Date of Award

Spring 5-2024

Degree Type

Thesis

Degree Name

MS Biology

Department

Biology

Advisor

Tinchun Chu, PhD

Committee Member

Jane L. Ko, PhD

Committee Member

Jessica A. Cottrell, PhD

Keywords

cyanobacteria, anatoxin-a, cyanotoxin, FeCl3, metal stress, Anabaena

Abstract

Anabaena flos-aquae, a freshwater cyanobacterium, is a common contributor to cyanobacterial harmful algal blooms (CHABs). Under environmental stressors such as nutrient imbalances, temperature changes, or exposure to emerging contaminants like heavy metals, this microbe can release anatoxin-a, a potent neurotoxin. This raises concerns about the safety of drinking water contaminated with toxin-producing cyanobacteria. In this study, four flasks of Anabaena flos-aquae were exposed to varying concentrations of iron chloride (FeCl3) to evaluate its stress response and survivability. The optical density (OD) of each sample was monitored periodically over three weeks, and the samples were stored for further analysis. An enzyme-linked immunosorbent assay (ELISA) was performed to measure total anatoxin-a levels in each sample. Results showed that the control group without FeCl3 and the cells exposed to 50 mg/L FeCl3 had higher OD readings and overall increased growth. In contrast, cells exposed to 100 and 125 mg/L FeCl3 experienced a decline in cell numbers. ELISA results revealed that cells exposed to 100 mg/L FeCl3 released the highest level of anatoxin-a among all groups, reaching up to 1.096 µg/L during the monitoring period. Furthermore, QIAGEN’s Ingenuity Pathway Analysis (IPA) tool was used to perform an in-silico analysis of the effects of Anatoxin-a on human health. Lastly, RNA-sequencing (RNA-seq) will be conducted to explore the transcriptomic responses to iron stress, and the results will be incorporated into IPA to better understand the relationship between metal stress and toxin production.

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