RNA-SEQ Reveals Changes in the Staphylococcus aureus Transcriptome Following Blue Light Illumination

Drum, Bayless
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Staphylococcus aureus infections are becoming a more serious human health concern as antibiotic resistance among S. aureus strains increases. As a result, alternatives to antibiotic treatments are being explored, including photodynamic therapies. It has been shown that blue light exposure will inhibit the growth of both Gram-positive and Gram-negative bacteria, including S. aureus growing in culture. However, the mechanism of this inhibition is not well characterized. In an effort to better understand the mechanism of blue light inhibition, a whole transcriptome analysis of S. aureus isolate BUSA2288 was performed using RNA-seq to analyze the response to blue light exposure. RNA was extracted from S. aureus cultures illuminated with blue light, and control cultures grown in the dark. Transcriptomic comparisons using a cutoff of 5 fold identified a total of 28 down-regulated genes and 6 up-regulated genes in the samples that were exposed to blue light. The differentially regulated genes fall into 8 functional categories with 4 genes of unknown function. These results indicate that blue light does have an effect on the transcriptome of S. aureus. Pathways involving reactive oxygen intermediates generated in the broth and excitation and damage to membrane proteins are proposed to explain the killing effect of blue light on S. aureus.

Antibiotic resistance., RNA-seq., Staphylococcus aureus., Phototherapy., Reactive oxygen intermediates., MRSA.