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BACTERIAL PHOTOPROTECTION THROUGH EXTRACELLULAR CADMIUM SULFIDE CRYSTALLITES
Author(s) -
Holmes Justin D.,
Smith Peter R.,
EvansGowing Richard,
Richardson David J.,
Russell David A.,
Sodeau John R.
Publication year - 1995
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1995.tb02403.x
Subject(s) - photoprotection , extracellular , chemistry , cadmium sulfide , crystallite , cadmium , extracellular polymeric substance , environmental chemistry , biophysics , microbiology and biotechnology , bacteria , biology , biochemistry , inorganic chemistry , biofilm , crystallography , photosynthesis , organic chemistry , genetics
Ultraviolet light and the heavy metal, cadmium, both have toxic effects on many microorganisms. In this communication we describe a method by which the bacterium Klebsiella aerogenes surmounts both problems using one biological process: the synthesis of cadmium sulfide (CdS) crystallites. These semiconductor particles absorb radiation in the UV spectral region and therefore, when K. aerogenes produces extracellular CdS material in response to environments containing cadmium ions, a photoprotective layer is formed. The effect of UVA radiation on cultures of Klebsiella aerogenes was monitored using electron microscopy, energy‐dispersive X‐ray analysis and electronic spectroscopy. The results show that at wavelengths 320 nm Λ 400 nm, a photoprotection period of between 4 and 6 h is induced, which eventually fails due to photodegradation of the semiconductor layer to metallic cadmium and elemental sulfur.