Abstract
A semi-micromethod is described for characterizing anaerobic bacteria by substrate utilization. Small volumes of individual substrates were placed in the wells of plastic microtiter trays. When heavy inocula and a colorimetric indicator were used, complete results were available after 30 h of incubation. Microtiter trays containing a range of substrates can be stored at -20 degrees C. The method is accurate, economical, and convenient for use in a hospital microbiology laboratory.