Braunschweig University of Technology

About: Braunschweig University of Technology is a education organization based out in Braunschweig, Germany. It is known for research contribution in the topics: Population & Computer science. The organization has 13268 authors who have published 26707 publications receiving 611590 citations.

How Pseudomonas aeruginosa adapts to various environments: a metabolomic approach.

Abstract: Summary In addition to transcriptome and proteome studies, metabolome analysis represents a third complementary approach to identify metabolic pathways and adaptation processes. In order to elucidate basic principles of metabolic versatility of Pseudomonas aeruginosa, we investigated the metabolome profiles of two genetically and morphologically divergent strains, the reference strain PAO1 and the mucoid clinical isolate TBCF10839 in exponential growth and stationary phase in six different carbon sources (cadaverine, casamino acids, citrate, glucose, succinate and tryptone). Both strains exhibited strong similarities in mode of growth; the metabolite patterns were mainly defined by the growth condition. Besides this adaptive response, a basic core metabolism shapes the P. aeruginosa metabolome, independent of growth phase, carbon source and genetic background. This core metabolism includes pathways related to the central energy and amino acid metabolism. These consistently utilized metabolic pathways are closely related to glutamate which represents a dominant metabolite in all conditions analysed. In nutrient-depleted media of stationary phase cultures, P. aeruginosa maintains a specific repertoire of metabolic pathways that are related to the carbon source formerly available. This specified adaptation strategy combined with the invariant basic core metabolism may represent a fundamental requirement for the metabolic versatility of this organism.

The evaporation method: Extending the measurement range of soil hydraulic properties using the air-entry pressure of the ceramic cup

Abstract: Knowledge of hydraulic functions is required for various hydrological and plant-physiologicalstudies. The evaporation method is frequently used for the simultaneous determination ofhydraulic functions of unsaturated soil samples, i.e. , the water-retention curve and hydraulic-conductivity function. All methodic variants of the evaporation method suffer from the limitationthat the hydraulic functions can only be determined to a mean tension of ≈ 60 kPa. This iscaused by the limited measurement range of the tensiometers of typically 80 kPa on the dryend. We present a new, cost- and time-saving approach which overcomes this restriction. Usingthe air-entry pressure of the tensiometer’s porous ceramic cup as additional defined tensionvalue allows the quantification of hydraulic functions up to close to the wilting point. The proce-dure is described, uncertainties are discussed, and measured as well as simulated test resultsare presented for soil samples of various origins, different textures (sand, loam, silt, clay, andpeat) and variable dry bulk density. The experimental setup followed the system HYPROP whichis a commercial device with vertically aligned tensiometers that is optimized to perform evapora-tion measurements. During the experiment leaked water from the tensiometer interior wets thesurrounding soil of the tensiometer cup and can lead to a tension retardation as shown by simu-lation results. This effect is negligible when the tensiometers are embedded vertically. For coar-sely textured soils and horizontal tensiometer alignment, however, the retardation must be con-sidered for data evaluation.