Project description:Compare the physiological state between static, aerobic, and respiratory growth of Lactococcus lactis subsp. lactis CHCC2862 using whole genome transcriptomes. NOTE: the biological replicate array GSM243206 is dye-swapped relative to GSM202337 (unlike the two other biological replicate arrays GSM243203 and GSM24205). Keywords: Physiological response to aerobic and respiratory growth relative to static.
Project description:This SuperSeries is composed of the following subset Series: GSE23987: Transcriptomic profiles of six strains of Lactococcus lactis in ultrafiltration-cheese model GSE23990: Comparative genome hybridization profiles of six strains of Lactococcus lactis Refer to individual Series
Project description:The stringent response was defined in Lactococcus lactis through transcript profiling after the addition of a chemical inductor, the norvaline. Gene expression was measured in the exponential growth phase (reference sample) and at 1.6 h after norvaline addition. Four hundred and sixty one differentially expressed genes were identified and constituted the stringent response regulon. Keywords: stress response, time course Stringent response was imposed through norvaline addition during the growth of Lactococcus lactis IL1403 under controlled conditions (30 °C, pH 6.6, nitrogen atmosphere). Cell samples were harvested in exponential phase and 1.6 h after norvaline addition. Total RNA was extracted from these samples and radiolabelled cDNA were prepared and hybridized on nylon arrays. 2053 amplicons specific of Lactococcus lactis IL1403 genes were spotted twice on the array. The 2 time-points were analyzed simultaneously and 3 independent repetitions were performed.
Project description:The intra sub-species diversity of six strains of Lactococcus lactis subsp. lactis was investigated at the genomic level and in terms of phenotypic and transcriptomic profiles in UF-cheese model. Six strains were isolated from various sources, but all are exhibiting a dairy phenotype. Our results showed that, the six strains exhibited small phenotypic differences since similar behaviour in terms of growth was obtained during cheese ripening while only different acidification capability was detected. Even if all strains displayed high genomic similarities, sharing a high core genome of almost two thousands genes, the expression of this core genome directly in the cheese matrix revealed major strain-specific differences. This strains with the same dairy origin.
Project description:Lactococcus lactis NZ9000 and its parent MG1363 are the most commonly used lactic acid bacteria for expression and physiological studies. We noted unexpected but significant differences in the growth behaviors of both strains. We sequenced the entire genomes of the original NZ9000 and MG1363 strains using an ultradeep sequencing strategy. The analysis of the L. lactis NZ9000 genome yielded 79 differences, mostly point mutations, with the annotated genome sequence of L. lactis MG1363. Resequencing of the MG1363 strain revealed that 73 out of the 79 differences were due to errors in the published sequence. Comparative transcriptomic studies revealed several differences in the regulation of genes involved in sugar fermentation, which can be explained by two specific mutations in a region of the ptcC promoter with a key role in the regulation of cellobiose and glucose uptake.
