Chemostat adaptation of Escherichia coli B/r/1 to low water activity

Chemostat cultures of Escherichia coli B/r/1 under conditions of glucose limitation in a salts medium at high water activity ( a w of 0.999) and at an a w of 0.987, controlled by NaCl, have been compared. The system was run at dilution rates above 0.035 h ‐1 . The results suggested that the organism adapted to the lower a w of the medium as no significant change was observed in the energy requirement for maintenance, although the maximum molar growth yield for glucose decreased by 23.2%. Such cultures showed also a shorter lag and a higher growth rate in batch at an a w of 0.987, as compared with cultures initiated with an unadapted ( a w of 0.999) inoculum.