Effect of Temperature and Carbon Source on the Expression of $\beta$-Galactosidase Gene of Lactococcus lactis ssp. lactis ATCC 7962

• Published in: Journal of microbiology and biotechnology Vol. 9; no. 2; pp. 201 - 205
• Main Authors: Kim, Tea-Youn, Lee, Jung-Min, Chang, Hae-Choon, Chung, Dae-Kyun, Lee, Jong-Hoon, Kim, Jeong-Hwan, Lee, Hyong-Joo
• Format: Journal Article
• Language: Korean
• Published: 1999
• Subjects: beta$-galactosidase; catabolite repression; growth temperature; Lactococcus lactis ssp; lactis ATCC 7962; ccpA
• ISSN: 1017-7825; 1738-8872

The effects of growth temperature and a carbon source on the expression of $\beta$-galactosidase gene of Lactococcus lactis ssp. lactis ATCC 7962 (L. lactis 7962) were investigated. At $25^{\circ}C$, L. lactis 7962 had a higher $\beta$-galactosidase activity than cells grown at $30^{\circ}C$ or $37^{\circ}C$, although cells grew most quickly at $37^{\circ}C$ The highest $\beta$-galactosidase activity was observed in cells grown in M17 with lactose (l %) followed by cells grown in a galactose (1 %) medium. L. lactis 7962 exhibited the minimum $\beta$-galactosidase activity in glucose media, indicating catabolite repression. When the cellular levels of $\beta$-galactosidase mRNA were examined using slot blot hybridization, no significant differences were observed between cells grown at $25^{\circ}C$ and cells at $30^{\circ}C$ or $37^{\circ}C$ in the same media. This suggests that the quantity of $\beta$-galactosidase mRNA may not be the reason for the higher $\beta$-galactosidase activities of L. lactis 7962 at $25^{\circ}C$ The level of ccpA (Catabolite Control Protein) transcript remained almost constant during the exponential growth phase irrespective of a carbon sourse.