1 IIIrd Year MBBS Student, Sree Balaji Medical College and Hospital, Chrompet, Chennai, Tamil Nadu, India
2 Assistant Professor, Department of Physiology, Krishnanagar Institute of Medical Sciences, Krishnanagar, Nadia, West Bengal, India
3 Associate Professor, Department of Anatomy, Karpaga Vinayaga Institute of Medical Sciences, Chengalpattu, Tamil Nadu, India
4* Assistant Professor, Department of Physiology, Sree Balaji Medical College and Hospital, Chrompet, Chennai, Tamil Nadu, India (Corresponding Author)
5 Department of Physiology, Sree Balaji Medical College and Hospital, Chrompet, Chennai, Tamil Nadu, India
6 Centre for Laboratory Animal Technology and Research, Sathyabama Institute of Science and Technology, Chennai, Tamil Nadu, India
Background and Objectives
Tuberculosis remains a major global health burden, exacerbated by the emergence of multidrug-resistant and extensively drug-resistant strains of Mycobacterium tuberculosis. Marine microorganisms, particularly species of the genus Bacillus, are recognized sources of antimicrobial peptides with broad biological activity. This study aimed to isolate Bacillus species from marine sediments and evaluate their antibacterial and antimycobacterial potential with reference to tuberculosis.
Materials and Methods
Marine sediment samples were collected from five coastal locations along the East Coast Road, Chennai, India. Bacterial isolates were obtained by serial dilution and culture on nutrient agar, followed by morphological, cultural and biochemical characterization. Antimicrobial activity was screened using well diffusion, agar plug and direct spot assays against standard bacterial pathogens. Optimization of bioactive metabolite production was performed by varying pH, temperature, incubation period and nutrient sources. Bioactive compounds were extracted using organic solvents and partially purified by thin-layer chromatography. Antimycobacterial activity was assessed using the luciferase reporter phage assay.
Results
Forty-three bacterial isolates were obtained, with counts ranging from 1.2 × 10³ to 1.5 × 10⁵ CFU/g of soil. Gram-positive isolates accounted for 53.48%, while 37.2% of colonies were pigmented. Among 17 Bacillus isolates screened, 7 (40.17%) exhibited antibacterial activity. Isolate KP3 showed broad-spectrum antibacterial activity with inhibition zones of 24 mm against Bacillus subtilis, 21 mm against Acinetobacter baumannii, 20 mm against Staphylococcus aureus, 18 mm against Escherichia coli and 16 mm against Klebsiella pneumoniae and Pseudomonas aeruginosa. Ethyl acetate extraction yielded 180 mg of crude compound per litre and the active TLC fraction showed an Rf value of 0.7 with inhibition zones up to 28 mm. No isolate demonstrated antimycobacterial activity.
Conclusions
Marine-origin Bacillus isolate KP3 produces potent antibacterial compounds with broad-spectrum activity, supporting further investigation of marine Bacillus-derived peptides as antibacterial agents.
Keywords: Bacillus; antimicrobial peptides; marine bacteria; tuberculosis; antibacterial activity
Abbreviations: AMP, antimicrobial peptide; MDR, multidrug-resistant; XDR, extensively drug-resistant; CFU, colony-forming units; LRP, luciferase reporter phage
How to cite this article: Deborah P, Balakrishnan B, Ammal SA, Priyanka G, Devaki PR, Saravanan D. Identification and Characterization of Antimycobacterial Peptides from Marine Origin Bacillus Species with Relation to Tuberculosis. Int J Drug Deliv Technol. 2026;16(4): 275-283. DOI: 10.25258/ijddt.16.4.29
Source of support: Nil.
Conflict of interest: None