Di-(2-ethylhexyl) phthalate induced the growth inhibition and oxidative damage in the microalga Chlorella vulgaris

Integrated proteome and pangenome analysis revealed the variation of microalga Isochrysis galbana and associated bacterial community to 2,6-Di-tert-butyl-p-cresol (BHT) stress

The phenolic antioxidant 2,6-Di-tert-butyl-p-cresol (BHT) has been detected in various environments and is considered a potential threat to aquatic organisms. Algal-bacterial interactions are crucial for maintaining ecosystem balance and elemental cycling, but their response to BHT remains to be investigated. This study analyzed the physiological and biochemical responses of the microalga Isochrysis galbana and the changes of associated bacterial communities under different concentrations of BHT stress. Results showed that the biomass of I. galbana exhibited a decreasing trend with increasing BHT concentrations up to 40 mg/L. The reduction in chlorophyll, carotenoid, and soluble protein content of microalgal cells was also observed under BHT stress. The production of malondialdehyde and the activities of superoxide dismutase, peroxidase, and catalase were further determined. Scanning electron microscopy analysis revealed that BHT caused surface rupture of the algal cells and loss of intracellular nutrients. Proteomic analysis demonstrated the upregulation of photosynthesis and citric acid cycle pathways as a response to BHT stress. Additionally, BHT significantly increased the relative abundance of specific bacteria in the phycosphere, including Marivita, Halomonas, Marinobacter, and Alteromonas. Further experiments confirmed that these bacteria had the ability to utilize BHT as the sole carbon resource for growth, and genes related to the degradation of phenolic compounds were detected through pangenome analysis.

Transient effect of bisphenol A (BPA) and di-(2-ethylhexyl) phthalate (DEHP) on the cosmopolitan marine diatom Chaetoceros decipiens-lorenzianus

Incubation under controlled laboratory conditions were performed to assess the toxic effects of two plastic derived chemicals, bisphenol A (BPA) and di-(2-ethylhexyl) phthalate (DEHP), on the growth, photosynthetic efficiency and photosynthetic activity of the cosmopolitan diatom Chaetoceros decipiens-lorenzianus. Non-axenic diatom cells were exposed to concentrations of BPA and DEHP (separately and in mixture), mimicking concentrations observed in contaminated marine ecosystems, for seven days. Upon short-term exposure (i.e., during the first 48 h), BPA and DEHP induced a slight but significant stimulation of biomass and photosynthetic activity relative to the control, whereas, no significant impact was observed on the photosynthetic efficiency. Nevertheless, this pattern was transient. The stimulation was followed by a return to control conditions for all treatments at the end of incubation. These results showed that the cosmopolitan diatom Chaetoceros was not impacted by representative in situ concentrations of plastic derivatives, thus confirming its ability to thrive in coastal anthropogenic environments.

Ecotoxico Linking of Phthalates and Flame-Retardant Combustion Byproducts with Coral Solar Bleaching

Persian Gulf coral reefs are unique biota communities in the global sunbelts in being able to survive in multiple stressful fields during summertime (>36 °C). Despite the high-growth emerging health-hazard microplastic additive type of contaminants, its biological interactions with coral-algal symbiosis and/or its synergistic effects linked to solar-bleaching events remain unknown. This study investigated the bioaccumulation patterns of polybrominated diphenyl ether (PBDE) and phthalate ester (PAE) pollutants in six genera of living/bleached corals in Larak Island, Persian Gulf, and their ambient abiotic matrixes. Results showed that the levels of ∑₁₈PBDEs and ∑₁₃PAEs in abiotic matrixes followed the order of SPMs > surface sediments > seawater, and the cnidarian POP-uptake patterns (soft corals > hard corals) were as follows: coral mucus (138.49 ± 59.98 and 71.57 ± 47.39 ng g^-1 dw) > zooxanthellae (82.05 ± 28.27 and 20.14 ± 12.65 ng g^-1 dw) ≥ coral tissue (66.26 ± 21.42 and 34.97 ± 26.10 ng g^-1 dw) > bleached corals (45.19 ± 8.73 and 13.83 ± 7.05 ng g^-1 dw) > coral skeleton (35.66 ± 9.58 and 6.47 ± 6.47 ng g^-1 dw, respectively). Overall, findings suggest that mucus checking is a key^/facile diagnostic approach for fast detection of POP bioaccumulation (PB) in tropical corals. Although studied corals exhibited no consensus concerning hazardous levels of PB (log BSAF < 3.7), our bleaching evidence showed soft corals as the ultimate "summer winners" due to their flexibility/recovering ability.

Inhibition Properties of Arylsulfatase and β-Glucuronidase by Hydrogen Peroxide, Hypochlorite, and Peracetic Acid

Arylsulfatase and β-glucuronidase are two important enzymes in humans, which play an important role in the dynamic equilibrium of steroidal estrogens. This work probably for the first time reported that hydrogen peroxide (H₂O₂), hypochlorite, and peracetic acid (PAA) could effectively inhibit the activities of arylsulfatase and/or β-glucuronidase. The 50% of inhibitions (IC₅₀) of H₂O₂, hypochlorite, and PAA on arylsulfatase were found to be 142.90 ± 9.00, 91.83 ± 10.01, and 43.46 ± 2.92 μM, respectively. The corresponding IC₅₀ values of hypochlorite and PAA on β-glucuronidase were 704.90 ± 41.40 and 23.26 ± 0.82 μM, whereas H₂O₂ showed no inhibition on β-glucuronidase. The inhibitions of arylsulfatase and/or β-glucuronidase by these three chemicals were pH-dependent. It was further revealed that the inhibitions of hypochlorite on both arylsulfatase and β-glucuronidase were irreversible. On the contrary, the inhibitions by H₂O₂ and PAA were reversible. In addition, the inhibition by H₂O₂ was competitive and that by PAA was noncompetitive. In general, H₂O₂ and hypochlorite can be endogenously produced in humans, which suggested that the two compounds are potential endocrine disruption compounds (EDCs) as they can cause endocrine disruption via the inhibition of arylsulfatase and β-glucuronidase. This work further indicated that any agent that can induce the production of H₂O₂ or hypochlorite in humans is a potential EDC, which explains why some EDCs with very weak or no estrogenic potency can cause endocrine disruption, which is confirmed in epidemiological studies.