• P-ISSN 0974-6846 E-ISSN 0974-5645

Indian Journal of Science and Technology


Indian Journal of Science and Technology

Year: 2023, Volume: 16, Issue: 47, Pages: 4481-4489

Original Article

Photocatalytic Dye Degradation Potential of Silver Nanocomposite from Exo-polysaccharide of Bacillus sp., An Associative Bacterium of Sargassum wightii

Received Date:13 July 2023, Accepted Date:10 November 2023, Published Date:20 December 2023


Objectives: Screening, production, and characterization of exopolysaccharides (EPSs) from Bacillus sp., an associative bacteria isolated from marine seaweed Sargassum. To synthesize and characterize silver nanocomposites using EPS isolated from Bacillus sp. and to evaluate their application in dye degradation. Methods: Seaweed-associated bacteria were isolated from Sargassum wightii by serial dilution and pour plate method. The colonies capable of producing exopolysaccharides on YMG agar plates were purified and identified up to the Genus level by Bergy’s Manual of Determinative Bacteriology. The EPS-mediated silver nanoparticles (EPS-AgNPs) obtained from partially purified EPS were characterized by chemical analysis, UV-visible spectroscopy, FT-IR, SEM, and Powder XRD and evaluated for photocatalytic dye degradation. Findings : A seaweed-associated bacterium, Bacillus sp. was isolated from Sargassum wightii, and the extracted EPS was confirmed by the presence of amide, hydroxyl, and carboxyl groups in FTIR. Further, Exopolysaccharide- silver nano-composite was prepared. The characterization studies show a specific absorbance peak at 217 nm in the UV-Vis spectrum and the presence of hydroxyl and carboxyl groups in FT-IR spectroscopy. This confirms that EPS is responsible for the reduction of silver-to-silver nanoparticles. The SEM analysis reveals the formation of AgNPs with sizes ranging from 80-100 nm in a spherical shape. Under sunlight irradiation, the photocatalytic dye degradation of organic dyes like Congo red and methylene blue was studied with the synthesized exopolysaccharide-mediated silver nanoparticle (EPS-AgNPs). The percentage of degradation efficiency was calculated as 97% for Congo red and 95.6% for Methylene blue after 48 hours of exposure time. Novelty : The novel idea of the study was the utilization of potential associative bacterial isolate from seaweed Sargassum wightii which is capable of producing an EPS for the synthesis of silver nanocomposite. A significant achievement of this study is that the EPS component from the new bacterial isolate was suitable for the synthesis of silver nanocomposite which helps in the gradual photocatalytic degradation of textile dyes by providing a longer half-life and better degradation efficiency.

Keywords: EPS, SEM, AgNPs, FTIR, Sargassum


  1. Vikrant K, Giri BS, Raza N, Roy K, Kim KHH, Rai BN, et al. Recent advancements in bioremediation of dye: Current status and challenges. Bioresource Technology. 2018;253:355–367. Available from: https://doi.org/10.1016/j.biortech.2018.01.029
  2. Othman Z, Sinopoli A, Mackey HR, Mahmoud KA. Efficient Photocatalytic Degradation of Organic Dyes by AgNPs/TiO2/Ti3C2Tx MXene Composites under UV and Solar Light. ACS Omega. 2021;6(49):33325–33338. Available from: https://doi.org/10.1021/acsomega.1c03189
  3. Sharma D, Kanchi S, Bisetty K. Biogenic synthesis of nanoparticles: A review. Arabian Journal of Chemistry. 2019;12(8):3576–3600. Available from: https://doi.org/10.1016/j.arabjc.2015.11.002
  4. Chandrakala V, Aruna V, Angajala G. Review on metal nanoparticles as nanocarriers: current challenges and perspectives in drug delivery systems. Emergent Materials. 2022;5(6):1593–1615. Available from: https://doi.org/10.1007/s42247-021-00335-x
  5. Osagie C, Othmani A, Ghosh S, Malloum A, Esfahani ZK, Ahmadi S. Dyes adsorption from aqueous media through the nanotechnology: A review. Journal of Materials Research and Technology. 2021;14:2195–2218. Available from: https://doi.org/10.1016/j.jmrt.2021.07.085
  6. Khan A, Roy A, Bhasin S, Emran TB, Khusro A, Eftekhari A, et al. Nanomaterials: An alternative source for biodegradation of toxic dyes. Food and Chemical Toxicology. 2022;164:112996. Available from: https://doi.org/10.1016/j.fct.2022.112996
  7. Arayes MA, Mabrouk MEM, Sabry SA, Abdella B. Exopolysaccharide production from Alkalibacillus sp. w3: statistical optimization and biological activity. Biologia. 2023;78(1):229–240. Available from: https://doi.org/10.1007/s11756-022-01233-1
  8. Banerjee A, Sarkar S, Govil T, González-Faune P, Cabrera-Barjas G, Bandopadhyay R, et al. Extremophilic Exopolysaccharides: Biotechnologies and Wastewater Remediation. Frontiers in Microbiology. 2021;12:1–17. Available from: https://doi.org/10.3389/fmicb.2021.721365
  9. Alnadhari S, Al-Enazi NM, Alshehrei F, Ameen F. A review on biogenic synthesis of metal nanoparticles using marine algae and its applications. Environmental Research. 2021;194:110672. Available from: https://doi.org/10.1016/j.envres.2020.110672
  10. Hamidi M, Okoro OV, Milan PB, Khalili MR, Samadian H, Nie L, et al. Fungal exopolysaccharides: Properties, sources, modifications, and biomedical applications. Carbohydrate Polymers. 2022;284:119152. Available from: https://doi.org/10.1016/j.carbpol.2022.119152
  11. Ghosh T, Singh R, Nesamma AA, Jutur PP. Chapter 3: Marine Polysaccharides: Properties and Applications. In: Inamuddin, Ahamed MI, Boddula R, Altalhi T., eds. Polysaccharides: Properties and Applications. (pp. 37-60) Wiley. 2021.
  12. Costa JAV, Lucas BF, Alvarenga AGP, Moreira JB, Morais MGd. Microalgae Polysaccharides: An Overview of Production, Characterization, and Potential Applications. Polysaccharides. 2021;2(4):759–772. Available from: https://doi.org/10.3390/polysaccharides2040046
  13. Cirri E, Pohnert G. Algae−bacteria interactions that balance the planktonic microbiome. New Phytologist. 2019;223(1):100–106. Available from: https://doi.org/10.1111/nph.15765
  14. Hervé V, Lambourdière J, René-Trouillefou M, Devault DA, Lopez PJ. Sargassum Differentially Shapes the Microbiota Composition and Diversity at Coastal Tide Sites and Inland Storage Sites on Caribbean Islands. Frontiers in Microbiology. 2021;12:1–14. Available from: https://doi.org/10.3389/fmicb.2021.701155
  15. Sun X, Xue Z, Chen C, Fan S, Fu H, Wang P. Diversity of culturable alginate lyase-excreting bacteria associated with Sargassum. Acta Oceanologica Sinica. 2023;42(6):70–77. Available from: https://doi.org/10.1007/s13131-022-2095-0
  16. Huang-Lin E, Sánchez-León E, Amils R, Abrusci C. Potential Applications of an Exopolysaccharide Produced by Bacillus xiamenensis RT6 Isolated from an Acidic Environment. Polymers. 2022;14(18):1–21. Available from: https://doi.org/10.3390/polym14183918
  17. Minimol VA, Kishore P, Nadella RK, Sreelakshmi KR, Greeshma SS, Prasad MM, et al. Isolation and Characterization of Exopolysaccharide producing Bacillus cereus from Brown Seaweed- Sargassum wightii. International Journal of Current Microbiology and Applied Sciences. 2019;8(09):1302–1311. Available from: https://doi.org/10.20546/ijcmas.2019.809.149
  18. Hu X, Li F, Zhang X, Pan Y, Lu J, Li Y, et al. The structure, characterization and dual-activity of exopolysaccharide produced by Bacillus enclensis AP-4 from deep-sea sediments. Frontiers in Marine Science. 2022;9:1–16. Available from: https://doi.org/10.3389/fmars.2022.976543
  19. Singh RP, Shukla MK, Mishra A, Kumari P, Reddy CRK, Jha B. Isolation and characterization of exopolysaccharides from seaweed associated bacteria Bacillus licheniformis. Carbohydrate Polymers. 2011;84(3):1019–1026. Available from: https://doi.org/10.1016/j.carbpol.2010.12.061
  20. Jaast S, Grewal A. Green synthesis of silver nanoparticles, characterization and evaluation of their photocatalytic dye degradation activity. Current Research in Green and Sustainable Chemistry. 2021;4:1–6. Available from: https://doi.org/10.1016/j.crgsc.2021.100195
  21. Liaqat N, Jahan N, Khalil-Ur-Rahman, Anwar T, Qureshi H. Green synthesized silver nanoparticles: Optimization, characterization, antimicrobial activity, and cytotoxicity study by hemolysis assay. Frontiers in Chemistry. 2022;10:1–13. Available from: https://doi.org/10.3389/fchem.2022.952006
  22. Anil A, Sanjeev KG, Kamarudheen N, Sebastian PM, Rao KVB. EPS-mediated biosynthesis of nanoparticles by Bacillus stratosphericus A07, their characterization and potential application in azo dye degradation. Archives of Microbiology. 2023;205(2). Available from: https://doi.org/10.1007/s00203-023-03415-0
  23. Banerjee A, Sarkar S, Govil T, González-Faune P, Cabrera-Barjas G, Bandopadhyay R, et al. Extremophilic Exopolysaccharides: Biotechnologies and Wastewater Remediation. Frontiers in Microbiology. 2021;12:1–17. Available from: https://doi.org/10.3389/fmicb.2021.721365
  24. Rehman KU, Khan AU, Tahir K, Nazir S, Albalawi K, Hassan HMA, et al. Facile synthesis of copper oxide nanoparticles (CuONPs) using green method to promote photocatalytic and biocidal applications. Journal of Molecular Liquids. 2022;360:119453. Available from: https://doi.org/10.1016/j.molliq.2022.119453
  25. Dhaka A, Raj S, Githala CK, Mali SC, Trivedi R. Balanites aegyptiaca leaf extract-mediated synthesis of silver nanoparticles and their catalytic dye degradation and antifungal efficacy. Frontiers in Bioengineering and Biotechnology. 2022;10:1–14. Available from: https://doi.org/10.3389/fbioe.2022.977101


© 2023 Leela et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Published By Indian Society for Education and Environment (iSee)


Subscribe now for latest articles and news.