Elevated pCO2 causes a shift towards more toxic microcystin variants in nitrogen limited Microcystis aeruginosa.

TY - JOUR

T1 - Elevated pCO2 causes a shift towards more toxic microcystin variants in nitrogen limited Microcystis aeruginosa.

AU - Liu, J.

AU - van Oosterhout, Elmer

AU - Faassen, E.J.

AU - Lurling, M.

AU - Helmsing, N.R.

AU - Van de Waal, D.B.

N1 - 5997, AqE; Data archiving: data archived at MDA

PY - 2016

Y1 - 2016

N2 - Elevated pCO2 may promote phytoplankton growth, and potentially alleviate carbon limitation during dense blooms. Under nitrogen-limited conditions, elevated pCO2 may furthermore alter the phytoplankton carbon: nitrogen (C:N) balance and thereby the synthesis of secondary metabolites, such as cyanobacterial toxins. A common group of these toxins are microcystins, with variants that not only differ in C:N stoichiometry, but also in toxicity. Here, we hypothesized that elevated pCO2 will increase the cellular C:N ratios of cyanobacteria, thereby promoting the more toxic microcystin variants with higher C:N ratios. To test this hypothesis, we performed chemostat experiments under nitrogen-limited conditions, exposing three Microcystis aeruginosa strains to two pCO2 treatments: 400 and 1200 μatm. Biomass, cellular C:N ratios and total microcystin contents at steady state remained largely unaltered in all three strains. Across strains and treatments, however, cellular microcystin content decreased with increasing cellular C:N ratios, suggesting a general stoichiometric regulation. Furthermore, as predicted, microcystin variants with higher C:N ratios generally increased with elevated pCO2, while the variant with a low C:N ratio decreased. Thus, elevated pCO2 under nitrogen-limited conditions may shift the cellular microcystin composition towards the more toxic variants. Such CO2 driven changes may have consequences for the toxicity of Microcystis blooms.

AB - Elevated pCO2 may promote phytoplankton growth, and potentially alleviate carbon limitation during dense blooms. Under nitrogen-limited conditions, elevated pCO2 may furthermore alter the phytoplankton carbon: nitrogen (C:N) balance and thereby the synthesis of secondary metabolites, such as cyanobacterial toxins. A common group of these toxins are microcystins, with variants that not only differ in C:N stoichiometry, but also in toxicity. Here, we hypothesized that elevated pCO2 will increase the cellular C:N ratios of cyanobacteria, thereby promoting the more toxic microcystin variants with higher C:N ratios. To test this hypothesis, we performed chemostat experiments under nitrogen-limited conditions, exposing three Microcystis aeruginosa strains to two pCO2 treatments: 400 and 1200 μatm. Biomass, cellular C:N ratios and total microcystin contents at steady state remained largely unaltered in all three strains. Across strains and treatments, however, cellular microcystin content decreased with increasing cellular C:N ratios, suggesting a general stoichiometric regulation. Furthermore, as predicted, microcystin variants with higher C:N ratios generally increased with elevated pCO2, while the variant with a low C:N ratio decreased. Thus, elevated pCO2 under nitrogen-limited conditions may shift the cellular microcystin composition towards the more toxic variants. Such CO2 driven changes may have consequences for the toxicity of Microcystis blooms.

KW - national

UR - http://mda.vliz.be/mda/directlink.php?fid=VLIZ_00000444_5889fe53db108

U2 - 10.1093/femsec/fiv159

DO - 10.1093/femsec/fiv159

M3 - Article

SN - 0168-6496

VL - 92

JO - FEMS Microbiology Ecology

JF - FEMS Microbiology Ecology

IS - 2

M1 - fiv159

ER -