The use of gel-stabilized gradient plates to map the responses of microorganisms to three or four environmental factors varied simultaneously

The Szybalski wedge plate technique has been used to map the responses of bacteria to up to 4 simultaneously varying environmental factors. 2-dimensional NaCl-pH gradient plates were used throughout. Sets of the latter were incubated at a range of temperatures to provide a third dimension. A fourth variable, nitrate concentration, was investigated by incorporating it homogeneously in sets of NaCl-pH gradient plates.