Water Dynamics in Shewanella oneidensis at Ambient and High Pressure using Quasi-Elastic Neutron Scattering

Abstract

Quasielastic neutron scattering (QENS) is an ideal technique for studying water transport and relaxation dynamics at pico- to nanosecond timescales and at length scales relevant to cellular dimensions. Studies of high pressure dynamic effects in live organisms are needed to understand Earth’s deep biosphere and biotechnology applications. Here we applied QENS to study water transport in Shewanella oneidensis at ambient (0.1 MPa) and high (200 MPa) pressure using H/D isotopic contrast experiments for normal and perdeuterated bacteria and buffer solutions to distinguish intracellular and transmembrane processes. The results indicate that intracellular water dynamics are comparable with bulk diffusion rates in aqueous fluids at ambient conditions but a significant reduction occurs in high pressure mobility. We interpret this as due to enhanced interactions with macromolecules in the nanoconfined environment. Overall diffusion rates across the cell envelope also occur at similar rates but unexpected narrowing of the QENS signal appears between momentum transfer values Q = 0.7–1.1 Å−1 corresponding to real space dimensions of 6–9 Å. The relaxation time increase can be explained by correlated dynamics of molecules passing through Aquaporin water transport complexes located within the inner or outer membrane structures.

Anticancer drug impact on DNA – a study by neutron spectroscopy coupled with synchrotron-based FTIR and EXAFS

“…the 2 Â IC 50 level), for a 48 h exposure time. A multidisciplinary experimental approach was followed, through the application of: (i) quasi-elastic neutron scattering (QENS), suitable for directly accessing different spatially resolved dynamical processes (at a subnanometer lengthscale and subnanosecond timescale), under distinct conditions, mainly for hydrogen-rich systems; 25,[29][30][31] (ii) synchrotron-radiation Fourier-Transform Infrared Spectroscopy-Attenuated Total Reflectance (SR-FTIR-ATR), recognized as a cutting-edge non-destructive tool for obtaining spectral signatures of molecular components in biological samples, so as to relate structural to functional data; 32,33 and (iii) synchrotron-based Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near-Edge Structure (XANES), which are methods of choice for obtaining detailed information on the local structure of bioinorganic non-crystalline materials. 34,35 Water supports vital biochemical processes in living organisms, and is responsible for the maintenance of the functional threedimensional architecture of biopolymers through a tight interplay within their hydration shells.…”

Experimental and Simulation Efforts in the Astrobiological Exploration of Exooceans

“…The growth experiments were carried out over a range of pressure up to 90 bar and the experiments were performed with either a H 2 /CO 2 (4:1) gas phase, a H 2 /CO 2 /N 2 (4:1:5), or, as in the final experiments, with a N 2 /H 2 /CO 2 /CO/C 2 H 4 (32.5:55:6.5:3:3) mixture. At higher pressures above 1000 bar, microbial survival is investigated using a diamond anvil (e.g., Foglia et al 2016;Schuerger and Nicholson 2016;Hazael et al 2017). For example, the effect of high pressure (0.0006-0.01 Mbar) on the physiology and metabolic activity of Shewanella oneidensis and Escherichia coli was investigated (Sharma et al 2002).…”

“…These experiments include studies that examine material properties under subsurface conditions, e.g. the dynamics of ices, and high-pressure facilities used for both biotic (studies regarding microbial survival and biosignature production: Taubner et al 2018Taubner et al , 2019Foglia et al 2016;Schuerger and Nicholson 2016;Hazael et al 2017;Sharma et al 2002) and abiotic settings (studies exploring ice-water and water-silicate interactions: Vance and Brown 2008, 2013Mantegazzi et al 2012Mantegazzi et al , 2013. Further, investigations into environmental gradients are performed to broaden our understanding of the physical conditions on these icy worlds (More-Mutch et al submitted).…”

Towards Determining Biosignature Retention in Icy World Plumes

“…The potential habitability of icy moons has led to studies addressing possible microbial survival and growth [17][18][19][20][21][22], as well as estimates of biomass concentrations [23][24][25] in these environments. The results show that, under certain conditions (degree of convection, mantle rheology, etc.…”