Influence of sodium ion on heavy metal-induced inhibition of light-regulated proton efflux and active carbon uptake in the cyanobacterium Anabaena flos-aquae

S. K. Sharma, D. P. Singh, H. D. Shukla, Anwar Ahmad, P. S. Bisen

Research output: Contribution to journalArticlepeer-review

Abstract

The light-induced proton efflux and active carbon uptake are inhibited by mercury and cadmium ions in Anabaena flos-aquae. The inhibitory effects of these heavy metal ions are reversed by 40 mM concentration of sodium. Here we report that light-induced proton efflux is sodium-dependent which leads to a characteristic enhancement in the rate of photosynthetic oxygen generation and carbon fixation. A low concentration (10 μM) of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) significantly inhibited the rate of oxygen generation while 10 μM carbonyl cyanide-m-chlorophenylhydrazone (CCCP) completely blocked the oxygen generation activity in the organism. The chlorophyll-a fluorescence yield indicates that little fluorescence quenching occurred in the absence of sodium ion. Increasing the extracellular sodium ion accelerated both the initial rate and the extent of fluorescence quenching. These results support the assumption that metal-induced inhibition of the photosynthetic machinery may be mediated by the movement of protons.

Original languageEnglish (US)
Pages (from-to)707-711
Number of pages5
JournalWorld Journal of Microbiology and Biotechnology
Volume17
Issue number7
DOIs
StatePublished - 2001

Keywords

  • Anabaena flos-aquae
  • Carbon fixation
  • Electron transport chain
  • Heavy metal
  • Oxygen generation
  • Proton efflux

ASJC Scopus subject areas

  • Biotechnology
  • Physiology
  • Applied Microbiology and Biotechnology

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