Figure 2
From: Is there a common water-activity limit for the three domains of life?
Growth curves for halophilic Bacteria and Archaea cultured in high-NaCl substrates and plotted in relation to water activity. (a) The bacterium Halorhodospira halochloris (strain and incubation temperature not specified) cultured in a defined medium supplemented with NaCl (calculated and replotted against water activity using data from Deole et al., 2013). (b) The bacterium Halorhodospira halophila (strain DSM 244T; incubation temperature not specified) cultured in a defined medium supplemented with NaCl (calculated and replotted against water activity using data from Deole et al., 2013). (c) The bacterium Halanaerobium lacusrosei (strain DSM 10165T) cultured in a complex medium supplemented with NaCl and incubated at 37 °C (calculated and replotted against water activity using data from Cayol et al., 1995). (d) The Aacterium Actinopolyspora halophila (strain ATCC 27976T) cultured in a complex medium supplemented with NaCl, after a 14-day incubation at 37 °C (calculated and replotted against water activity using data from Yoshida et al., 1991). (e) The Archaea ‘Haloarcula californiae’ (strain DSM 8905; black line) and ‘Haloarcula sinaiiensis’ (strain DSM 8928; orange line) cultured in a complex medium supplemented with NaCl and incubated at 37 °C (calculated and replotted against water activity using data from Javor et al., 1982). (f) The archaeon Halorhabdus utahensis (strain DSM 12940T) in a defined medium supplemented with NaCl and incubated at 30 °C (calculated and re-plotted against water activity using data from Wainø et al., 2000). For all media, water activity values were determined as described in the Materials and methods and at the same temperature as incubation was carried out for each set of media. Curves were extrapolated via regression analyses (dotted lines; for details see Supplementary Table S1) in order to determine the theoretical water activity minima for growth. Pink dashed lines indicate the previously accepted water activity limit for extremely halophilic Bacteria and Archaea (see Brown, 1990; Grant, 2004; Kminek et al., 2010).
