Optimum melanin production using recombinant Escherichia coli

Lagunas-Muñoz, Victor H.; Cabrera-Valladares, Natividad; Bolívar, Francisco; Gosset, Guillermo; Martı́nez, Alfredo

doi:10.1111/j.1365-2672.2006.03013.x

Cited by 63 publications

(69 citation statements)

References 33 publications

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“…Using a partially purified MelA tyrosinase, Cabrera-Valladares et al found that the pH optimum for the enzyme's L-DOPA oxidase activity lies in the range of 6.5 to 7.5 (7). Subsequent optimization of melanin production in stationary-phase E. coli cultures revealed a pH optimum of 7.5 (13).…”

Section: Resultsmentioning

confidence: 99%

“…The coupling of L-tyrosine production and melanin synthesis thus enables a simple method for identifying high L-tyrosine producers within a mixed population of cells. In the present study, we have introduced the melA gene from Rhizobium etli (7,13) into a series of E. coli L-tyrosine production strains. Strains that either produced or were exposed to greater amounts of L-tyrosine could be distinguished by the unique pigmentation imparted by the synthesis of melanin.…”

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confidence: 99%

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Melanin-Based High-Throughput Screen for l -Tyrosine Production in Escherichia coli

Santos

Stephanopoulos

2008

Appl Environ Microbiol

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Escherichia coli with the synthesis of the black and diffusible pigment melanin. Although melanin was initially produced only at low levels in morpholinepropanesulfonic acid (MOPS) minimal medium, phosphate supplementation was found to be sufficient for increasing both the rates of synthesis and the final titers of melanin. Furthermore, a strong linear correlation between extracellular L-tyrosine content and melanin formation was observed by use of this new medium formulation. A selection strategy that utilizes these findings has been developed and has been shown to be effective in screening large combinatorial libraries in the search for L-tyrosine-overproducing strains.Traditional metabolic engineering has often focused on the rational design of metabolic pathways, relying on extensive a priori knowledge of cellular mechanisms in order to redirect metabolite flow, revise metabolic regulation, or introduce new pathways to achieve a particular phenotype (3). In recent years, however, considerable advances in molecular biology and the growing availability of annotated genome sequences have made combinatorial methods of metabolic engineering an increasingly attractive approach for strain improvement. With these search strategies, random, traceable genetic-level perturbations are introduced into a cell to yield a new population of strains with a diverse range of properties. A screen is then implemented in order to probe these mutant libraries for strains exhibiting enhancements in the trait of interest. Although the potential of the combinatorial approach has already been demonstrated for a number of genetic tools, including transposon mutagenesis, genomic complementation, and global transcription machinery engineering (1, 12), each of these examples has dealt with easily accessible phenotypes. In the case of lycopene production in Escherichia coli, desirable clones assumed a red pigmentation and could therefore be selected by visual inspection. For solvent (sodium dodecyl sulfate, ethanol) tolerance in E. coli and Saccharomyces cerevisiae, simple growth competition assays were used to heavily enrich a population with the best performers. For most other systems of interest, however, the widespread use of these combinatorial approaches is hampered by the absence of a high-throughput method for selecting strains with the desired cellular properties.Although L-tyrosine has received far less attention than the other aromatic amino acids, L-tryptophan and L-phenylalanine, it remains a valuable target compound for microbial production. Apart from its use as a dietary supplement, L-tyrosine also serves as a precursor for 3,4-dihydroxy-L-phenylalanine (L-DOPA, or levodopa), an important drug for the treatment of Parkinson's disease (5). Additionally, L-tyrosine is involved in the synthesis of p-hydroxycinnamic acid and p-hydroxystyrene, both of which serve as starting materials for a variety of novel polymers, adhesives and coatings, pharmaceuticals, biocosmetics, and health and nutrition products (20,23).Most prior work o...

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Melanin-Based High-Throughput Screen for l -Tyrosine Production in Escherichia coli

Santos

Stephanopoulos

2008

Appl Environ Microbiol

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“…The Legionella genus contains 51 species besides L. pneumophila, and 20 of these species have been shown to cause disease (34,37,56,59,76). Although not all Legionella species produce brown pigmentation when grown on tyrosine-containing media (34), limited testing indicates a correlation between melanin production and the presence of lly (10,34 (1,4,24,25,33,42,44,45,48,55,58,63,64,70,75,77,79,90,100,102,110,111,115). Within this group, a variety of melanins are produced, including black and brown eumelanins, yellow-red pheomelanins, and brown allomelanins, which have as subsets the brown pyomelanins (HGA-melanin) and the black di/tetrahydroxynaphthelene melanins (71,79,110).…”

Section: Discussionmentioning

confidence: 99%

“…Although some Legionella studies have monitored pigment production using 550 nm (5,66,112,116), we found that the difference in absorbance between wild-type supernatants and pigment null mutant supernatants is more easily seen at the lower wavelength (see below). Additionally, studies examining similarly colored pigments in other bacteria routinely use wavelengths at or just below 400 nm (58,90,102,115).…”

Section: Methodsmentioning

confidence: 99%

The Secreted Pyomelanin Pigment of Legionella pneumophila Confers Ferric Reductase Activity

2007

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The virulence of Legionella pneumophila is dependent upon its capacity to acquire iron. To identify genes involved in expression of its siderophore, we screened a mutagenized population of L. pneumophila for strains that were no longer able to rescue the growth of a ferrous transport mutant. However, an unusual mutant was obtained that displayed a strong inhibitory effect on the feoB mutant. Due to an insertion in hmgA that encodes homogentisate 1,2-dioxygenase, the mutant secreted increased levels of pyomelanin, the L. pneumophila pigment that is derived from secreted homogentisic acid (HGA). Thus, we hypothesized that L. pneumophilasecreted HGA-melanin has intrinsic ferric reductase activity, converting Fe 3؉ to Fe 2؉ , but that hyperpigmentation results in excessive reduction of iron that can, in the case of the feoB mutant, be inhibitory to growth. In support of this hypothesis, we demonstrated, for the first time, that wild-type L. pneumophila secretes ferric reductase activity. Moreover, whereas the hyperpigmented mutant had increased secreted activity, an lly mutant specifically impaired for pigment production lacked the activity. Compatible with the nature of HGA-melanins, the secreted ferric reductase activity was positively influenced by the amount of tyrosine in the growth medium, resistant to protease, acid precipitable, and heterogeneous in size. Together, these data represent the first demonstration of pyomelanin-mediated ferric reduction by a pathogenic bacterium.Legionella pneumophila, an occupant of natural and humanmade aquatic environments, is also the principal agent of Legionnaires' disease, a serious form of pneumonia that especially afflicts immunocompromised individuals (18,37,41). In water habitats, this gram-negative bacterium survives free, in biofilms, and as an intracellular parasite of protozoa (2, 62, 65); in the lung, it replicates in alveolar macrophages (67,93,95). Among the processes that promote L. pneumophila growth in both the environment and the mammalian host are Lsp type II protein secretion, Dot/Icm type IVB protein secretion, and the Lvh type IVA protein secretion system (8,19,27,57,84,105). Other notable surface features of L. pneumophila include flagella, type IV pili, the major outer membrane protein porin, the Hsp60 chaperonin, and the Mip peptidylproline isomerase (9,26,39,46,49,66,88,99,108). In addition to exporting proteins and enzymes onto its surface or into the extracellular milieu and/or host cells, L. pneumophila also secretes a siderophore (legiobactin) that promotes iron uptake (3). Iron acquisition has long been regarded as a key aspect of L. pneumophila growth, intracellular infection, and virulence (12,17,82). Besides legiobactin, we have uncovered both FeoB ferrous iron transport, which is critical for bacterial growth in host cells and the lung, as well as the ccm, frgA, hbp, iraAB, and tat genes, which also promote L. pneumophila growth under low-iron conditions (20,47,68,73,81,86,87,106,107). The discovery of legiobactin has drawn further attention...

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“…Escherichia coli is firstly used for producing melanin (Lagunas-Muñoz et al, 2006). However, some hidden troubles and potential dangers still exist during fermentation process of E. coli.…”

Section: Introductionmentioning

confidence: 99%

Optimization of culture medium for production of melanin by Auricularia auricula

Zou

Hou

2017

Food Sci. Technol

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Melanin is a natural high molecular weight pigment with the huge application value and development potential in food industry. In the present study, medium composition for melanin production by fungus Auricularia auricula was investigated. Wheat bran extract, l-tyrosine, and CuSD 4 were determined to optimize medium composition by response surface methodology with Box-Behnken design. Results indicated that the optimal medium composition was 26.80% (v/v) wheat bran extract, 1.59 g/L l-tyrosine, and 0.11 g/L CuSD 4 , and the maximum melanin yield was 519.54 mg/L. Melanin production through A. auricula fermentation avoided expensive enzymatic or complicated chemical methods for melanin extraction from tissues of plant or animal, which had the huge application value and development potential for efficient production of melanin.Keywords: optimization; culture medium; melanin; Auricularia auricula.Practical Application: Melanin production through A. auricula fermentation is a new preparation method of melanin.

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Optimum melanin production using recombinant Escherichia coli

Cited by 63 publications

References 33 publications

Melanin-Based High-Throughput Screen for l -Tyrosine Production in Escherichia coli

Melanin-Based High-Throughput Screen for l -Tyrosine Production in Escherichia coli

The Secreted Pyomelanin Pigment of Legionella pneumophila Confers Ferric Reductase Activity

Optimization of culture medium for production of melanin by Auricularia auricula

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