Microbial activity and viability in ice-VI. Upon ice nucleation (0 hours, 1400 MPa), organic fluid veins (v) filled with bacteria (Shewanella MR1 on the left, E. coli stained with methylene blue on the right) appear. After ~1 hour, textural changes in the ice occur, defined by the formation of organic-rich inclusions (i) containing motile bacteria [Web movie 2 (12)]. Viable (methylene blue in solution remains colorless indicating respiration) and countable bacteria (b) were observed upon subsequent lowering of pressure [Web movie 3 (12)].

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