Re-appraisal of the nature of the pigment produced by<i>Aeromonas salmonicida</i>

Donlon, John; McGettigan, Seán; O’Brien, Paul; Carra, Pádraig Ó

doi:10.1111/j.1574-6968.1983.tb00558.x

Cited by 14 publications

(4 citation statements)

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“…Although we demonstrated that pyomelanin is the major melanin constituent in A. media strain WS recently (Wang et al, 2015), many Aeromonas strains have also been proposed to produce DOPA-melanin, since the characteristic intermediate L-DOPA could be detected from the culture fluids of several melanogenic Aeromonas strains (Aurstad and Dahle, 1972; Donlon et al, 1983; Gibson and George, 1998; Wan et al, 2007). Here, we confirmed that DOPA-melanin was produced in A. media strain WS, although it was not a major contributor to pigmentation.…”

Section: Discussionmentioning

confidence: 84%

“…It is important to note, though, that the melanin is also synthesized by the DOPA-based pathway in many Aeromonas species, if not all of them. This conclusion is based on the detection of the characteristic intermediate L-DOPA in several melanogenic Aeromonas strains (Aurstad and Dahle, 1972; Donlon et al, 1983; Gibson and George, 1998; Wan et al, 2007). The conclusion is further supported as proteins unrelated to the HGA pathway regulate melanogenesis in Aeromonas , albeit by unknown mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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Identification of YfiH and the Catalase CatA As Polyphenol Oxidases of Aeromonas media and CatA as a Regulator of Pigmentation by Its Peroxyl Radical Scavenging Capacity

et al. 2017

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Pyomelanin is the major constituent of pigment in melanogenic Aeromonas strains of bacteria. However, eumelanin, synthesized from tyrosine via L-DOPA and polyphenol oxidases (PPOs), may also be present in this genus since L-DOPA is frequently detected in culture fluids of several species. To address this question, we used a deletion mutant of Aeromonas media strain WS, in which pyomelanin synthesis is completely blocked under normal culture conditions. When tyrosine was supplied to the medium, we observed residual melanin accumulation, which we interpret as evidence for existence of the DOPA-melanin pathway. We traced enzymatic activity in this bacterium using native-polyacrylamide gel electrophoresis. Two PPOs: YfiH, a laccase-like protein, and CatA, a catalase, were identified. However, neither protein was critical for the residual pigmentation in pyomelanin-deficient mutant. We speculate that eumelanin synthesis may require other unknown enzymes. Deletion of yfiH did not affect pigmentation in A. media strain WS, while deletion of the CatA-encoding gene katE resulted in a reduction of melanin accumulation, but it started 9 h earlier than in the wild-type. Since catalases regulate reactive oxygen species levels during melanogenesis, we speculated that CatA affects pigmentation through its peroxyl radical scavenging capacity. Consistent with this, expression of the catalases Hpi or Hpii from Escherichia coli in the katE deletion strain of A. media strain WS restored pigmentation to the wild-type level. Hpi and Hpii also exhibited PPO activity, suggesting that catalase may represent a new class of PPOs.

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Section: Discussionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Identification of YfiH and the Catalase CatA As Polyphenol Oxidases of Aeromonas media and CatA as a Regulator of Pigmentation by Its Peroxyl Radical Scavenging Capacity

et al. 2017

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“…2). Despite the fact that melanin synthesis has been reported for several A. salmonicida and A. media strains (1,(46)(47)(48), melanin synthesis pathways have not been elucidated for these bacteria.…”

Section: Melanin Biosynthesis One Of the Most Distinctive Phenotypicmentioning

confidence: 99%

“…The best-known pathway for melanin biosynthesis involves tyrosinases, which produce eumelanins (brown or black) and phaeomelanins (reddish) through the oxidation of tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA) and dopaquinone (49). An early study that investigated melanin-like pigment production in A. salmonicida arrived to the conclusion that the pigment produced differed from eumelanin and phaeomelanin (46).…”

Section: Melanin Biosynthesis One Of the Most Distinctive Phenotypicmentioning

confidence: 99%

Living in an Extremely Polluted Environment: Clues from the Genome of Melanin-Producing Aeromonas salmonicida subsp. pectinolytica 34mel ^T

Paván

Pavan

López

et al. 2015

Appl Environ Microbiol

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d Aeromonas salmonicida subsp. pectinolytica 34mel T can be considered an extremophile due to the characteristics of the heavily polluted river from which it was isolated. While four subspecies of A. salmonicida are known fish pathogens, 34melT belongs to the only subspecies isolated solely from the environment. Genome analysis revealed a high metabolic versatility, the capability to cope with diverse stress agents, and the lack of several virulence factors found in pathogenic Aeromonas. The most relevant phenotypic characteristics of 34mel T are pectin degradation, a distinctive trait of A. salmonicida subsp. pectinolytica, and melanin production. Genes coding for three pectate lyases were detected in a cluster, unique to this microorganism, that contains all genes needed for pectin degradation. Melanin synthesis in 34melT is hypothesized to occur through the homogentisate pathway, as no tyrosinases or laccases were detected and the homogentisate 1,2-dioxygenase gene is inactivated by a transposon insertion, leading to the accumulation of the melanin precursor homogentisate. Comparative genome analysis of other melanogenic Aeromonas strains revealed that this gene was inactivated by transposon insertions or point mutations, indicating that melanin biosynthesis in Aeromonas occurs through the homogentisate pathway. Horizontal gene transfer could have contributed to the adaptation of 34mel T to a highly polluted environment, as 13 genomic islands were identified in its genome, some of them containing genes coding for fitness-related traits. Heavy metal resistance genes were also found, along with others associated with oxidative and nitrosative stresses. These characteristics, together with melanin production and the ability to use different substrates, may explain the ability of this microorganism to live in an extremely polluted environment.A eromonas salmonicida subsp. pectinolytica 34melT is a melanin-producing Aeromonas strain that degrades polypectate, which is an unusual characteristic among Aeromonas species (1). It was isolated from the heavily polluted water of the Riachuelo, the last part of the Matanza River, located in Buenos Aires, Argentina. This river has received the effluents of hundreds of tanneries and other industries, as well as urban sewage and fuels, for more than a century. Among the contaminants found in this environment, which has high organic matter and low dissolved oxygen contents, are hydrocarbons, polychlorinated biphenyls, pesticides, arsenic, and heavy metals, such as chromium, lead, copper, mercury, and nickel (2-4). A molecular analysis of the microbial diversity of river water and sediments from the isolation site showed the presence of bacteria belonging to several taxa. Analysis of 16S rRNA gene sequences revealed the presence of bacteria belonging to the Beta-, Gamma-, and Epsilonproteobacteria in the water, as well as a higher level of diversity in the sediments, in which Alpha-, Beta-, Gamma-, and Deltaproteobacteria, Firmicutes, and Bacteroidetes were detected (5).The ge...

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Aeromonas

Chang¹,

Janda²

2010

Topley &Amp; Wilson's Microbiology and Microbial Infections

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Re-appraisal of the nature of the pigment produced byAeromonas salmonicida

Cited by 14 publications

References 13 publications

Identification of YfiH and the Catalase CatA As Polyphenol Oxidases of Aeromonas media and CatA as a Regulator of Pigmentation by Its Peroxyl Radical Scavenging Capacity

Identification of YfiH and the Catalase CatA As Polyphenol Oxidases of Aeromonas media and CatA as a Regulator of Pigmentation by Its Peroxyl Radical Scavenging Capacity

Living in an Extremely Polluted Environment: Clues from the Genome of Melanin-Producing Aeromonas salmonicida subsp. pectinolytica 34mel ^T

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Re-appraisal of the nature of the pigment produced byAeromonas salmonicida

Cited by 14 publications

References 13 publications

Identification of YfiH and the Catalase CatA As Polyphenol Oxidases of Aeromonas media and CatA as a Regulator of Pigmentation by Its Peroxyl Radical Scavenging Capacity

Identification of YfiH and the Catalase CatA As Polyphenol Oxidases of Aeromonas media and CatA as a Regulator of Pigmentation by Its Peroxyl Radical Scavenging Capacity

Living in an Extremely Polluted Environment: Clues from the Genome of Melanin-Producing Aeromonas salmonicida subsp. pectinolytica 34mel T

Aeromonas

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Living in an Extremely Polluted Environment: Clues from the Genome of Melanin-Producing Aeromonas salmonicida subsp. pectinolytica 34mel ^T