PC scores plots generated using the 36 core K. pneumoniae-associated volatile compounds. The core compounds result in separation between K. pneumoniae cultures (red circles, n = 108) and uninoculated media controls (blue triangles, n = 20) (2a, left), and also reveal sub-structure within the K. pneumoniae culture samples as a function of growth media (2b, right). BHI: red squares, LB: green circles, MHB: pink diamonds, TSB: orange triangles, uninoculated media: blue triangles. (PC 1: 60 %, PC 2: 7 %). A three-dimensional scores plot is presented in Supplementary Figure S3.