title: A small volume bioassay to assess bacterial/phytoplankton co-culture using WATER-Pulse-Amplitude-Modulated (WATER-PAM) fluorometry.
abstract: Conventional methods for experimental manipulation of microalgae have employed large volumes of culture (20 ml to 5 L), so that the culture can be subsampled throughout the experiment1-7. Subsampling of large volumes can be problematic for several reasons: 1) it causes variation in the total volume and the surface area:volume ratio of the culture during the experiment; 2) pseudo-replication (i.e., replicate samples from the same treatment flask8) is often employed rather than true replicates (i.e., sampling from replicate treatments); 3) the duration of the experiment is limited by the total volume; and 4) axenic cultures or the usual bacterial microbiota are difficult to maintain during long-term experiments as contamination commonly occurs during subsampling. The use of microtiter plates enables 1 ml culture volumes to be used for each replicate, with up to 48 separate treatments within a 12.65x8.5x2.2 cm plate, thereby decreasing the experimental volume and allowing for extensive replication without subsampling any treatment. Additionally, this technique can be modified to fit a variety of experimental formats including: bacterial-algal co-cultures, algal physiology tests, and toxin screening9-11. Individual wells with an alga, bacterium and/or co-cultures can be sampled for numerous laboratory procedures including, but not limited to: WATER-Pulse-Amplitude-Modulated (WATER-PAM) fluorometry, microscopy, bacterial colony forming unit (cfu) counts and flow cytometry. The combination of the microtiter plate format and WATER-PAM fluorometry allows for multiple rapid measurements of photochemical yield and other photochemical parameters with low variability between samples, high reproducibility and avoids the many pitfalls of subsampling a carboy or conical flask over the course of an experiment.
authors: Department of Biological Sciences, University of Alberta.
authors: Anna R
authors: AR
authors: Bramucci
authors: Department of Biological Sciences, University of Alberta.
authors: Leen
authors: L
authors: Labeeuw
authors: Department of Biological Sciences, University of Alberta.
authors: Teaghan J
authors: TJ
authors: Mayers
authors: Department of Biological Sciences, University of Alberta.
authors: Julie A
authors: JA
authors: Saby
authors: Department of Biological Sciences, University of Alberta; rcase@ualberta.ca.
authors: Rebecca J
authors: RJ
authors: Case
mesh_terms: D001419:Bacteria / Q000166:cytology*; D001681:Biological Assay / Q000379:methods; D018920:Coculture Techniques / Q000379:methods*; D005470:Fluorometry / Q000379:methods*; D058086:Microalgae / Q000166:cytology*; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism; D015203:Reproducibility of Results; D014867:Water / Q000737:chemistry
chemical_list: D045332:Photosystem II Protein Complex; D014867:Water