Toolbox for the sampling and monitoring of benthic cyanobacteria

Virginie Gaget; Peter Hobson; Angela Keulen; Kelly Newton; Paul Monis; Andrew R Humpage; Laura S Weyrich; Justin D Brookes

doi:10.1016/j.watres.2019.115222

Toolbox for the sampling and monitoring of benthic cyanobacteria

Water Res. 2020 Feb 1:169:115222. doi: 10.1016/j.watres.2019.115222. Epub 2019 Oct 23.

Authors

Virginie Gaget¹, Peter Hobson², Angela Keulen³, Kelly Newton², Paul Monis⁴, Andrew R Humpage², Laura S Weyrich⁵, Justin D Brookes³

Affiliations

¹ Water Research Centre, Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of Adelaide, South Australia, 5005, Australia. Electronic address: virginie.gaget@adelaide.edu.au.
² Australian Water Quality Centre, South Australia Water Corporation, Adelaide, South Australia, 5000, Australia.
³ Water Research Centre, Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of Adelaide, South Australia, 5005, Australia.
⁴ Water Research Centre, Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of Adelaide, South Australia, 5005, Australia; Australian Water Quality Centre, South Australia Water Corporation, Adelaide, South Australia, 5000, Australia.
⁵ Australian Centre for Ancient DNA, Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of Adelaide, South Australia, 5005, Australia.

PMID: 31675609
DOI: 10.1016/j.watres.2019.115222

Abstract

Benthic cyanobacteria are a nuisance because they produce highly potent toxins and taste and odour compounds. Despite this, benthic cyanobacteria remain far less studied than their planktonic counterparts. For example, little is known about their growth or the seasonality of their secondary metabolite production. Moreover, sampling and monitoring techniques commonly used for the survey of planktonic species are not necessarily applicable to benthic forms. This study aimed to develop and validate a new sampling device for the routine monitoring of benthic mats. Molecular monitoring techniques were established and validated on environmental samples collected in a South Australian reservoir (SA-L2). A total of eight qPCR assays were applied to samples in order to track seasonal variations in cyanobacteria concentrations and associated secondary metabolite production. Next Generation Sequencing was utilised to conduct a microbial community composition analysis and to select the most appropriate substrate material for the sampling of benthic cyanobacteria. The concentration of the secondary metabolites geosmin and 2-methyl-isoborneol were quantified using High-Performance Liquid Chromatography, and concentrations of key nutrients (N, P) were quantified in water samples. The sampling device designed proved efficient and easy to use in the field. The qPCR assay designed for the amplification of the cyanobacterial MIB synthase had a high efficiency with a minimum limit of quantification of 4 cell-equivalents per reaction and identified a potential source of MIB in SA-L2 Reservoir. The peak season for benthic growth and secondary metabolite production was observed in spring. Proportionally, 35% of the variability in water geosmin concentrations can be explained by benthic actinobacterial and cyanobacterial activity, showing that freshwater benthic mats represent a significant source of taste and odour compounds.

Keywords: Benthic cyanobacteria; Monitoring; Next generation sequencing; Sampling; Taste and odour compounds; Toxins.

MeSH terms

Australia
Cyanobacteria*
Fresh Water
Odorants
Taste