Possible roles of reactive chlorine II: assessing biotic chlorination as a way for organisms to handle oxygen stress


  • Per Bengtson,

    1. Department of Biology – Microbial Ecology, Lund University, The Ecology Building, Lund SE-223 62, Sweden
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  • David Bastviken,

    1. Water and Environmental Studies, Linköping University, Linköping SE-581 83, Sweden
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  • Gunilla Öberg

    Corresponding author
    1. Institute for Resources, Environment and Sustainability, University of British Columbia, 429-2202 Main Mall, Vancouver, British Columbia, Canada V6T 1Z4
      E-mail goberg@ires.ubc.ca; Tel. (+1) 604 306 9900; Fax (+1) 604 822 9250.
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E-mail goberg@ires.ubc.ca; Tel. (+1) 604 306 9900; Fax (+1) 604 822 9250.


Natural formation of organically bound chlorine is extensive in many environments. The enzymes associated with the formation of chlorinated organic matter are produced by a large variety of organisms. Little is known about the ecological role of the process, the key question being: why do microorganisms promote chlorination of organic matter? In a recent paper we discuss whether organic matter chlorination may be a result of antagonistic interactions among microorganisms. In the present paper we evaluate whether extracellular microbial formation of reactive chlorine may be used as a defence against oxygen stress, and we discuss whether this process is likely to contribute to the formation of chlorinated organic matter. Our analysis suggests that periodic exposure to elevated concentrations of reactive oxygen species is a common denominator among the multitude of organisms that are able to enzymatically catalyse formation of reactive chlorine. There is also some evidence suggesting that the production of such enzymes in algae and bacteria is induced by oxygen stress. The relative contribution from this process to the extensive formation of chlorinated organic matter in natural environments remains to be empirically assessed.