World Journal of Microbiology and Biotechnology

, Volume 17, Issue 1, pp 15–22

Antialgal activity of a hepatotoxin-producing cyanobacterium, Microcystis aeruginosa

  • Dhananjaya P. Singh
  • M.B. Tyagi
  • Arvind Kumar
  • J.K. Thakur
  • Ashok Kumar
Article

DOI: 10.1023/A:1016622414140

Cite this article as:
Singh, D.P., Tyagi, M., Kumar, A. et al. World Journal of Microbiology and Biotechnology (2001) 17: 15. doi:10.1023/A:1016622414140

Abstract

Antimicrobial activity of toxin produced by a freshwater bloom-forming cyanobacterium Microcystis aeruginosa has been studied. When tested against certain green algae, cyanobacteria, heterotrophic bacteria and fungi, the toxin inhibited growth of only green algae and cyanobacteria. The toxin has been partially purified employing Thin layer chromatography (TLC) and High-performance liquid chromatography (HPLC) techniques and appears to be microcystin-LR (leucine–arginine). Both crude and purified toxins showed toxicity to mice, the clinical symptoms in test mice being similar to those produced by hepatotoxin. Purified toxin at a concentration of 50 μg ml−1 caused complete inhibition of growth followed by cell lysis in Nostoc muscorum and Anabaena BT1 after 6 days of toxin addition. Addition of toxin (25 μg ml−1) to the culture suspensions of the Nostoc and Anabaena strains caused instant and drastic loss of O2 evolution. Furthermore a marked reduction (about 87%) in the 14CO2 uptake was also observed at a concentration of 50 μg ml−1. Besides its inhibitory effects on photosynthetic processes, M. aeruginosa toxin (50 μg ml−1) also caused 90% loss of nitrogenase activity after 8 h of its addition. Experiments performed with 14C-labelled toxin indicate that the toxin uptake by cyanobacterial cells occurs both in light and dark. These results demonstrate that the toxin is strongly algicidal and point to the possibility that it may have an important role in establishment and maintenance of toxic blooms of M. aeruginosa in freshwater ecosystems. The relative significance of the hepatotoxic effect and the algicidal effect of the toxin is discussed with reference both to survival and dominance of M. aeruginosa in nature.

AntialgalcyanobacteriamicrocystinMicrocystistoxin

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Dhananjaya P. Singh
    • 1
  • M.B. Tyagi
    • 2
  • Arvind Kumar
    • 1
  • J.K. Thakur
    • 1
  • Ashok Kumar
    • 1
  1. 1.Microbial Biotechnology Unit, School of BiotechnologyBanaras Hindu UniversityVaranasi –India
  2. 2.Department of Botany, Mahila MahavidyalayaBanaras Hindu UniversityVaranasi –India