Enhanced resistance of co-existing toxigenic and non-toxigenic Microcystis aeruginosa to pyrogallol compared with monostrains. (March 2020)

• Record Type: Journal Article
• Authors: Gao, Yunni; Lu, Jing; Orr, Philip T.; Chuang, Ann; Franklin, Hannah M.; Burford, Michele A.
• Is Part Of: Toxicon. Volume 176(2020)
• Page Start: 47
• Page End: 54
• Publication Date: 2020-03
• Subjects: Co-existing strains -- Microcystis aeruginosa -- Pyrogallol -- Direct co-culture -- Dialysis co-culture; Toxins -- Periodicals; Venom -- Periodicals; 615.9
• DOI: 10.1016/j.toxicon.2020.01.013
• Languages: English
• ISSNs: 0041-0101

Abstract

Abstract: Cyanobacteria species are sensitive to many plant allelochemicals, such as pyrogallol. However, little attention has been paid to the relative effects of these xenobiotics on co-occurring toxigenic and non-toxigenic cyanobacterial strains, despite their co-existence in blooms. Hence, the responses of one toxigenic (TS2) and two non-toxigenic (NS1, NS2) Microcystis aeruginosa strains to pyrogallol were tested under three conditions: mono-culture and co-cultured either directly or separately by dialysis membrane. The study showed that the inhibitory effects of pyrogallol on the growth and photosynthetic yield (Fv/Fm) of either toxigenic or non-toxigenic M. aeruginosa strains were lower in direct and dialysis co-culture conditions than those in mono-culture conditions. This result indicated that chemical-mediated reciprocal effects occur between the co-existing toxigenic and non-toxigenic strains. The toxigenic M. aeruginosa strain was more sensitive to pyrogallol than the non-toxigenic strains in both mono- and co-culture systems, though whether this outcome is due to the former's toxigenic status is unclear. Intracellular microcystin-LR (MC-LR) concentrations of the toxigenic strain decreased after pyrogallol addition in both mono- and co-culture systems, whereas extracellular MC-LR concentrations increased. This finding may reflect the cell damage of M. aeruginosa because of the pyrogallol. At the same initial number of cells, the extracellular MC-LR concentration released from the same amount of TS2 cells in mono-culture was slightly higher than that in dialysis co-culture conditions. Overall, this study shows that plant allelochemicals may have the potential to reduce bloom toxicity by reducing the proportion of toxigenic cyanobacterial strains, and the effects of co-existing strains must be considered when assessing the effects of plant allelochemicals on target strains. Highlights: Lower pyrogallol toxicity to co-existing M. aeruginosa than mono-strains. Chemical-mediated reciprocal interaction of co-existing strains existed. Toxigenic M. aeruginosa was more sensitive to pyrogallol than non-toxigenic strain. Less intracellular microcystin-LR of toxigenic M. aeruginosa exposed to pyrogallol. More extracellular microcystin-LR of toxigenic M. aeruginosa exposed to pyrogallol.