Učinak glukoze na oksidacijski stres i fotosintezu u mikroalgi Chlorella vulgaris izloženoj nanočesticama srebra

master's thesis

• Title (english): The effect of glucose on oxidative stress and photosynthesis in the freshwater microalga Chlorella vulgaris exposed to silver nanoparticles
• Author: Kristina Gilman
• Mentor: Petra Peharec Štefanić (mentor)
• Mentor: Bruno Komazec (komentor)
• Committee member: Petra Peharec Štefanić (predsjednik povjerenstva)
• Committee member: Tomislav Ivanković (član povjerenstva)
• Committee member: Biljana Balen (član povjerenstva)
• Committee member: Sunčica Bosak (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2025-02-20, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Nanočestice srebra (AgNP) se zbog svojih specifičnih kemijskih i fizikalnih svojstava danas
sve više koriste u raznim granama industrije. Zbog svoje toksičnosti i ispuštanja u otpadne vode
predstavljaju opasnost za vodene ekosustave. Mikroalga Chlorella vulgaris se zbog brzog rasta
i prilagodne vanjskim uvjetima koristi kao modelni organizam u mnogim istraživanjima.
Fitotoksičan utjecaj AgNP na mikroalgu je poznat, a s obzirom da ova mikroalga može prijeći
s autotrofnog na miksotrofni način života, u ovom radu istražila sam kakav utjecaj ima glukoza,
kao dodatan izvor energije, na fitotoksičnost AgNP-citrata, prateći parametre oksidacijskog
stresa i fotosinteze. Alge sam uzgajala na hranjivim podlogama s dodatkom i bez dodatka
glukoze i tretirala ih s koncentracijom AgNP-citrat koja omogućuje preživljenje 60% stanica.
U svim tretmanima s glukozom došlo je do smanjenja koncentracije reaktivnih oblika kisika i
lipidne peroksidacije te povećanja aktivnosti antioksidacijskih enzima katalaze, askorbat
peroksidaze i pirogalol peroksidaze u odnosu na tretmane bez glukoze. U tretiranim algama
uzgajanim na podlogama s dodatkom glukoze izmjerena je viša stopa fotosinteze, viši
maksimalni kvantni prinos fotosustava II, veći indeks učinkovitosti fotosinteze te niža aktivnost
klorofila a i b te karotenoida u usporedbi s tretmanom bez glukoze. Svi izmjereni parametri
ukazuju na ublažavajući učinak glukoze na fitotoksičnost AgNP-citrata.

Abstract (english)

Silver nanoparticles (AgNPs) are increasingly used in various industries due to their specific
chemical and physical properties. However, their toxicity and release into wastewater pose a
threat to aquatic ecosystems. Microalga Chlorella vulgaris is commonly used as a model
organism in research due to its rapid growth and adaptability to external conditions. The
phytotoxic effects of AgNPs on this microalga are well known. Since C. vulgaris can switch
from an autotrophic to a mixotrophic mode of life, this study investigated the influence of
glucose, as an additional energy source, on the phytotoxicity of AgNP-citrate by monitoring
oxidative stress and photosynthesis parameters.The algae were cultivated in nutrient media with
and without glucose supplementation and treated with a concentration of AgNP-citrate that
allows 60% cell survival. In all treatments with glucose, there was a decrease in reactive oxygen
species concentration and lipid peroxidation, as well as an increase in the activity of antioxidant
enzymes, including catalase, ascorbate peroxidase, and pyrogallol peroxidase, compared to
treatments without glucose. Algae grown in glucose-supplemented media showed a higher
photosynthetic rate, a higher maximum quantum yield of photosystem II, a greater
photosynthetic efficiency index, and lower chlorophyll a, chlorophyll b, and carotenoid activity
compared to the treatment without glucose. All measured parameters indicate a mitigating
effect of glucose on the phytotoxicity of AgNP-citrate.

• Keywords: slatkovodna alga; miksotrofija; reaktivni oblici kisika; antioksidacijski enzimi; fotosintetski pigmenti; fotosustav II
• Keywords (english): freshwater alga; mixotrophy; reactive oxygen species; antioxidant enzymes; photosynthetic pigments; photosystem II
• Language: croatian
• URN:NBN: urn:nbn:hr:217:671282
• Study programme: Title: Experimental Biology-University graduate programme; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra eksperimentalne biologije (sveučilišni/a magistar/magistra eksperimentalne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2025-02-28 13:11:53