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Title: Viability of Cladosporium herbarum spores under 157 nm laser and vacuum ultraviolet irradiation, low temperature (10 K) and vacuum

Ultraviolet photons can damage microorganisms, which rarely survive prolonged irradiation. In addition to the need for intact DNA, cell viability is directly linked to the functionality of the cell wall and membrane. In this work, Cladosporium herbarum spore monolayers exhibit high viability (7%) when exposed to 157 nm laser irradiation (412 kJm⁻²) or vacuum-ultraviolet irradiation (110–180 nm) under standard pressure and temperature in a nitrogen atmosphere. Spore viability can be determined by atomic-force microscopy, nano-indentation, mass, μ-Raman and attenuated reflectance Fourier-transform far-infrared spectroscopies and DNA electrophoresis. Vacuum ultraviolet photons cause molecular damage to the cell wall, but radiation resistance in spores arises from the activation of a photon-triggered signaling reaction, expressed via the exudation of intracellular substances, which, in combination with the low penetration depth of vacuum-ultraviolet photons, shields DNA from radiation. Resistance to phototoxicity under standard conditions was assessed, as was resistance to additional environmental stresses, including exposure in a vacuum, under different rates of change of pressure during pumping time and low (10 K) temperatures. Vacuum conditions were far more destructive to spores than vacuum-ultraviolet irradiation, and UV-B photons were two orders of magnitude more damaging than vacuum-ultraviolet photons. The viability of irradiated spores was also enhanced atmore » 10 K. This work, in addition to contributing to the photonic control of the viability of microorganisms exposed under extreme conditions, including decontamination of biological warfare agents, outlines the basis for identifying bio-signaling in vivo using physical methodologies.« less
Authors:
; ; ; ;  [1] ; ; ; ;  [2] ;  [3]
  1. National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635 (Greece)
  2. N.C.S.R. “Demokritos”, Institute for Nuclear and Radiological Sciences, Energy, Technology and Safety, Patriarchou Gregoriou Str. Aghia Paraskevi, Athens 15310 (Greece)
  3. University of Athens, Faculty of Biology, Department of Cell Biology and Biophysics, Athens 15784 (Greece)
Publication Date:
OSTI Identifier:
22305970
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 63 RADIATION, THERMAL, AND OTHER ENVIRONMENTAL POLLUTANT EFFECTS ON LIVING ORGANISMS AND BIOLOGICAL MATERIALS; ABSORPTION SPECTROSCOPY; ATOMIC FORCE MICROSCOPY; BIOLOGICAL EFFECTS; BIOLOGICAL WARFARE AGENTS; DNA; ELECTROPHORESIS; FAR INFRARED RADIATION; FOURIER TRANSFORMATION; LASER RADIATION; MEMBRANES; MICROORGANISMS; PENETRATION DEPTH; PHOTONS; RAMAN EFFECT; SPORES; STRESSES; TEMPERATURE RANGE 0000-0013 K; ULTRAVIOLET RADIATION; VIABILITY