1*Research Scholar, Department of Biotechnology, Malankara Catholic College, Mariagiri, affiliated to Manonmaniam Sundaranar University, Abishekapatti, 627012, Tirunelveli, India
2Head and Associate Professor, Department of Biotechnology, Malankara Catholic College, Mariagiri, Kaliakkavilai, Kanyakumari District. Email: manjuaruljose@gmail.com
Corresponding Author: Briscilla C
Background: Marine ecosystems represent a valuable reservoir of metabolically diverse microorganisms with significant biotechnological potential. In the present study, a red pigment–producing bacterium was isolated from seawater samples collected from the Gulf of Mannar and evaluated for its antimicrobial and antioxidant properties.
Methods: Among isolates, strain KW-1 exhibited intense red pigmentation and was selected for detailed characterization through the morphological, biochemical, and 16S rRNA gene sequencing analysis (99% similarity; GenBank Acc. No. PQ008550) the isolates was identified the isolate as Bacillus licheniformis. Optimization studies revealed maximum pigment production in medium supplemented with 5% starch and 5% yeast extract. The methanolic pigment extract demonstrated selective antibacterial activity, with the highest inhibition observed against Escherichia coli (1.07 ± 0.05 cm) and Helicobacter pylori (1.27 ± 0.05 cm). Antioxidant potential was confirmed through DPPH and ABTS radical scavenging assays, showing concentration-dependent activity with IC₅₀ values of ~63 µg/mL (DPPH) and ~82.9 µg/mL (ABTS), indicating moderate to strong antioxidant capacity.
Results: TLC (Rf = 0.5), FTIR, and GC–MS analysis revealed the predominance of cyclic dipeptides (diketopiperazines), while LC–MS confirmed the presence of Pulcherriminic acid (m/z 257.150 [M+H]⁺), the precursor of the iron-chelating pigment pulcherrimin.
Conclusion: Collectively, these findings establish B. licheniformis KW-1 as a promising marine-derived source of bioactive pigments with antimicrobial and antioxidant potential suitable for biotechnological applications.
Keywords: Bacillus licheniformis, pulcherrimin, Pulcherriminic acid, antimicrobial activity, antioxidant activity, cyclic dipeptides, marine bacteria
How to cite this article: Briscilla C, Manjusha WA. Isolation, Characterization, and Bioactive Potential of a Red Pigment Producing Bacillus licheniformis Strain from the Gulf of Mannar. Int J Drug Deliv Technol. 2026;16(13s): 1023-1042. DOI: 10.25258/ijddt.16.13s.113.
Source of support: Nil.
Conflict of interest: None