Antibacterial mode of action of alpha-mangostin on Staphylococcus epidermidis

Alpha-mangostin (α-MG) is a natural xanthone reported to exhibit rapid bactericidal activity against Gram-positive bacteria, and may therefore have potential clinical application in healthcare sectors. This study sought to identify the antibacterial mode of action of α-MG against Staphylococcus epidermidis RP62A through RNA-sequencing technology. Overnight cultures of S. epidermidis were diluted 1:100 in LB and were grown to mid-log at 37 °C. Bacterial cells were treated with 0.7 MIC (0.875 µg/ml) of α-MG or 0.1 % methanol (solvent control) for 10 min. After incubation, bacterial total RNA was isolated. Samples were prepared in triplicates. The ribosomal RNA was depleted using Ribo-Zero rRNA Removal kit for Gram-positive bacteria. Sequencing library was prepared using the drop-seq protocol (Macosko et al., 2015) with specially designed random hexamer-based capture oligos with known barcodes. Paired-end sequencing was performed on NextSeq500 sequencer (Illumina) in FuGU (Helsinki, Finland).