Date of Award


Degree Type


Degree Name

MS Microbiology




Tinchun Chu, Ph.D.

Committee Member

Jane L. Ko, Ph.D.

Committee Member

Gregory R. Wiedman, Ph.D.


Cyanobacteria, Nickel, Anabaena, Algal Bloom, Stress Response, Metal


Heavy metal contamination due to anthropogenic activities has steadily been on the rise over the past few decades. Cyanobacteria can thrive in water bodies that have been contaminated by heavy metal runoffs and are able to tolerate heavy metal stress even in relatively high concentrations. Cyanobacterial species can secrete toxins which can prove harmful to humans and life stock. Due to their high adaptation to heavy metal stress, understanding the potential mechanism behind their response may lead to solutions in curbing excessive cyanobacterial growth especially in water bodies that serves as sources of drinking water. Anabaena spp. is a genus of filamentous cyanobacteria capable of forming cyanobacterial harmful algal blooms (CHABs) in eutrophic water bodies. Toxins secreted during these blooming events can be irritating to the skin and deleterious to health when ingested by humans and animals.

To understand the potential mechanism behind the stress response, Anabaena cylindrica cultures were exposed to increasing concentrations of the aqueous nickel chloride (0, 1, 2, 4 mg/L). Culture flasks were kept at room temperature under constant cool fluorescent white light on an incubator shaker at 100 rpm. Cell growth and morphology was monitored daily with cell microscopy, turbidity, and cell concentration over a period of one month. Flow cytometry was carried out to determine changes in pigmentation due to metal stress.

QIAGEN Ingenuity Pathway Analysis (IPA) was used to predict the impact of cyanotoxins (anatoxin-a and microcystins) on human health since cyanobacteria and human have some ubiquitous genes such as metallothionein. Cyanotoxins have been linked to neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS).

Available for download on Wednesday, May 20, 2026