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
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: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:Gene expression in Lactococcus lactis MG1363 was compared to that of L. lactis MG1363 â??guaA in rich GM17 medium. One condition design comparison of two strains
Project description:pBL1 is a Lactococcus lactis theta-replicating 10.9-kbp plasmid that encodes the synthetic machinery of the bacteriocin Lcn972. In this work, the transcriptomes of exponentially growing L. lactis with and without pBL1 were compared. A discrete response was observed with a total of ten genes showing significantly changed expression. Up-regulation of the lactococcal oligopeptide uptake system (opp) was observed, likely linked to a higher nitrogen demand required for Lcn972 biosynthesis. Striking, celB coding for the membrane porter IIC of the cellobiose-PTS and the upstream gene llmg0186 were down-regulated. Growth profiles for L. lactis strains MG1363, MG1363/pBL1 and MG1363ΔcelB grown in CDM-cellobiose confirmed slower growth of pBL1 and ΔcelB while no differences were scored on glucose. The presence of pBL1 shifted the fermentation products towards a mixed acid profile and promoted substantial changes in intracellular pool sizes for glycolytic intermediates in cellobiose-growing cells as determined by HPLC and NMR. Overall, these data support the genetic evidence of a constriction in cellobiose uptake. Notably, several cell wall precursors accumulated, while other UDP-activated sugars pools were lower, which could reflect rerouting of precursors towards the production of structural or storage polysaccharides. Moreover, slow cellobiose-growing cells and those lacking celB were more tolerant to Lcn972 than cellobiose adapted cells. Thus, down-regulation of celB could help to build-up a response against the antimicrobial activity of Lcn972 enhancing self-immunity of the producer cells. The transcriptomes of Lactococcus lactis MG1614 with and without the bacteriocinogenic plasmid pBL1, grown under laboratory conditions, were compared using three biological replicates.
Project description:Proteomics comparison of wild type Lactococcus lactis MG1363 with a mutant strain that has a point mutation in the global carbon catabolite repression regulator (CcpA) grown under glucose-limited chemostat conditions at D = 0.5 /h.
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