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Structure and physiological activity of cyanobacterial communities in a freshwater lake: a three-year study using 16S rRNA gene sequencing analysis
Citation:
SANTO-DOMINGO, J. W., M. Bagley, A. Banerji, J. Shoemaker, AND H. J. ALLEN. Structure and physiological activity of cyanobacterial communities in a freshwater lake: a three-year study using 16S rRNA gene sequencing analysis. North American Lake Management Society 38th International Meeting, Cincinnati,OH, October 30 - November 02, 2018.
Impact/Purpose:
We identified the types of cyanobacteria in a freshwater reservoir, including species that are known to potentially produce cyanotoxins. While cyanobacteria are common phototrophic inhabitants of natural water systems, they can also pose significant hazard to humans and other biota via toxic by-products known as cyanotoxins. Standard cyanobacterial monitoring relies on time consuming microscopic methods that may not easily discriminate between different groups and that do not provide information on their physiological status. To circumvent these issues, we used next-generation sequencing to generate 16S rRNA gene metabarcoding libraries for water samples collected from five different sites within a multipurpose freshwater reservoir. Samples were collected over three consecutive years from May to September and both DNA and RNA were used to determine the diversity, relative abundance and physiological activity of the cyanobacteria identified. Analysis of nearly 30 million sequences revealed the presence of 16 different genera within the lake. Of the cyanobacteria known to produce cyanotoxins, Dolichospermum, Planktothrix, Microcystis, Cylindrospermopsis, Aphanizomenon, and Pseudanabaena were the most abundant (in that order). Temporal changes were noted in both relative abundance and activity, with Dolichospermum showing the highest levels early during the monitoring period. Sizeable increases in the other aforementioned genera followed after mid-June. Parallel increases in Microcystis abundance and microcystin levels were noted, implicating the latter cyanobacterial group as primarily responsible for toxin production. In summary, we showed that metabarcoding is a robust tool for assessing the diversity of cyanobacteria in natural systems. The results provide the foundation for understanding the population dynamics of cyanobacteria in relation to toxic cyanobacterial blooms.
Description:
While cyanobacteria are common phototrophic inhabitants of natural water systems, they can also pose significant hazard to humans and other biota via toxic by-products known as cyanotoxins. Standard cyanobacterial monitoring relies on time consuming microscopic methods that may not easily discriminate between different groups and that do not provide information on their physiological status. To circumvent these issues, we used next-generation sequencing to generate 16S rRNA gene metabarcoding libraries for water samples collected from five different sites within a multipurpose freshwater reservoir. Samples were collected over three consecutive years from May to September and both DNA and RNA were used to determine the diversity, relative abundance and physiological activity of the cyanobacteria identified. Analysis of nearly 30 million sequences revealed the presence of 16 different genera within the lake. Of the cyanobacteria known to produce cyanotoxins, Dolichospermum, Planktothrix, Microcystis, Cylindrospermopsis, Aphanizomenon, and Pseudanabaena were the most abundant (in that order). Temporal changes were noted in both relative abundance and activity, with Dolichospermum showing the highest levels early during the monitoring period. Sizeable increases in the other aforementioned genera followed after mid-June. Parallel increases in Microcystis abundance and microcystin levels were noted, implicating the latter cyanobacterial group as primarily responsible for toxin production. In summary, we showed that metabarcoding is a robust tool for assessing the diversity of cyanobacteria in natural systems. The results provide the foundation for understanding the population dynamics of cyanobacteria in relation to toxic cyanobacterial blooms.