| Autor: |
Hornbæk, Tina, Jakobsen, Mogens, Dynesen, Jens, Nielsen, Allan |
| Předmět: |
|
| Zdroj: |
Archives of Microbiology; Dec2004, Vol. 182 Issue 6, p467-474, 8p |
| Abstrakt: |
For optimization of propagation conditions for an industrially usedBacillus licheniformis, this study examines the effect of transferring cells at the early-stationary growth phase (pH 5.3) to fresh growth medium at pH 5.0-8.0. Intracellular pH (pHi) was measured on a single-cell level, using fluorescence ratio imaging microscopy after staining with 5(6)-carboxyfluorescein diacetate succinimidyl ester. Transcription profiles were determined using a genome DNA microarray. The optimum extracellular pH (pHex) value for growth ofB. licheniformiswas found to be pH 7.0, resulting in the shortest lag phase, highest maximum specific growth rate and maximum biomass formation. An average pH gradient (?pH = pHi - pHex) of approx. 1.0 was found inB. licheniformis15 min after transfer to pHex 5.0-8.0. Up-regulation of genes involved in sucrose uptake at pH 7.0 could be related to the optimum growth observed. Transcription profiles indicated that the organism was experiencing phosphate starvation upon transfer to pH 7.0 and pH 8.0. Mechanisms involved in pHi regulation appeared to include changes in fatty acid synthesis to yield a more rigid cell membrane structure at low pHex values and conversion of pyruvate to acetoin instead of acetate for neutralization of low pHex values. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
Full text from SpringerLink