Constructed wetland mesocosms improve the biodegradation of microcystin-LR and cylindrospermopsin by indigenous bacterial consortia

TY - JOUR

T1 - Constructed wetland mesocosms improve the biodegradation of microcystin-LR and cylindrospermopsin by indigenous bacterial consortia

AU - Thyssen, Lasse Ahrenkiel

AU - Martinez i Quer, Alba

AU - Arias, Carlos Alberto

AU - Ellegaard-Jensen, Lea

AU - Carvalho, Pedro N.

AU - Johansen, Anders

N1 - Publisher Copyright: © 2023 The Author(s)

PY - 2024/1

Y1 - 2024/1

N2 - Cyanobacterial blooms releasing harmful cyanotoxins, such as microcystin (MC) and cylindrospermopsin (CYN), are prominent threats to human and animal health. Constructed wetlands (CW) may be a nature-based solution for bioremediation of lake surface water containing cyanotoxins, due to its low-cost requirement of infrastructure and environmentally friendly operation. There is recent evidence that microcystin-LR (MC-LR) can efficiently be removed in CW microcosms where CYN degradation in CW is unknown. Likewise, the mechanistic background regarding cyanotoxins transformation in CW is not yet elucidated. In the present study, the objective was to compare MC-LR and CYN degradation efficiencies by two similar microbial communities obtained from CW mesocosms, by two different experiments setup: 1) in vitro batch experiment in serum bottles with an introduced CW community, and 2) degradation in CW mesocosms. In experiment 1) MC-LR and CYN were spiked at 100 µg L−1 and in experiment 2) 200 µg L−1 were spiked. Results showed that MC-LR was degraded to ≤1 µg L−1 within seven days in both experiments. However, with a markedly higher degradation rate constant in the CW mesocosms (0.18 day−1 and 0.75 day−1, respectively). No CYN removal was detected in the in vitro incubations, whereas around 50 % of the spiked CYN was removed in the CW mesocosms. The microbial community responded markedly to the cyanotoxin treatment, with the most prominent increase of bacteria affiliated with Methylophilaceae (order: Methylophilales, phylum: Proteobacteria). The results strongly indicate that CWs can develop an active microbial community capable of efficient removal of MC-LR and CYN. However, the CW operational conditions need to be optimized to achieve a full CYN degradation. To the best of our knowledge, this study is the first to report the ability of CW mesocosms to degrade CYN.

AB - Cyanobacterial blooms releasing harmful cyanotoxins, such as microcystin (MC) and cylindrospermopsin (CYN), are prominent threats to human and animal health. Constructed wetlands (CW) may be a nature-based solution for bioremediation of lake surface water containing cyanotoxins, due to its low-cost requirement of infrastructure and environmentally friendly operation. There is recent evidence that microcystin-LR (MC-LR) can efficiently be removed in CW microcosms where CYN degradation in CW is unknown. Likewise, the mechanistic background regarding cyanotoxins transformation in CW is not yet elucidated. In the present study, the objective was to compare MC-LR and CYN degradation efficiencies by two similar microbial communities obtained from CW mesocosms, by two different experiments setup: 1) in vitro batch experiment in serum bottles with an introduced CW community, and 2) degradation in CW mesocosms. In experiment 1) MC-LR and CYN were spiked at 100 µg L−1 and in experiment 2) 200 µg L−1 were spiked. Results showed that MC-LR was degraded to ≤1 µg L−1 within seven days in both experiments. However, with a markedly higher degradation rate constant in the CW mesocosms (0.18 day−1 and 0.75 day−1, respectively). No CYN removal was detected in the in vitro incubations, whereas around 50 % of the spiked CYN was removed in the CW mesocosms. The microbial community responded markedly to the cyanotoxin treatment, with the most prominent increase of bacteria affiliated with Methylophilaceae (order: Methylophilales, phylum: Proteobacteria). The results strongly indicate that CWs can develop an active microbial community capable of efficient removal of MC-LR and CYN. However, the CW operational conditions need to be optimized to achieve a full CYN degradation. To the best of our knowledge, this study is the first to report the ability of CW mesocosms to degrade CYN.

KW - Bacterial degradation

KW - Bioremediation

KW - Cyanotoxins

KW - Microbial community

KW - Treatment wetlands

UR - http://www.scopus.com/inward/record.url?scp=85178093218&partnerID=8YFLogxK

U2 - 10.1016/j.hal.2023.102549

DO - 10.1016/j.hal.2023.102549

M3 - Journal article

C2 - 38212082

AN - SCOPUS:85178093218

SN - 1568-9883

VL - 131

JO - Harmful Algae

JF - Harmful Algae

M1 - 102549

ER -