ECOTOXICITY OF TITANIUM DIOXIDE NANOPARTICLE TO CHLORELLA VULGARIS BEYERINCK (TREBOUXIOPHYCEAE, CHLOROPHYTA) UNDER LIMITED NITROGEN CONDITIONS IN VITRO
ECOTOXICITY OF TITANIUM DIOXIDE NANOPARTICLE TO CHLORELLA VULGARIS BEYERINCK (TREBOUXIOPHYCEAE, CHLOROPHYTA) UNDER LIMITED NITROGEN CONDITIONS IN VITRO
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Date
2016-04
Authors
DAUDA, Suleiman
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Abstract
The broad application of titanium dioxide nanoparticles in many consumer products has resulted
in the release of substantial amounts into aquatic system, which serve as the terminal sink for
nanomaterials. These titanium dioxide nanoparticles may induce some unexpected toxic effects to
aquatic organisms such as microalgae. This study was carried out to evaluate the toxicity of
limited nitrogen and titanium dioxide nanoparticles to the microalgae Chlorella vulgaris. The
nanoparticles were prepared in Organisation for Economic Cooperation and Development
(OECD) algal test medium and also the nitrogen concentration in the algal test medium was
adjusted to match limited environmental nitrogen level. The growth, biomass production,
biochemical composition (Carbohydrate and protein content), and antioxidant response
(Glutathione-s-transferase, peroxidase, and lipid peroxidation) of the algae were monitored over a
96h period. The results showed that limited nitrogen (2.8 × 10 -6 M) decrease growth, biomass
(dry weight, cell counts, chlorophyll content), carbohydrate content, and increase protein content,
antioxidant enzyme activity and lipid peroxidation (malondialdehyde content) in the alga.
Titanium dioxide nanoparicle treatments (0.2mg/L, 8mg/L, 16mg/L and 32mg/L) decrease
growth, biomass, carbohydrate content and increase glutathione-s-transferase activity. The
combination of limited nitrogen with titanium dioxide nanoparticle decrease growth, dry weight,
chlorophyll content, and carbohydrate content of the alga. This result suggests that limited
nitrogen and titanium dioxide nanoparticle treatments affects growth, biomass production,
biochemical composition, induces oxidative stress and also induces the oxidation of lipids while
titanium dioxide nanoparticle combined with limited nitrogen affect growth, biomass, and
carbohydrate content of Chlorella vulgaris under white fluorescent light.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF A MASTER OF SCIENCE DEGREE IN BOTANY.
Keywords
ECOTOXICITY,, TITANIUM DIOXIDE,, NANOPARTICLE,, CHLORELLA VULGARIS,, BEYERINCK,, TREBOUXIOPHYCEAE,, CHLOROPHYTA,