Bacterial response to permafrost derived organic matter (tDOM) input in an Arctic fjord (Kongsfjord)

We tested experimentally the effects of tDOM on the bacterial community composition and net-growth by extracting DOM from the active layer of permafrost soil and adding the aged tDOM concentrate to a fjord microbial community (Kongsfjorden, NW Svalbard). The responses in terms of bacterial community composition and cell numbers were monitored in the treatment and control bottles at eight different time points spanning over nine days in total (start [0d], 0.5d, 1d, 2d, 3d, 4d, 5d, 9d), by harvesting one of the eight replicates, each from the tDOM treatment and control bottles, at every sampling occasion. Samples for RNA extraction were collected by filtering the water onto 0.22 µm pore size Millipore® Sterivex filters.