Experimental investigation of the detection mechanism in WSi nanowire superconducting single photon detectors

Quantum Matter and Optic

Transcriptome response of Lactobacillus plantarum to global regulator deficiency, stress and other environmental conditions

Lactobacillus plantarum is a lactic acid bacterium encountered in a variety of food and feed fermentations and as a natural inhabitant of human gastrointestinal tract. To survive in these niches and to maintain its capability, L. plantarum has to respond to numerous changing conditions and the cellular processes involved in these responses are frequently regulated at the transcriptional level. For this reason the transcriptome of a cell is of interest, as it contains information about the transcriptional response of individual genes. Transcriptomic approaches allow elucidation of transcriptional behaviour of all genes at once and are therefore a powerful tool to study all the transcriptional response of a bacterium to differential conditions. The complete genome of L. plantarum was sequenced and putative genes were identified and annotated, allowing design and production of a full genome amplicon based microarray. Using this array, the transcriptional response of L. plantarum to a variety of conditions could be identified. The regulon of sigma factor 54 (σ54) was elucidated and consisted of a single operon encoding a mannose phosphotransferase system (PTS). This transport system was found to be the only functional mannose transporter in L. plantarum. Additionally, a glucose transport function was established for this PTS and deletion of the PTS led to an increase of the intracellular phosphoenolpyruvate (PEP) concentration in resting cells, indicating an important role of this glucose transport system in metabolic control of carbohydrate metabolism. The mannose PTS was also found to play an important role in hydrogen peroxide caused oxidative stress survival due to its robustness to oxidative stress. The impact of mild oxidative stress caused by aerobic growth was elucidated by comparing an aerobic grown culture with an anaerobic grown culture. The results led to the identification of the underlying mechanism of an observed growth stagnation, and subsequent adjustments of fermentation conditions led to overcome the stagnation. The role of the global regulator of catabolite control (CcpA) was determined throughout the whole growth curve, showing a global role for this regulator in catabolite control. Additional studies with different carbon sources confirmed this global role of CcpA and suggested further fine-tuning of regulation by local regulators. <br/