Production of melanin pigment from Pseudomonas stutzeri isolated from red seaweed Hypnea musciformis

Hypnea musciformis red seaweed is popularly known to produce carrageenan was collected from the Gulf of Mannar, India. Strain HMGM‐7 [MTCC 11712] was isolated from the surface of this seaweed, which was capable of producing an extracellular black‐coloured polymeric pigment. Based on phenotypic characterization and 16S rDNA sequencing, the strain HMGM‐7 was identified as Pseudomonas stutzeri. Biophysical characterization by UV–visible, FT‐IR, EPR and XRD spectroscopic studies confirmed the pigment as melanin. Further chemical characterization showed that it was acid‐resistant, alkali‐soluble and alkali‐insoluble in most of the organic solvents and distilled water. To our knowledge, this is a first report on a marine Pseudomonas stutzeri strain producing significant amounts of melanin of about 6·7 g l−1 without L‐tyrosine supplementation in the sea‐water production medium. Significance and Impact of the Study This investigation reports a marine Pseudomonas stutzeri strain HMGM‐7 [MTCC 11712] that produces significant quantities of melanin (6·7 g l−1) in sea‐water medium without the supplementation of L‐tyrosine. The confirmation of the produced melanin was carried out by various chemical and physical characterization studies. The isolated melanin may find potential application for use in cosmetic and/or pharmaceutical industries. Significance and Impact of the Study: This investigation reports a marine Pseudomonas stutzeri strain HMGM‐7 [MTCC 11712] that produces significant quantities of melanin (6·7 g l−1) in sea‐water medium without the supplementation of L‐tyrosine. The confirmation of the produced melanin was carried out by various chemical and physical characterization studies. The isolated melanin may find potential application for use in cosmetic and/or pharmaceutical industries.