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Natural non-protein amino acids in diverse ecosystems

University of British Columbia

Cyanobacteria form large blooms and produce toxins which bioaccumulate in common foods. Exposure to cyanobacterial toxins, including the non-protein amino acid β-N-methylamino-L-alanine (BMAA), is linked to increased risk of neurodegenerative disease. Three isomers of BMAA: 2,4-diaminobutyric acid (DAB), N-(2-aminoethyl)glycine (AEG) and β-aminomethyl-L-alanine (BAMA) are also routinely measured. My overall objective was to develop research methods and approaches for studies of non-protein amino acids in diverse ecosystems. My specific objectives were: (a) to systematically review analytical methods for BMAA; (b) to develop a method to isolate a cyanobacterial protein for use in a field-deployable BMAA biosensor; (c) to quantify BMAA and its isomers in cyanobacteria from Lake Winnipeg and Pavilion Lake; (e) to determine the persistence and quantity of BMAA in the traditional cyanobacterial foods of the indigenous peoples of Peru and Chile; and (f) to determine whether these traditional cyanobacterial foods provide nutritional benefits. The largest discrepancy between BMAA analytical methods arose from the analysis of cyanobacterial matrices suggesting that methods must be fully validated. I also developed a BMAA-bound affinity chromatography resin to isolate BMAA-binding cyanobacterial proteins that can be used in a field-deployable biosensor. In Lake Winnipeg, BMAA and BAMA were found in highest concentration in the north basin, the lowest nitrogen region of the lake while AEG and DAB were found in the more nitrogen-rich zone. Analysis of microbialites collected from Pavilion Lake in British Columbia revealed that AEG, DAB and BAMA were highest in the shallow microbialites while BMAA was highest in deeper collections. In studies of non-protein amino acids, minerals, proteins and other nutrients in traditional cyanobacterial foods from Peru and Chile, I found BMAA and AEG in lower concentration than DAB and BAMA in cyanobacterial foods. Environmental toxins including lead, mercury and arsenic were also detected in traditional Andean foods. Overall, my studies show that cyanobacteria produce BMAA and its isomers in diverse ecosystems and food webs. A better understanding of these non-protein amino acids will provide insight into environmental factors that have shaped the evolution of life on early earth and recommendations for water management strategies to mitigate risks to human health.

Text

2020-07-13

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/75145

Chemistry

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/