• Journal of Microbiology and Biotechnology
• /
• 제18권3호
• /
• pp.579-584
• /
• 2008

A commercial chromogenic agar medium (DFI) was supplemented with glucose (mDFI) to enhance the specificity of Enterobacter sakazakii (E. sakazakit) detection. Escherichia vulneris (E. vulneris), a putative false-positive strain on the DFI medium, produces ${\alpha}$-glucosidase. The enzyme ${\alpha}$-glucosidase hydrolyzes a substrate, 5-bromo-4-chloro-3-indolyl-${\alpha}$, D-glucopyranoside $(X{\alpha}Glc)$, 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 $37^{\circ}C$. The results indicate that the selectivity of the commercial chromogenic agar medium could be improved by a simple supplementation with glucose.

• Food Science and Biotechnology
• /
• 제14권6호
• /
• pp.875-877
• /
• 2005

Presence of Enterobacter sakazakii, occasional pathogen of powdered infant formula causing rare, but life-threatening diseases such as neonatal meningitis, bacteremia, necrotizing enterocolitis, and necrotizing meningoencephalitis after ingestion was examined in 45 powdered infant formula products manufactured in Korea using chromogenic Druggan-Forsythe-Iversen (DFI) medium, and isolates were identified with API 20E. Ent. sakazakii was isolated from three products. Ent. sakazakii isolates were genotyped by RAPD-PCR using two random primers, and their banding patterns were compared.

• 한국수산과학회지
• /
• 제44권3호
• /
• pp.251-258
• /
• 2011

To investigate whether the rearing environmental factors (size heterogeneity, rearing density, and feeding frequency) affect the growth and cannibalism of fry in cultured puffer Takifugu obscurus, we conducted three experiments. To examine size effects, we used small (total length [TL] $26.0{\pm}0.5\;mm$, body weight [BW] $0.18{\pm}0.01\;g$), medium (TL $23.1{\pm}0.1\;mm$, BW $0.28{\pm}0.01\;g$), large (TL $26.0{\pm}0.2\;mm$, BW $0.48{\pm}0.01\;g$) and small-large size combination groups. For density, we used size-matched puffers (TL $25.0{\pm}0.5\;mm$, BW $0.53{\pm}0.03\;g$) and five density were examined ranging from 1.43 to 7.14 individuals/L. For the feeding frequency, we also used size-matched fry and feeding frequencies of three times/2 days, one time/day, two times/day, three times/day. We ran each experiment in triplicate and investigated the survival rate, daily food intake (DFI), feed efficiency (FE), and daily growth rate (DGR). The growth of the puffers increased with increasing size, density, and feeding frequency, while cannibalism increased with a greater size gap, density and lower feeding frequency. Therefore, we concluded that size, rearing density, and feeding frequency are major factors influencing growth and cannibalism of the puffer, T. obscurus.