Evaluation of a chromogenic medium supplemented with glucose for detecting Enterobacter sakazakii

• Published in: Journal of microbiology and biotechnology Vol. 18; no. 3; pp. 579 - 584
• Main Authors: Song, K.Y. (JIFSAN, University of Maryland, Maryland, U.S.A.), Hyeon, J.Y. (Konkuk University, Seoul, Republic of Korea), Shin, H.C. (Konkuk University, Seoul, Republic of Korea), Park, C.K. (Konkuk University, Seoul, Republic of Korea), Choi, I.S. (Konkuk University, Seoul, Republic of Korea), Seo, K.H. (Konkuk University, Seoul, Republic of Korea), E-mail: bracstu3@konkuk.ac.kr
• Format: Journal Article
• Language: English
• Published: Seoul Korean Society for Applied Microbiology 01.03.2008
• Subjects: alpha-Glucosidases - metabolism; Bacteriological Techniques - methods; Biological and medical sciences; Biotechnology; chromogenic agar; Chromogenic Compounds - metabolism; Cronobacter sakazakii - cytology; Cronobacter sakazakii - isolation & purification; Cronobacter sakazakii - metabolism; Culture Media - chemistry; Enterobacter sakazakii; Escherichia - cytology; Escherichia - metabolism; Escherichia vulneris; Fundamental and applied biological sciences. Psychology; GLUCOSA; GLUCOSE; Glucose - metabolism; Escherichia; Enterobacter; Escherichia vulneris; Enterobacter sakazakii; Bacteria; Glucose; Chromogenic agar; Enterobacteriaceae
• ISSN: 1017-7825

A commercial chromogenic agar medium (DFI) was supplemented with glucose (mDFI) to enhance the specificity of Enterobacter sakazakii (E. sakazakii) detection. Escherichia vulneris (E. vulneris), a putative false-positive strain on the DFI medium, produces α-glucosidase. The enzyme α-glucosidase hydrolyzes a substrate, 5-bromo-4-chloro-3-indolyl-α,D-glucopyranoside (XαGlc), producing green colonies. E. sakazakii strains produced green colonies on both DFI and mDFI agar, whereas E. vulneris produced green colonies on DFI agar but small white colonies on mDFI agar. E. sakazakii and E. vulneris were also readily differentiated by colony color when the mixed culture of the two strains was plated on mDFI agar and incubated for 24 h at 37℃. The results indicate that the selectivity of the commercial chromogenic agar medium could be improved by a simple supplementation with glucose.