Fig 4. A 2-D plot of the first two principal component (PC) scores and loadings calculated from the filtered dataset of the metabolites in permafrost microbial cells at the three different sample locations and thawed from -3 ^oC to 6 ^oC.

Figures a and b are the PC scores and loading from the ESI+ mode and figures c and d are the PC scores and loadings from the ESI- mode, respectively. Variables in the top or lower 10% of the PCA loadings are the significant metabolites and these significant metabolites are in brackets in the loading plots.