Isolation, Identification, and Characterization of the Algicidal Micromycete Penicillium chrysogenum SR-1.3

Abstract

The novel strain SR-1.3 with algicidal properties and the ability to remove microcystin-LR (MC-LR) has been isolated from the water of Lake Sestroretsk Razliv during active cyanobacteria vegetation. Based on the morphological and cultural characteristics and the results of sequencing the ITS region of DNA, strain SR-1.3 was identified as Penicillium chrysogenum. The SR-1.3 strain exhibits algicidal activity against cyanobacteria and green algae. A dose-dependent and species-specific nature of the algicidal action of the P. chrysogenum SR-1.3 strain has been established. Cyanobacteria show the highest sensitivity to strain SR-1.3. The complete lysis (100%) of cyanobacteria cells is observed when 10% (vol) of the culture liquid or the micromycete filtrate are added to the medium. The algicidal effect of strain SR-1.3 on green algae is 30–70%, depending on the culture. According to the level of sensitivity to the algicidal effect of SR-1.3, the test cultures can be arranged in the series Planktothrix agardhii > Microcystis aeruginosa > Aphanizomenon flos-aquae = Anabaena cylindrica > Scenedesmus quadricauda > Oocystis parva. The inhibitory effect of the strain SR-1.3 mycelium on cyanobacteria and green algae growth does not exceed 3–6%. Based on the results, a conclusion was made about the indirect mechanism of the algicidal action of P. chrysogenum SR-1.3 by excretion into the medium of metabolites that inhibit and/or lyse cells of cyanobacteria and green algae. When toxigenic strains M. aeruginosa and P. agardhii are cultivated on a medium containing exometabolites of strain SR-1.3, the concentrations of microcystins in the medium decreases 3.3 and 1.8 times, respectively, compared with control variants. The ability of P. chrysogenum SR-1.3 to remove the highly toxic MC-LR from the cultivation medium is revealed. The MC-LR content is found to decrease from 1.2 to 0.79 μg/mL over 48 h during the cultivation of strain SR-1.3 on a medium with microcystin.