رسائل دكتوراة
English
2023
Using of Immobolized Chlorella vulgaris for Reduction of Amoxicillin and Potasium dichromate against toxicity on two Species of Bivalve
جاسم محمد سلمان, زهراء حسين عبيد علي, نهى فالح كاظم
كلية العلوم-جامعة بابل · العراق
Aquatic pollution with pharmaceutical compounds is considered one of the most significant environmental challenges worldwide, due to urbanization, industrial waste, and the resulting potential risks to human health and aquatic ecosystems. In this study, two types of pharmaceutical compounds were used: the antibiotic amoxicillin (AMX) and the disinfectant potassium dichromate (K₂Cr₂O₇) to induce toxicity in two selected species of bivalves, Pseudodontopsis euphraticus and Corbicula fluminea, which were collected from a site on the Euphrates River in the Al-Hindiya District, central Iraq. Immobilized algae (Chlorella vulgaris) were applied to reduce the toxicity of the mentioned pollutants.
Several environmental variables of the riverbank were measured when collecting bivalves, including water temperature (12.4–22.5 °C), air temperature (26.2–33.4 °C), pH (7.3–8.34), electrical conductivity (1058–1130 μS/cm), salinity (0.55–0.73 ppt), dissolved oxygen (5.9–7.80 mg/L), biological oxygen demand (1.7–3.35 mg/L), and total dissolved solids (430.3–694 mg/L).
The lethal concentration 50 (LC₅₀) of AMX was measured at different concentrations (100, 200, 300 mg/L) in a total of 144 clams (P. euphraticus and C. fluminea), and the LC₅₀ values within 96 hours were 410.55 and 441.15 mg/L, respectively. While the LC₅₀ values for 96 hours were 73.96 and 76.73 mg/L when using potassium dichromate at concentrations of 20, 30, 50, 100, and 150 mg/L in a total of 216 clams (P. euphraticus and C. fluminea), respectively.
Selected bivalves showed a variety of behavioral changes after exposure to pharmaceutical substances, including tightly closing their valves for longer periods than usual, and occasionally extending their feet and siphons while remaining relatively motionless at high concentrations. Other behaviors included irregular swimming bursts, flattening, mucus secretion, and inactivity.
Biochemical indicators of both bivalve species were studied after exposure to AMX in the absence of immobilized algae (C. vulgaris), and the results were as follows: Reactive oxygen species (ROS) levels were 12.99–22.52 μg/mg for P. euphraticus and 30.79–42.86 μg/mg for C. fluminea. For P. euphraticus, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) values were 20.79–33.33 U/mL, 25.44–30.53 KU/L, and 5.70–8.36 U/L, respectively. For C. fluminea, the corresponding values were 35.49–50.03 U/mL, 42.51–51.78 KU/L, and 16.41–21.12 U/L, respectively. Glutathione (GSH) values were 7.55–10.37 μg/g and 4.25–8.03 μg/g, respectively, while ascorbic acid (AA) ranged between 13.41–14.48 μM and 42.92–76.79 μM. Total protein (TP) values were 9.65–11.14 mg/g and 35.52–19.57 mg/g, while malondialdehyde (MDA) values were 17.69–42.43 μmol/L and 9.33–17.21 μmol/L, respectively.
When immobilized C. vulgaris was applied in the presence of AMX, biochemical markers showed reduced toxicity: ROS were 8.89–16.73 μg/mg and 21.33–35.49 μg/mg, SOD 12.72–21.62 U/mL and 21.46–35.49 U/mL, CAT 17.56–25.15 KU/L and 22.16–35.33 KU/L, GPX 5.02–9.58 U/L and 14.16–19.28 U/L, GSH 2.83–6.27 μg/g and 6.54–9.46 μg/g, AA 13.41–14.48 μM and 38.11–59.80 μM, TP 14.25–15.60 mg/g and 39.23–41.41 mg/g, and MDA 6.77–22.72 μmol/L and 11.60–23.97 μmol/L for P. euphraticus and C. fluminea, respectively.
The same experimental conditions were applied in the absence of C. vulgaris by exposing the bivalves to K₂Cr₂O₇ at 20, 30, and 50 mg/L. The biochemical markers were: ROS 37.50–51.05 μg/mg and 37.89–63.66 μg/mg, SOD 33.40–28.36 U/mL and 54.04–35.96 U/mL, CAT 25.76–27.16 KU/L and 27.19–46.74 KU/L, GPX 4.35–6.34 U/L and 10.99–43.35 U/L, GSH 8.57–16.37 μg/g and 12.79–36.86 μg/g, AA 20.37–26.94 μM and 35.3–50.37 μM, TP 10.86–12.79 mg/g and 18.43–39.11 mg/g, and MDA 29.01–59.88 μg/L and 12.68–23.22 μg/L, respectively.
When immobilized C. vulgaris was added, the biochemical markers were slightly improved: ROS 33.88–42.06 μg/mg and 41.0–51.0 μg/mg, SOD 27.19–46.74 U/mL and 23.36–31.4 U/mL, CAT 26.88–40.32 KU/L and 24.55–48.99 KU/L, GPX 7.34–3.87 U/L and 9.37–37.99 U/L, GSH 9.7–22.47 μg/g and 7.58–30.26 μg/g, AA 24.83–27.94 μM and 23.67–38.89 μM, TP 10.93–13.56 mg/g and 35.69–20.44 mg/g, and MDA 9.81–11.44 μmol/L and 23.06–47.92 μmol/L, respectively.
Concentrations of 50 g/L K₂Cr₂O₇ and 300 g/L AMX were mostly responsible for the high observed effects. After long-term exposure, P. euphraticus suffered a variety of histological changes including infiltration of cells and blood cells, cell degeneration, expansion of lymphatic spaces between tubules, necrosis of digestive gland cells, and narrowing of the tubular lumen. Histological changes in the anterior gills included fusion of cilia, cell hyperplasia, blood cell infiltration, necrosis, and rupture of epithelial cells.
Regarding C. fluminea, changes in the digestive glands included atrophy and proliferation of digestive tubes, connective tissue infiltration, necrosis of digestive gland cells, narrowing of the tubular lumen, and necrosis of lymph nodes. Histological changes in the gills included cell infiltration, epithelial necrosis, rupture of the epithelial layer, and cilia fusion.