Laboratory-Simulated Inhibitory Effects of the Floating-Bed Plants on Microcystis aeruginosa and Their Microbial Communities' Responses to Microcystins

Shuwen Zhang ^1,2, Yuanpu Sha ^1,2, Yuanyuan Tang ^1,2

⁰College of Fisheries, Henan Normal University, Jianshe Road, Xinxiang 453007, China.

Microorganisms +

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October 26, 2024

View abstract on PubMed

Summary

Floating plants like water hyacinth and water lettuce effectively inhibit toxic Microcystis aeruginosa growth and remove microcystins. These plants also show antioxidant responses and host beneficial bacteria for water remediation.

Area Of Science

Environmental Science
Aquatic Botany
Microbiology

Background

Harmful algal blooms (HABs) caused by toxic Microcystis aeruginosa pose significant threats to aquatic ecosystems.
Microcystins (MCs) are potent toxins produced by M. aeruginosa, impacting water quality and public health.
Floating aquatic plants are increasingly explored for bioremediation due to their potential to absorb nutrients and contaminants.

Purpose Of The Study

To evaluate the efficacy of three common floating plants—Eichhornia crassipes, Pistia stratiotes, and Ipomoea aquatica—in inhibiting M. aeruginosa growth.
To assess the capacity of these plants to remove microcystins from contaminated water.
To investigate the plants' physiological responses and associated microbial communities during microcystin removal.

Main Methods

Controlled experiments were conducted using floating plants to treat water inoculated with M. aeruginosa.
Microcystin concentrations (intracellular and extracellular) were measured using established analytical techniques.
Plant physiological responses, including antioxidant enzyme activities (CAT, GSH-PX, SOD) and malondialdehyde (MDA) levels, were analyzed.
Root-associated microbial communities were characterized using 16S rRNA gene sequencing.

Main Results

All three floating plants significantly inhibited M. aeruginosa growth and effectively removed microcystins.
Eichhornia crassipes and Pistia stratiotes demonstrated superior efficacy, achieving up to 100% removal of intracellular microcystins.
Plants exhibited enhanced antioxidant responses, with increased levels of CAT, GSH-PX, SOD, and MDA, indicating stress tolerance.
Root microbial communities were dominated by Proteobacteria, Bacteroidota, Myxococcota, Verrucomicrobiota, and Actinobacteriota.
MC-degrading bacteria, including Sphingomonas, Acinetobacter, Novosphingobium, and Pseudomonas, were identified.

Conclusions

Floating plants, particularly E. crassipes and P. stratiotes, are effective biological tools for controlling M. aeruginosa blooms and mitigating microcystin contamination.
The plants' antioxidant systems play a role in managing microcystin toxicity.
The associated root microbiome, including specific MC-degrading genera, contributes to the overall bioremediation process.
These findings provide crucial data for developing integrated strategies for managing eutrophic water bodies and removing microcystins.

Keywords:

MCs-degrading bacteria algal inhibition antioxidant system eutrophic water bodies inter-root microorganisms