Flow cytometric applicability to evaluate UV inactivation of phytoplankton in marine water samples

Dual staining with CFDA-AM and SYTOX Blue in flow cytometry analysis of UV-irradiated Tetraselmis suecica to evaluate vitality

“…To inactivate the algae, a collimated medium pressure (MP; 800 W) UV lamp (BestUV) with a polychromatic (200−400 nm) mercury lamp was used (Olsen et al 2015). The UV-C intensity was 0.525 mW cm −2 , and the weighted average germicidal factor, based on the absorbance spectrum of DNA from Bacillus subtilis (Chen 2009), was 0.5799.…”

“…The fluorescent product is retained in cells with intact membranes, and the fluorescence intensity is correlated with the metabolic activity. Esterase substrates are commonly used in FCM studies of phytoplankton (Garvey et al 2007, Steinberg et al 2011, Gorokhova et al 2012, Peperzak & Gollasch 2013, Olsen et al 2015.…”

“…Previously, we developed an FCM protocol to discriminate dead Tetraselmis suecica from live and UV damaged cells (Olsen et al 2015). Prior to FCM analysis, the alga was stained with CFDA-acetoxy -methyl ester (CFDA-AM), which is hydrolyzed to carboxyfluorescein in esterase active cells.…”

“…The aim of the study was to improve our previously developed FCM protocol (Olsen et al 2015) to evaluate the performance of UV-based water treatment techniques and overcome the challenges described above. In order to do so, we aimed at answering the following questions:…”

Evaluation of ultraviolet disinfection of microalgae by growth modeling: application to ballast water treatment

“…According to the BWMC-Guideline 8, the evaluation of the treatment efficacy is based on the determination of living organisms by widely accepted standard methods (Gollasch et al 2012;Cullen and MacIntyre 2016), such as vital fluorescence stains detected using flow cytometry or fluorescence microscopy, ATP content, photosynthetic activity, or motility assessment (Hessen et al 1997;Sato et al 2004;Gavand et al 2007;Gallo-Villanueva et al 2011;Steinberg et al 2011Steinberg et al , 2012Fan et al 2013;Martínez et al 2013;Stehouwer et al 2013;Adams et al 2014;First and Drake 2014;Tilney et al 2014;Feng et al 2015;Gollasch et al 2015;Olsen et al 2015;van Slooten et al 2015;Wright et al 2015). However, the application of UV treatment does not cause immediate changes in the concentration of living organisms, although their growth curves become different over the time, depending on the applied UV dose (Tao et al 2010;Gorokhova et al 2012;Martínez et al 2012).…”