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University of Fort Hare (2013)

Heavy metal content absorption and medicinal potential of Egeria densa (Planch.) Casp.

Mgobozi, Vuyokazi

Titre : Heavy metal content absorption and medicinal potential of Egeria densa (Planch.) Casp.

Auteur : Mgobozi, Vuyokazi

Université de soutenance : University of Fort Hare

Grade  : M.Sc (Botany) 2013

Résumé
The contamination of heavy metals in the environment is a looming concern worldwide. Egeria densa (Planch) (Submerged aquatic plant) from two ponds : Site A with co-ordinates (32º 48’22.04”S ; 26°48’58.79” E) and Site B with co-ordinates (32°48’33.25”S ; 26°48’33.25”S) in Alice (Eastern Cape) was evaluated for its ability to absorb heavy metals, phytochemical constituents, antimicrobial activity and ultra-structure using standard analytic procedures. Cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), and zinc (Zn) were measured in water, sediments and plant. The concentrations of these metal elements were determined with use of Inductively Coupled Plasma- Optical Emission Spectrometry (ICP-OES). In sediments, the heavy metals (mg/kg) decreased in the order of their average concentration as follows : Fe (40.320) > Zn (1.259) > Pb (0.564) > Mn (0.186) > Cu (0.037) in Pond 1 whereas in Pond 2 Fe (61.527) > Cd (0.999) > Mn (0.648) > Pb (0.586) > Zn (0.156) > Cu (0.045). The highest concentration of Fe was detected in both sites and Cu being the least. The concentrations of the metals in the plants sample (from Pond 1) were found in order of Mn > Pb > Cu > Fe whereas cadmium and zinc were not detected, while the concentration in Pond 2 decreases in order of Zn > Mn > Pb > Cd > Fe > Cu. In the water samples, concentrations of heavy metals (mg/L) decreased in the order of their average concentrations as follows : Pb (35.36) > Fe (3.07) > Mn (0.238) > Cu (0.104), both cadmium and zinc were below the limit of detection in Pond 1, whereas in Pond 2 the concentrations decreased as follows : Pb (13.033) >Fe (1.69) > Cu (0.270) > Mn (0.248) > Cd (0.004) and Zinc was not detected. Phytochemical analyses of the plant extracts revealed the presence of phenols, flavonoids, proanthocyanidin, flavonols, saponins, alkaloid and tannins in all the extracts (water, acetone and n-hexane). Both acetone and water extracts, showed high concentration of proanthocyanidin, while tannin was the lowest in acetone extract. Antimicrobial evaluation using, Gram positive (Staphylococcus aureus, Bacillus pumilus, Bacillus cereus, Streptococcus pyogenes, Enterococcus faecalis) and Gram negative (Klebsiella pneumonia, Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Serratia marcescens) bacteria showed negative results for all the strain, except Streptococcus pyogenes which was inhibited at MIC of 0.1 mg/ml. Scanning electron microscopy (SEM) of ultra-structure of Egeria densa, showed that certain bacteria attached to the leaf, However more work has to be done on E. densa to verify the mechanism by which it accumulates heavy metals. The study shows that E. densa has a potential of accumulating heavy metals especial Manganese in plant.

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Page publiée le 10 janvier 2016, mise à jour le 8 juin 2018