Search results for "DESICCATION"
showing 10 items of 91 documents
Dehydration and crystallization of trehalose and sucrose glasses containing carbonmonoxy-myoglobin
1999
We report a study wherein we contemporarily measured 1) the dehydration process of trehalose or sucrose glasses embedding carbonmonoxy-myoglobin (MbCO) and 2) the evolution of the A substates in saccharide-coated MbCO. Our results indicate that microcrystallization processes, sizeably different in the two saccharides, take place during dehydration; moreover, the microcrystalline structure is maintained unless the dry samples are equilibrated with a humidity >/=75% (>/=60%) at 25 degrees C for the trehalose (sucrose) sample. The evolution of the parameters that characterize the A substates of MbCO indicates that 1) the effects of water withdrawal are analogous in samples dried in the presenc…
In Situ X-Ray Tomography Imaging of Soil Water and Cyanobacteria From Biological Soil Crusts Undergoing Desiccation
2018
Biological soil crusts (biocrusts) are millimeter-sized microbial communities developing on the topsoils of arid lands that cover some 12% of Earth’s continental area. Biocrusts consist of an assemblage of mineral soil particles consolidated into a crust by microbial organic polymeric substances that are mainly produced by the filamentous bundle-forming cyanobacteria, among which Microcoleus vaginatus is perhaps the most widespread. This cyanobacterium is the primary producer for, and main architect of biocrusts in many arid soils, sustaining the development of a diverse microbial community. Biocrusts are only active when wet, and spend most of their time in a state of desiccated quiescence…
Effect of ultrasound pre-treatment and drying method on specialized metabolites of honeyberry fruits (Lonicera caerulea var. kamtschatica).
2019
Abstract Honeyberries are rich in various nutrients (eg. minerals, and vitamins) and bioactive compounds (eg. polyphenols). The aim of the study was to evaluate the impact of ultrasound (USN) pre-treatment (100% power at 37 kHz) at 40 °C for 3 min and drying techniques (conduction or vacuum) on nutritional composition and bioactive compounds of honeyberry fruits. The evaluation of dried barriers revealed that both USN pre-treatment and drying techniques affected the composition of the final product. The highest vitamin C content (1.067–1.187 mg 100 g−1 DM) was found in fruit samples pre-treated by USN, regardless of the drying technology used. The highest total phenol (2.445 mg GAE 100 g−1 …
Oxidative stress responses and lipid peroxidation damage are induced during dehydration in the production of dry active wine yeasts.
2009
The tolerance of the yeast Saccharomyces cerevisiae to desiccation is important for the use of this microorganism in the wine industry, since active dry wine yeast is routinely used as starter for must fermentations. Many studies have shown the complexity of the cellular effects caused by water loss, including oxidative injuries on macromolecular components. However the technological interest of yeast drying was not addressed in those studies, and the dehydration conditions were far from the industrial practice. In the present study a molecular approach was used to characterize the relevant injuring conditions during pilot plant dehydrations under two different drying temperatures (i.e., 35…
Effect of water content and temperature on seed longevity of seven Brassicaceae species after 5 years of storage.
2014
Maximising seed longevity is crucial for genetic resource preservation and longevity of orthodox seeds is determined by environmental conditions (water content and temperature). The effect of water content (down to 0.01 g·H₂O·g(-1) ) on seed viability was studied at different temperatures for a 5-year storage period in taxonomically related species. Seeds of seven Brassicaceae species (Brassica repanda, Eruca vesicaria, Malcolmia littorea, Moricandia arvensis, Rorippa nasturtium-aquaticum, Sinapis alba, Sisymbrium runcinatum) were stored at 48 environments comprising a combination of eight water contents, from 0.21 to 0.01 g·H₂O·g(-1) DW and six temperatures (45, 35, 20, 5, -25, -170 °C). S…
Identification and transcriptional profile of Lactobacillus paracasei genes involved in the response to desiccation and rehydration
2020
International audience; Lactobacillus paracasei is able to persist in a variety of natural and technological environments despite physico-chemical perturbations, in particular alternations between desiccation and rehydration. However, the way in which it adapts to hydric fluctuations and the genetic determinants involved are not clearly understood. To identify the genes involved in adaptation to desiccation, an annotated library of L. paracasei random transposon mutants was screened for viability after desiccation (25% relative humidity, 25 °C). We found 16 genes that have not been described as being involved in this response. Most of them are linked to either the transport of molecules or …
The organic air pollutant cumene hydroperoxide interferes with NOantioxidant role in rehydrating lichen
2013
Organic pollutants effects on lichens have not been addressed. Rehydration is critical for lichens, a burst of free radicals involving NO occurs. Repeated dehydrations with organic pollutants could increase oxidative damage. Our aim is to learn the effects of cumene hydroperoxide (CP) during lichen rehydration using Ramalina farinacea (L.) Ach., its photobiont Trebouxia spp. and Asterochloris erici. Confocal imaging shows intracellular ROS and NO production within myco and phycobionts, being the chloroplast the main source of free radicals. CP increases ROS, NO and lipid peroxidation and reduces chlorophyll autofluorescence, although photosynthesis remains unaffected. Concomitant NO inhibit…
Desiccation by Exposure to Space Vacuum or Extremely Dry Deserts: Effect on Microorganisms
2003
General Limits of Growth at Low Water Activities Dormant Life Molecular Events Induced by Desiccation Survival at Extremely Low Water Activity Survival Under Extremely Dry Desert Conditions Keywords: anhydrobiosis; desiccation; extreme environments; freeze-drying; panspermia thesis; space: survival in space; space vacuum; water activity
Preparation of fungal conidia impacts their susceptibility to inactivation by ethanol vapours.
2009
Abstract A common protocol employed for the preparation of conidia employs flooding a fungal colony grown on semi-solid media under optimum conditions with an aqueous solution. In contrast, conidia produced in a natural environment are usually not hydrated when disseminated in air and can be produced under water stress. In order to simulate the latter conditions, cultures were grown at different water activities and conidia were dry-harvested on the lid by turning the dishes upside-down then gently tapping the bottom of the box. This study aimed at assessing the effect of the preparation of fungal conidia on their inactivation by ethanol vapours. Firstly ethanol vapours (either 0.30 or 0.45…
Hydration and dehydration kinetics of xylazine hydrochloride
2009
From the experiments where mixture of xylazine hydrochloride hydrate H and anhydrous X were held at constant conditions, the stable form of xylazine hydrochloride can be found out. To determine equilibrium relative humidity, the unstable form of xylazine hydrochloride was inserted in thermostated humidity chamber and its weight was recorded by weighing the sample outside the chamber. The kinetic model and the rate constant for each condition were determined. The rate constants give information regarding the speed of the process at every experimentally used relative humidity. Thus using the data in coordinates k – p for each temperature it is possible to determine the water vapor pressure of…