Synthesis of nano silver by a marine epibiotic bacterium Bacillus vallismortis and its potent ecofriendly antifouling properties

- Biogenic silver nanoparticles (AgNPs) were synthesized using Bacillus vallismortis.
- AgNPs were characterized by both spectroscopical and microscopical techniques.
- AgNPs were found to be smaller in size, fairly polydispersed and spherical in shape.
- Biosynthesized AgNPs exhibited promising antimicro- and antimicrofouling activities.

In the present study, biosynthesis of silver nanoparticles (AgNPs) by a newly isolated marine epibiotic bacterium Bacillus vallismortis and its potent antifouling (AF) activity was investigated. Biosynthesized AgNPs were primarily confirmed by change in colour from yellow to brown. UV-vis spectrum of the AgNPs showed surface plasmon resonance (SPR) peak at 426 nm. The AgNPs were further characterized using FT-IR spectroscopy, XRD, SEM and HRTEM analysis. The synthesized AgNPs were narrowly polydispersed and spherical in shape with an average particle size of 23 nm. Antibacterial activity inferred that the AgNPs effectively inhibited marine biofilm forming bacterial strains with minimal MIC and MBC values. Moreover, Confocal Laser Scanning Microscopic images evidenced good antibiofilm efficacy of the AgNPs. It had also strongly inhibited fouling microalgal growth at minimal nanomolar (nM) concentration in the range of 0.5-1 nM. Anticrustacean assay using Artemia franciscana larvae registered LC50 value of 11.59 nM. Further, EC50 < LC50 and 100% recovery of mussel Perna indica in toxicity assay propagated non-toxic nature of the AgNPs. Current study clearly explored the possibility of utilizing AgNPs biosynthesized by B. vallismortis in AF coatings to combat biofouling.

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