Biochemical markers and bioaccumulation capacity of cyanobacteria under fenitrothion stress: implications for aquatic bioremediation

Adaptation strategies of cyanobacteria under trace tetracycline exposure: A comparative study of toxigenic and non-toxigenic strains.

Trace antibiotics exert unclear ecological impacts on cyanobacteria, especially the differential responses between toxigenic and non-toxigenic strains. To address this, we established a paired-strain comparative framework exposing toxigenic Microcystis aeruginosa and non-toxigenic Synechocystis sp. to environmentally relevant tetracycline (0.2, 2, 20 μg/L) for 14 days. Results showed that TC induced hormetic growth in both strains, with final cell density increases of 2.47-9.79% (M. aeruginosa) and 4.98-8.59% (Synechocystis sp.) relative to controls, but exhibited divergent adaptation strategies. M. aeruginosa optimized photosystem efficiency, shifted to peroxidase (POD) and non‑enzymatic antioxidant defense, and down-regulated phosphate uptake. Synechocystis sp. expanded light‑harvesting complexes, co‑activated superoxide dismutase (SOD) and POD, and maintained elemental homeostasis. Transcriptomics revealed shared up-regulation of core metabolism and translation, providing a conserved molecular basis for the hormetic effect. Weighted gene co‑expression network analysis showed 11 modules in M. aeruginosa versus 5 modules in Synechocystis sp., indicating intrinsic molecular differences underlying the divergent adaptation strategies. Notably, TC promoted the synthesis and accumulation of microcystins (MCs) in M. aeruginosa but suppressed extracellular release, and the MC‑LR proportion decreased extracellularly but increased intracellularly. Thus, monitoring dissolved MCs alone may underestimate toxin risks and miss the risk of secondary contamination upon cell lysis. Overall, these findings reveal divergent adaptation strategies and shared regulatory mechanisms between toxigenic and non-toxigenic cyanobacteria, along with MCs metabolic remodeling under trace TC, offering new insights into bloom management under antibiotic pollution.

Mechanisms of toxicity and stress tolerance in aquatic plants under combined exposure to pharmaceuticals, personal care products, and eutrophication: A meta-analysis.

Given the increasing co-occurrence of pharmaceuticals and personal care products (PPCPs) and eutrophication in aquatic environments, it is crucial to understand PPCP-nutrient-plant interactions and their combined ecological impact. However, the literature regarding quantitative thresholds and metabolic trade-offs remain highly fragmented. In this meta-analysis, we compiled a dataset comprising 407 observations from 38 rigorously screened studies, covering various PPCP classes and floating, submerged, and emergent plant habitats. Remediation efficiency and physiological stress markers specifically enzymatic defense and oxidative damage were selected as informative endpoints for assessing plant responses to combined exposure. The combined stressors' phytotoxicity generally manifested as severe oxidative stress and metabolic exhaustion in submerged species, despite high apparent initial removal. However, the observed remediation phenotype was heavily influenced by experimental conditions, particularly exposure concentration, transitioning from a metabolic primer to an inhibitory stressor above a 10 mg/L threshold. Conversely, physiological stability and active removal efficiency were maintained in floating species and specific elite emergent candidates, particularly Vetiveria zizanioides, following exposure to co-contamination. Ultimately, this meta-analysis highlights the severe metabolic costs aquatic plants face in co-contaminated systems. We identified a critical toxicity tipping point at a 10 mg/L exposure concentration. Beyond this threshold, we observed a critical performance shift at a 10 mg/L exposure concentration. We hypothesize that beyond this threshold, plant defense systems are severely overwhelmed, and the observed removal of contaminants may transition from active biological degradation to passive physical sorption. These findings provide essential mechanistic insights into how combined chemical and nutrient stressors disrupt plant physiology, which is critical for understanding their broader ecological impact.

Integrated Physiological, Transcriptomic, and Metabolomic Analyses Reveal the Adaptive Response of Buchloe dactyloides to Polycyclic Aromatic Hydrocarbon Stress

The potential role of multiple pathways in the defense response of B. dactyloides roots against PAHs stress, including amino acid synthesis, flavonoid biosynthesis, galactose metabolism, glycerophospholipid metabolism, and other pathways, may contribute to antioxidative defense under PAHs stress.

Species-Specific Photosynthetic Inhibition and Lipid Remodeling in Freshwater Microalgae Exposed to Pb(II) Stress

Lead (Pb) is a persistent environmental contaminant that poses a significant risk to aquatic primary producers by disrupting photosynthesis, cellular metabolism, and physiological homeostasis. This study investigated the physiological and biochemical responses of two freshwater green microalgae, Mucidosphaerium pulchellum and Micractinium pusillum, exposed to Pb(II) concentrations ranging from 0 to 30 mg L−1. Species-specific responses were evaluated through growth kinetics, chlorophyll fluorescence, lipid accumulation, and fatty acid profiling to elucidate mechanisms underlying Pb stress tolerance. Pb(II) exposure resulted in concentration-dependent inhibition of growth and photosynthetic activity in both species, with marked reductions in quantum yield and increases in photosynthetic inhibition at the highest exposure concentration (30 m L−1), reaching approximately 95% in M. pulchellum and 93% in M. pusillum. Lipid metabolism exhibited distinct species-specific responses: M. pulchellum showed a progressive decline in total lipid content, whereas M. pusillum exhibited enhanced lipid accumulation under moderate Pb exposure followed by depletion under severe stress. Fatty acid analysis revealed significant membrane lipid remodeling, characterized primarily by reductions in polyunsaturated fatty acids, particularly α-linolenic acid (C18:3), with stronger alterations observed in M. pulchellum. These findings demonstrate that Pb toxicity involves interconnected effects on photosynthetic efficiency, carbon allocation, and membrane lipid composition, with species-specific differences in physiological resilience. The combined application of chlorophyll fluorescence and lipid-related biomarkers provides a sensitive approach for assessing heavy-metal stress responses and improving understanding of Pb tolerance mechanisms in freshwater microalgae. These findings provide a physiological basis for the development of sustainable biomonitoring approaches for freshwater ecosystems.

Herbicide-Induced Physiological Changes in Myriophyllum verticillatum: Linuron and Nicosulfuron Exposure and Implications for Aquatic Ecosystem Health

Harnessing salinity induced adaptive potential of extracellular polymeric substances producing rice-field cyanobacterium Neowestiellopsis sp. VKB03: a physiochemical, morphological, and biomass characterization