National Academy of Agricultural Sciences (NAAS)
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PRINT ISSN : 2319-7692
Online ISSN : 2319-7706 Issues : 12 per year Publisher : Excellent Publishers Email : editorijcmas@gmail.com / submit@ijcmas.com Editor-in-chief: Dr.M.Prakash Index Copernicus ICV 2018: 95.39 NAAS RATING 2020: 5.38 |
There is growing interest in the use of natural pigments for a wide range of applications. A search for pigment-producing bacteria led to the isolation of a marine bacterium that produced a diffusible brown pigment. The bacterium was identified as Acinetobacter spp.from 16S rRNA gene sequencing. The pigment displayed free-radical scavenging activity and was characterized as a melanin through solubility tests, UV-Vis spectrophotometry and Fourier transform infrared (FTIR) spectroscopy. Melanin production was blocked by sulcotrione, an inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD), the enzyme responsible for producing homogentisic acid (HGA), which is the monomeric precursor of pyomelanin. Inactivation of melanin synthesis by HPPD inhibition confirmed that the pigment was pyomelanin. Acinetobacter spp. required at least 12 days to produce approximately 1g/L of pyomelanin when it was grown in basal medium supplemented with L-tyrosine. The rate of pyomelanin production was not influenced by nutrient levels in growth media. Supplementation with different carbon sources and the use of nutrient-rich media had no effect in accelerating pigment production. However, pH had a major effect on pyomelanin formation by significantly reducing the time taken to produce the pigment. When the pH of growth medium (pH 5.5) was adjusted to pH 8, bacteria were able to produce pyomelanin in 7 days instead of 12-14 days.
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