Abstract
ES Colimark agar contains two chromagenic substrates, 5-bromo-6-chloro-3-indolyl-β-D-galactopyranoside (Magenta-GAL) and 5-bromo-4-chloro-3-indolyl-β-D-glucuronide (X-GLUC).Various bacteria were tested for growth and colony color with ES Colimark agar. Also, for enumerating coliforms from viable bacteria, ES Colimark agar and Desoxycholate agar were compared in 413 food samples. Magenta colonies and dark blue to violet colonies that grew on ES Colimark agar were identified. The results of examination are as follows. 1) All gram negative bacteria (45 strains) that included coliforms grew on ES Colimark agar and appeared clearly in colorful colonies. 2) Coliforms were detected from 198 (47.9%) of 413 food samples by ES Colimark agar, significantly more than by Desoxycholate agar 48 (11.6%). 3) Bacteria of 150 magenta colonies that grew on ES Colimark agar and did not grow on Desoxycolate agar were identified as 12 species which included P. agglomerans (43 strains) and E. cloacae (27 strains). 4) Eighty-eight dark blue to violet colonies on ES Colimark agar were identified as E. coli (87 strains, 98.9%) and only 1 strain was not identified. These results confirmed that ES Colimark agar could detect coliforms more broadly than the conventional method. Therefore, ES Colimark agar was considered useful for food safety science.
