Comparative phenotype analysis of two or more microorganisms using a plurality of substrates within a multiwell testing device

A method for comparing at least two cell preparations, comprising the steps of:

• a) providing a first testing device and a duplicate second testing device, each comprising a plurality of testing wells and at least two test substrates selected from the group consisting of nitrogen sources, phosphorus sources, sulfur sources, and auxotrophic supplements, and wherein each well contains at least one of said test substrates;
• b) preparing a first suspension comprising a first cell preparation, in an aqueous solution, and a second suspension comprising a second cell preparation in an aqueous solution;
• c) introducing said first suspension into said wells of said first testing device, and said second suspension into said wells of said second testing device;
• d) detecting the response of said first and second cell preparations to said at least two test substrates, wherein said response is detected using a single chromogenic compound;
• and
• e) comparing the response of said first and second cell preparations.