Abstract:
Marine microorganisms are a potential source of secondary metabolites that include
biopigments produced in response to harsh environmental conditions as a defence
mechanism. The current study aimed to extract, isolate and characterise marine
biopigments in addition to assessing their potential Ultraviolet (UV) protective and
antimicrobial properties. Pigment producing bacterial strains were isolated from marine
samples obtained from various Western coastal regions of Sri Lanka by following
standard microbial isolation protocols. The isolates were grown on Marine Nutrient
Agar and the most prominent pigmented bacterial strain isolated from Negombo was
chosen for extraction and characterization. The strain was characterised via standard
morphological and biochemical testing for tentative identification. The pigment was
extracted via ultrasonication and characterised by Thin Layer Chromatography using
methanol as a solvent. The Ultraviolet protective and antimicrobial properties were
determined through Sun Protection factor (SPF) assay and Kirby-Bauer Well-Diffusion
method respectively. The findings indicate that the isolate protection was a yellow
pigmented bacterial strain tentatively identified to be belonging to the Micrococcus
genus. The extracted pigment was speculated to be a member of the carotenoid group of
pigments. Using the Mansur method, the pigment was found to have a Sun Protection
factor of 24.80 which falls within the range of commercially available sunscreens.
Moreover, the pigment exhibited antibacterial activity against Gram positive bacteria:
Staphylococcus aureus, Zone of Inhibition (ZOI) =15 mm, Bacillus cereus, ZOI =25
mm and Gram-negative bacteria Escherichia coli, ZOI=18 mm while antifungal activity
was also evident against Candida albicans (ZOI=21 mm) These findings suggest that
the pigment ventures promising applications in sunscreen formulations as well as a
potential adjunct in antimicrobial therapy. Further characterization of pigment could
determine its organic nature and better its understanding for application in both the
cosmetic and medical industry.
