic di-AMP is a second messenger used in signal transduction in bacteria and archaea. It is present in many Gram-positive bacteria, some Gram-negative species, and archaea of the phylum euryarchaeota.
Paenarthrobacter ureafaciens is a bacterial species of the genus Paenarthrobacter. Polar lipid profile of this species is an unknown.
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Cytophaga hutchinsonii is a bacterial species in the genus Cytophaga. C. hutchinsonii is an aerobic, gram-negative, soil, microorganism that exhibits gliding motility, enabling it to move quickly over surfaces and is capable of cellulose degradation.
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