Title:Characterization and Antibacterial Activity of Melanin Pigment from
Marine Bacterium Actinoalloteichus cyanogriseus
Volume: 21
Issue: 5
Author(s): Muddukrishnaiah Kotakonda, Makesh Marappan*Bhaskar Biswas
Affiliation:
- Fish Culture Division, ICAR- Central Institute of Brackishwater Aquaculture, Chennai, 600028, India
Keywords:
Marine sediment bacteria, Actinoalloteichus cyanogriseus, melanin, UV, AU-RM-4, antibacterial activity.
Abstract:
Introduction: Marine microbes are known to produce novel bioactive compounds. In this
work, the bacterium Actinoalloteichus cyanogriseus, AU-RM-4, isolated from marine soil sediment, capable
of producing high amounts of black extracellular melanin pigment when grown on anaerobic actinomycetes
agar is reported. The maximum melanin production was approximately 2.5 mg/mL.
Methods: The melanin pigment was recovered using acid treatment and the characteristic melanin absorption
peaks at 253 nm and 291 nm were observed in the UV range. The antibacterial activity of the melanin
pigment against a range of clinically infectious bacteria was assayed in vitro by disc diffusion and serial
dilution methods.
Results: The A. cyanogriseus melanin showed antimicrobial activity against Staphylococcus aureus and
Klebsiella pneumoniae (MIC value -500 μg/mL). The effects of the AU-RM-4 melanin on the morphology
of pathogenic bacteria were observed under scanning (SEM) and transmission electron microscopy
(TEM). It is concluded that A. cyanogriseus isolate AU-RM-4 is a promising melanin-producing marine
bacterium, whose melanin pigment has antibacterial activity against certain pathogenic bacteria (S. aureus
and K. pneumoniae).
Conclusion: Melanin produced by A. cyanogriseus AU-RM-4 could have commercial potential in the
pharmaceutical and cosmetic industries for the production of pharmaceutical formulations, and also in the
food industries as a colouring and antibacterial agent.
