Characterization of microcystin-LR removal process in the presence of probiotic bacteria

S. M.K. Nybom*, D. Dziga, J. E. Heikkilä, T. P.J. Kull, S. J. Salminen, J. A.O. Meriluoto

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

25 Citations (Scopus)

Abstract

Toxic cyanobacteria have been reported in lakes and reservoirs in several countries. The presence of toxins in drinking water creates a potential risk of toxin transference for water consumers. Besides chemical and physical methods of cyanotoxin removal from water, biodegradation methods would be useful. The aim of the current study was to identify bacterial removal mechanisms of the hepatotoxin microcystin-LR. This was studied by testing the hypothesis of enzymatic degradation of microcystin-LR in the presence of probiotic lactic acid bacterial and bifidobacterial strains and the participation of the proteolytic system of the bacteria in this process. The results suggest that extracellularly located cell-envelope proteinases are involved in the decomposition of microcystin-LR. In particular, a correlation between proteolytic activity and microcystin removal was found and both these parameters were dependent on glucose as an energy source. In addition, EDTA, which was indicated as a main inhibitor of proteinases of the investigated strain, was shown to limit the rate of microcystin removal. The removal of microcystins was shown to be different from the known microcystin-degradation pathway of Sphingomonas. 14C-labeled microcystin was not found inside the cells and bacterial cell extracts were not able to remove the toxin, which supports the involvement of extracellularly located proteinases. The results confirm the hypothesis of enzymatic degradation of microcystins in the presence of probiotic bacteria.

Original languageEnglish
Pages (from-to)171-181
Number of pages11
JournalToxicon
Volume59
Issue number1
DOIs
Publication statusPublished - Jan 2012
MoE publication typeA1 Journal article-refereed

Keywords

  • Bifidobacterium
  • Biodegradation
  • Lactobacillus
  • Microcystin-LR removal
  • Probiotic bacteria
  • Proteolytic activity

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