Combined treatment of toxic cyanobacteria Microcystis aeruginosa with hydrogen peroxide and microcystin biodegradation agents results in quick toxin elimination

摘要

Under some conditions the growth of toxic cyanobacteriamust be controlled by treatment with algicidal compounds.Hydrogen peroxide has been proposed as anefficient and relatively safe chemical which can removecyanobacteria from the environment selectively, withoutaffecting other microorganisms. However, the uncontrolledrelease of secondary metabolites, includingtoxins may occur after such a treatment. Our proposalpresented in this paper concerns fast biodegradation ofmicrocystin released after cell lysis induced by hydrogenperoxide. The effectiveness of both, Sphingomonassp. and heterologously expressed MlrA enzyme, in theremoval of the toxin from Microcystis aeruginosa culturewas investigated. The results indicate that neitherSphingomonas cells nor MlrA are affected by hydrogenperoxide at the concentrations which stop the growthof cyanobacteria. A several-fold reduction in microcystinlevels was documented in the presence of these agentswith biodegradation ability. Our results provide evidencethat such a combined treatment of water reservoirsdominated by microcystin-producing cyanobacteria maybe a promising alternative which allows fast eliminationof both, the bloom forming species and toxins, from theenvironment.