Project description:Comparison of overall tRNA level in Lactococcus lactis affected by the growth rate and as a response to the overexpression of the membrane protein OpuA.
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:we report the identification and sequences of the tRNAome of industrially relevant microorganism Lactococcus lactis Three Next Generation sequencing runs annotated as S1, S2 and S3 were performed. Cells were harvested at exponential phase and tRNA was isolated. S1 and S2 were spiked with Phe-tRNAGAA from yeast and Lys-tRNAUUU from E. coli prior to cell lysis. S3 was spiked with Phe-tRNAGAA from yeast and Lys-tRNAUUU from E. coli before the library preparation to estimate the possible loss of tRNA in the extraction process.
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: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. Static stationary cultures of CHCC2862 (Chr. Hansen Culture Collection, Hørsholm, Denmark) were inoculated into fresh pre-heated medium at the relevant conditions. OD600 was followed over time. At OD 1.0 samples were harvested for RNA isolation.
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 development of transcriptomic tools has allowed exhaustive description of stress responses. These responses always superimpose a general response associated to growth rate decrease and a specific one corresponding to the stress. The exclusive growth rate response can be achieved through chemostat cultivation, enabling all parameters to remain constant except the growth rate. We analysed metabolic and transcriptomic responses of Lactococcus lactis in continuous cultures at different growth rates ranging from 0.09 to 0.47 h-1. Growth rate was conditioned by isoleucine supply. Although the metabolism was constant and homolactic, a widespread transcriptomic response involving 30 % of the genome was observed. The expression of genes encoding physiological functions associated with biogenesis increased with growth rate (transcription, translation, fatty acid and phospholipids metabolism). Many phages, prophages and transposons related genes were down regulated by growth rate suggesting genome plasticity to be involved in the adaptation to slow growth. The growth rate response was compared to carbon and amino-acid starvation transcriptomic responses, revealing constant and significant involvement of growth rate regulations in these two stressful conditions (overlap 26%). Although stringent response mechanism is considered as the one governing growth deceleration in bacteria, the rigorous comparison of the two transcriptomic responses clearly indicated the mechanisms are distinct. Moreover it was established that genes positively regulated by growth rate are preferentially located in the vicinity of replication origin while those negatively regulated are mainly encountered at the opposite. This result demonstrates the often neglected relationship between genes expression and their location on chromosome. Keywords: growth rate impact, continuous cultures Continuous cultivation of Lactococcus lactis IL1403 were carried out on a chemically defined medium and under controlled conditions (30 °C, pH 6.6, nitrogen atmosphere). Cell samples were harvested at steady state. Total RNA was extracted from these samples and radiolabelled cDNA were prepared and hybridized on nylon arrays. 1948 amplicons specific of Lactococcus lactis IL1403 genes were spotted twice on the array. Samples corresponding to various growth rates were analyzed simultaneously and 3 independent repetitions were performed.