ABSTRACT
For practical purposes, the growth medium should be defined as “rich”, or more accurately, the medium that supports the most rapid growth under optimal salt concentrations. To return to such techniques, yeast extract seems to serve well for the growth of most halophilic archaebacteria, but all constituents of complex media do not. Both the optimal and the maximal salt concentrations for growth of Deleya halophila are shifted up by increasing temperature in the range of 22 to 42 C. Richer nutritional conditions can also widen the salt range of growth. Though halophilic archaebacteria are usually grown at 37 C, their optimal temperature for growth is probably higher; values up to 50 C for this have been reported. Interestingly, growth at, or even exposure to, higher salt concentrations may be accompanied by an adaptation in active transport systems of several bacterial species, so that cells can take in solutes at higher external salt concentrations than before.
