title: The effect of cyanobacterial biomass enrichment by centrifugation and GF/C filtration on subsequent microcystin measurement.
abstract: Microcystins are cyclic peptides produced by multiple cyanobacterial genera. After accumulation in the liver of animals they inhibit eukaryotic serine/threonine protein phosphatases, causing liver disease or death. Accurate detection/quantification of microcystins is essential to ensure safe water resources and to enable research on this toxin. Previous methodological comparisons have focused on detection and extraction techniques, but have not investigated the commonly used biomass enrichment steps. These enrichment steps could modulate toxin production as recent studies have demonstrated that high cyanobacterial cell densities cause increased microcystin levels. In this study, three microcystin-producing strains were processed using no cell enrichment steps (by direct freezing at three temperatures) and with biomass enrichment (by centrifugation or GF/C filtration). After extraction, microcystins were analyzed using liquid chromatography-tandem mass spectrometry. All processing methods tested, except GF/C filtration, resulted in comparable microcystin quotas for all strains. The low yields observed for the filtration samples were caused by adsorption of arginine-containing microcystins to the GF/C filters. Whilst biomass enrichment did not affect microcystin metabolism over the time-frame of normal sample processing, problems associated with GF/C filtration were identified. The most widely applicable processing method was direct freezing of samples as it could be utilized in both field and laboratory environments.
authors.affiliation: Department of Chemistry, School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. sr110@students.waikato.ac.nz.|Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. sr110@students.waikato.ac.nz.
authors.forename: Shelley
authors.initials: S
authors.lastname: Rogers
authors.affiliation: Cawthron Institute, Private Bag 2, Nelson 7010, New Zealand. jonathan.puddick@cawthron.org.nz.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Puddick
authors.affiliation: Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. susie.wood@cawthron.org.nz.|Cawthron Institute, Private Bag 2, Nelson 7010, New Zealand. susie.wood@cawthron.org.nz.
authors.forename: Susanna A
authors.initials: SA
authors.lastname: Wood
authors.affiliation: Human and Environmental Toxicology, University of Konstanz, P.O. Box 662, 78457 Konstanz, Germany. daniel.dietrich@uni-konstanz.de.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Dietrich
authors.affiliation: Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. d.hamilton@waikato.ac.nz.
authors.forename: David P
authors.initials: DP
authors.lastname: Hamilton
authors.affiliation: Department of Chemistry, School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand. m.prinsep@waikato.ac.nz.
authors.forename: Michele R
authors.initials: MR
authors.lastname: Prinsep
mesh_terms: D018533:Biomass; D002498:Centrifugation; D002853:Chromatography, Liquid; D000458:Cyanobacteria / Q000737:chemistry*; D005374:Filtration; D052998:Microcystins / Q000032:analysis*; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry
chemical_list: D052998:Microcystins; C078588:microcystin