Melanin Production by Rhizobium Strains

Abstract

Different Rhizobium and Bradyrhizobium strains were screened for their ability to produce melanin. Pigment producers (Mel') were found among strains of R. leguminosarum biovars viceae, trifolii, and phaseoli, R. meliloti, and R. fredii; none of 19 Bradyrhizobium strains examined gave a positive response. Melanin production and nod genes were plasmid borne in R. leguminosarum biovar trifolii RS24. In R. leguminosarum biovar phaseoli CFN42 and R. meliloti GRO15, mel genes were located in the respective symbiotic plasmids. In R. fredii USDA205, melanin production correlated with the presence of its smallest indigenous plasmid. * Corresponding author. Wild type, Mel+* Spontaneous Rif' derivative of RS24, Mel' Kmr derivative of RS240 by insertion of transposon TnS-Mob, Mel' Kanamycin-sensitive derivative of RS2400 after treatment with acridine orange, Mel-Kanamycin-sensitive derivative of RS2400 after treatment with acridine orange, Mel+ Kanamycin-sensitive derivative of RS2400 after treatment with acridine orange, Mel' Wild type, Mel+* Wild type, Mel-Nonnodulating derivative of RS169 after treatment with acridine orange, Mel-Spontaneous Stri derivative of RS169-NA545, Mel-RS169-NA4(pJERS1) (from cross RS2400 x RS169-NA4), Mel+* Wild type, Mel' 128C53 str-279 (ApRL6JI), Mel-Spontaneous Rif' derivative of B151, Mel-B1511(p42d) (from cross A. tumefaciens C58C1 x B1511), Mel+ B1511(p42d) (from cross A. tumefaciens C58C1 x B1511), Mel Wild type, Mel+ Wild type, Mel+ Spontaneous Rif' derivative of strain GRO15, Mel+* Kmr derivatives of TC281 by insertion of transposon Tn5-Mob into pRmeGRO15, pJB3JI, Mel+ Wild type, Mel+ Wild type, Mel' Wild type, Mel+* Spontaneous Rif derivative of strain USDA205, Mel-Spontaneous Rifr derivative of strain USDA205, Mel-Spontaneous Strr derivative of strain USDA205, Mel+* AB55(R68.45) (from cross E. cOli 1230 x AB55), Mel+ Spontaneous Rif derivative of strain USDA205, Mel+* Kmr transconjugants of AB034 by transposon TnS-Mob mutagenesis, Mel-Wild type, Mel+* Wild type, Mel+* Wild type, Mel+* Rif' Strr Mel-Spontaneous CM' derivative of strain GM19023, Mel AB274(pJERS1) (from cross RS2400 x AB274), Mel+* AB274(pTC1) (from cross TC282 x AB274), Mel' AB274(pTC2) (from cross TC283 x AB274), Mel' AB274(pTC3) (from cross TC284 x AB274), Mel' Eryr Cmlr pTi-cured derivative of A. tumefaciens C58, Mel-C58C1(p42d), Mel't 294 Rec-, chromosomally integrated RP4 derivative, Tpr Strr Pro-Met-Nalr (R68.45) Pro-Met-Nalr (pJB3JI) hsdS hsdM pro leu thi gal lac Y recA Strr pBR325;:TnS-Mob Used for mobilizing plasmids, Kmr P1 group R-plasmids: Apr Kmr Tcr R68.45 Kms, used for mobilizing plasmids 220-MDa indigenous plasmid of R. leguminosarum biovar trifolii RS24; Mel+ Co

Laccase activity in melanin-producing strains ofSinorhizobium meliloti

“…Strains were maintained in TY medium. Melanin production was obtained by growing cells in TY medium supplemented with 600 μg ml −1 l ‐tyrosine and 40 μg ml −1 CuSO 4 [19].…”

Melanosomes and ancient coloration re‐examined: A response to Vinther 2015 (DOI 10.1002/bies.201500018)

“…Melanin is not well characterized chemically , but certain breakdown products can be identified that are causally linked to this biochrome. However, melanin is also produced by microbes , so microbial melanin(s) arising from bacteria and fungi should be characterized and eliminated as a possibility. Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) is a powerful tool for melanosome investigation, because it can be conducted in situ on fossil samples, and can identify patterns consistent with melanin and map them to fossil microbodies ; however, this method is sensitive to surface and preparation artefacts.…”

“…Melanin, a ubiquitous biochrome, has photoprotective and antibacterial functions . Intriguingly, some microorganisms produce this biochrome , whereas others are efficient at breaking it down to use as a carbon source . Porphyrin, a well‐characterized biochrome, forms the functional units of hemoglobin, cytochrome, and chlorophyll; chlorophyll, one of the oldest biochromes , is the site of photosynthesis.…”

Laccase activity in melanin-producing strains of Sinorhizobium meliloti

“…Strains were maintained in TY medium. Melanin production was obtained by growing cells in TY medium supplemented with 600 Wg ml 31 L-tyrosine and 40 Wg ml 31 CuSO 4 [19].…”