Project description:Lactococcus lactis is one of the most important lactic acid bacterium used in the dairy industry. Activation of natural DNA transformation in this species would greatly improve the selection of novel strains with desired industrial traits. Here, we investigate the activation of natural transformation in L. lactis ssp. cremoris KW2, a strain of plant origin whose genome encodes the master competence regulator ComX and the complete set of essential late gene products required for natural transformation under its potential control. In absence of any information on the competence signaling system in this species, activation of natural DNA transformation by the constitutive production of ComX was attempted. Using a reporter strain of late competence phase activation and transcriptomic analyses, we show that all key genes for natural transformation can be induced in strain KW2. Then, we demonstrate that natural DNA transformation is functional in this strain and that this process requires the DNA uptake machinery dedicated to competence. Various chromosomal modifications such as point mutations or gene deletion/insertion could be quickly and efficiently achieved. These results are the first to report the functionality of natural DNA transformation in L. lactis and pave the way for the identification of molecular mechanisms activating competence development in this species.
Project description:Temperature is an important factor affecting biological organisms. We characterize a Lactococcus lactis (L. lactis) ssp. cremoris MG1363 mutant (CS3527) capable of growing better at a higher temperature than its parent. The transcriptomic analysis also revealed widespread down-regulation of genes encoding membrane transport proteins in the wild-type at 38°C. A fatty acid composition analysis revealed that the mutant has substantially more straight chained saturated and less cyclopropane fatty acids at 30°C and 38°C compared with the wild-type.
Project description:Temperature is an important factor affecting biological organisms. We characterize a Lactococcus lactis (L. lactis) ssp. cremoris MG1363 mutant (CS3527) capable of growing better at a higher temperature than its parent. The transcriptomic analysis also revealed widespread down-regulation of genes encoding membrane transport proteins in the wild-type at 38°C. A fatty acid composition analysis revealed that the mutant has substantially more straight chained saturated and less cyclopropane fatty acids at 30°C and 38°C compared with the wild-type. MG1363 versus CS3527 at two different growth temperatures
