Silver Clusters Inhibit the Biofilm Formed by Bacillus Thuringiensis

Undergraduate #4
Discipline: Biological Sciences
Subcategory: Biochemistry (not Cell and Molecular Biology and Genetics)

Christa Corley - Tougaloo College
Co-Author(s): Keith Cobb, Jr., Elrica Brown, Bianca Garner, and Bidisha Sengupta

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Biofilms are catenation of bacteria on a surface, which are caged by the extracellularly secreted proteins, carbohydrates, and/or DNA. The phenotypes of these multicellular aggregates are distinct from those of planktonic cells. The biofilm formation is resistant to anti-microbial agents, which give rise to chronic bacterial infections and death in human beings. The present study is designed to explore the effect of silver nanolcusters on the biofilm formation by the bacteria Bacillus Thuringiensis. The silver clusters was made on the single stranded DNA oligonucleotide CCCACCCACCCTCCCA without and with a 5’ aptamer attached, in distilled water using AgNO3 and NaBH4 as the reducing agent. UV/Vis absorption and fluorescence emission studies characterized the absorption and emission properties. Bacterial growth and biofilm (using crystal violet stain) assay were performed in 96 well plate at 600 nm and 540 nm, respectively. Gram staining confirmed the purity of the samples. Transmission electron microscopy was performed on each sample. Silver nanoparticles formed on the cell membranes of the bacterial samples grown in presence of AgNO3, but no biofilm was observed in samples treated with Ag+ or silver nanoclusters. These nanoclusters are thought to be used as a mode of transportation silver particles. The present study proved the efficiency of silver as a potent anti-microbial agent and opens a new door to the future perspectives for its possible usage in therapeutics. Further studies are underway.

Funder Acknowledgement(s): NSF-ESPCoR

Faculty Advisor: Bidisha Sengupta,