Background: With the recent advances of nanotechnological interventions, nanoparticles
have found immense importance in various sectors of water, energy, health, agriculture and environment.
Concurrently, there has been an increasing concern about their toxicity on living systems. The
bactericidal role of silver nanoparicle is well established. The present work explores the interaction of
silver nanoparticles with halophilic bacteria Bacillus sp. EMB9. Given that halophiles thrive under saline/
hypersaline habitats and retain their structural and functional integrity under such high salt conditions,
they present a new and interesting model system for understanding their interactions with metals
in nanoparticulate form.
Methods: Bacillus sp. EMB9 was incubated in the presence and absence of 1.0 mM silver nanoparticles and their growth
profile monitored. Their responses towards the nano-stress environment were further evaluated using a proteomic
Result: Despite initial nanotoxic effects, Bacillus sp. EMB9 was able to resist silver mediated nanotoxicity and grow with
a high specific growth rate. Proteomic analysis showed striking global changes in the intracellular bacterial proteome with
almost a 50% reduction in the number of expressed proteins in the cells grown in presence of silver nanoparticles. Out of a
total of 261 protein spots detected, 24 were newly expressed and expression of 132 spots was suppressed completely in
the nanoparticle treated cells.
Conclusion: The differential expression patterns are indicative of adaptive strategies being employed by the bacteria for
functioning of the cellular machinery amidst nano-stress. A comprehensive understanding of the response of halophilic
Bacillus sp. EMB9 to silver nanoparticles will provide significant insight into mechanistic interpretations of bacteriananoparticle