Effect of Chain Unsaturation and Temperature on Oxygen Diffusion Through Lipid Membranes from Simulations.

Rafts are nanoscale ordered domains in biological membranes that are rich in saturated phospholipids. In this study, the influence of chain unsaturation and temperature on oxygen diffusion through lipid membranes is examined using advanced computational modeling. The studied phospholipids with increasing unsaturation are: 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC).

Membrane Permeability: Characteristic Times and Lengths for Oxygen and a Simulation-Based Test of the Inhomogeneous Solubility-Diffusion Model.

The balance of normal and radial (lateral) diffusion of oxygen in phospholipid membranes is critical for biological function. Based on the Smoluchowski equation for the inhomogeneous solubility-diffusion model, Bayesian analysis (BA) can be applied to molecular dynamics trajectories of oxygen to extract the free energy and the normal and radial diffusion profiles. This paper derives a theoretical formalism to convert these profiles into characteristic times and lengths associated with entering, escaping, or completely crossing the membrane.

The effect of the native bacterial community structure on the predictability of E. coli O157:H7 survival in manure-amended soil.

Aims: The survival capability of pathogens like Escherichia coli O157:H7 in manure-amended soil is considered to be an important factor for the likelihood of crop contamination. The aim of this study was to reveal the effects of the diversity and composition of soil bacterial community structure on the survival time (ttd) and stability (irregularity, defined as the intensity of irregular dynamic changes in a population over time) of an introduced E. coli O157:H7 gfp-strain were investigated for 36 different soils by means of bacterial PCR-DGGE fingerprints.

Manure-amended soil characteristics affecting the survival of E. coli O157:H7 in 36 Dutch soils.

The recent increase in foodborne disease associated with the consumption of fresh vegetables stresses the importance of the development of intervention strategies that minimize the risk of preharvest contamination. To identify risk factors for Escherichia coli O157:H7 persistence in soil, we studied the survival of a Shiga-toxin-deficient mutant in a set of 36 Dutch arable manure-amended soils (organic/conventional, sand/loam) and measured an array of biotic and abiotic manure-amended soil characteristics. The Weibull model, which is the cumulative form of the underlying distribution of individual inactivation kinetics, proved to be a suitable model for describing the decline of E.

Wave-like distribution patterns of gfp-marked Pseudomonas fluorescens along roots of wheat plants grown in two soils.

Culturable rhizosphere bacterial communities had been shown to exhibit wave-like distribution patterns along wheat roots. In the current work we show, for the first time, significant wave-like oscillations of an individual bacterial strain, the biocontrol agent Pseudomonas fluorescens 32 marked with gfp, along 3-week-old wheat roots in a conventionally managed and an organically managed soil. Significant wave-like fluctuations were observed for colony forming units (CFUs) on selective media and direct fluorescent counts under the microscope.