Comparative functional profile of microbial communities on Deception Island volcano
Functional profiles of metagenomes were compared using a multivariate method and hypothesis test, and significant variations in all functional levels were observed between the 98 oC fumarole, <80 oC fumaroles and glaciers. Clear differences between these three distinct sample groups were observed through both the SEED Level 1 profile (Figure 3a) and SEED functional level through PCA ordination (Figure 3b). Further, a distinct pattern between samples from the highest temperature was observed. The prevalent core of functions among Deception samples were “clustering-based subsystems”, “carbohydrates”, “amino acids and derivatives”, “protein metabolism”, “RNA metabolism”, “DNA metabolism” and “cofactors, vitamins, prosthetic groups and pigments”. Significant differences between sample groups and functions from level 1 of SEED, calculated using Fisher’s exact two-sided test and the Newcombe-Wilson method, showed the highest abundance of genes belonging to the categories “DNA metabolism” (p = 0.046), “protein metabolism” (p = 0.049), and “phages, prophages, transposable elements and plasmids” (p = 3.97e-3) in the 98 oC fumarole in comparison with other fumaroles and glaciers. The categories “nitrogen metabolism” (p = 1.07e-4), “photosynthesis” (p = 5.07e-3), “sulfur metabolism” (p = 0.015), and “metabolism of aromatic compounds” (p = 0.036) exhibited the highest significant values in <80 oC fumaroles when compared to the 98oC fumarole, and “motility and chemotaxis” (p= 2.71e-8), “RNA metabolism” (p = 0.01), and “protein metabolism” (p = 0.023) when compared to glaciers. In contrast, observations for glaciers showed more genes associated with “carbohydrates” and “virulence, disease and defense” categories in comparison with the 98 oC fumarole (p = 0.049 and p = 0.036, respectively) and <80oC fumaroles (p = 1.68e-6 and p = 0.012, respectively) (Figure 3c).