New approach in studies of microalgal cell lysis

Abstract

Abstract:A new approach to the studies of the microalgal cell lysis by utilizing a combination of two complementary methods is presented.Delayed fluorescence (DF) is a measure of the living algal biomass, detecting only cells with active photosynthesis. Thermal lens spectrometry (TLS) detects the total pigment amount released from lysed cells. Both methods select for photosynthetic organisms, reducing possible background from other sources (e.g. heterotrophic bacteria, zooplankton, and abiotic substances). The DF/TLS method was tested with a laboratory Skeletonema costatum culture exposed to a geometric dilution series of the lysing factor poly-APS. The exposure resulted in similar EC 50 values for DF intensity, TLS and dissolved esterase activity of 0.8±0.2, 1.77±0.35, and 1.25±0.1 mg poly-APS l -1 , respectively. The combined DF/TLS method enabled a rapid evaluation of the living vs. dead cells without any sample pretreatment or manipulation.

Fast Screening Techniques for Neurotoxigenic Substances and Other Toxicants and Pollutants Based on Thermal Lensing and Microfluidic Chips

“…69 In our work, which in a similar way aimed to use carotenoids from phytoplankton cell cytoplasm as an indicator of massive algal blooms, TLS detection enabled highly sensitive online monitoring of the lysis of cultured cells (Skeletonema costatum), with a limit of detection corresponding to 6 × 10 6 lysed cells/L (equivalent to a β-carotene concentration of 0.6 μg/L). 70,71 With the FIA-TLS detection of Cr-PE, a LOD of 12 μg/L was achieved for this cyanopigment. Taking into account that on average 5 × 10 6 cyanobacteria produce 1 μg/L microcystin in water, 72 and considering the dry weight of cyanobacteria (264 fg/μm 3 ) 73 and the amount of PE in cyanobacterial cells (up to 8% dry weight), 74 a comparable concentration of 6.4 μg/L Cr-PE corresponds to the maximum contaminant level (MCL) for microcystin (1 μg/L).…”

Photosynthesis in Microalgae as Measured with Delayed Fluorescence Technique

“…Delayed fluorescence intensity (DFI) is represented by an integral under the DF decay curve. In many cases, DFI can be utilized as a measure of living cell concentration (Berden- Zrimec et al, 2009). It also reflects the number of PSII centers, the fluorescence yield, and the rate of back reactions, which are influenced by the membrane potential and pH gradient (Avron & Schreiber, 1979;Joliot et al, 1971;Joliot & Joliot, 1980;Wraight & Crofts, 1971).…”

“…The changes in chemical and physical parameters affect the reduction state of the plastoquinone pool or its coupling with PSII by modulating the reversed electron flow (Avron & Schreiber, 1979;Mellvig & Tillberg, 1986). In the field studies, the intensity of delayed fluorescence is used as a measure of photosynthetic activity and living algal biomass (Berden-Zrimec et al, 2009;Krause & Gerhardt, 1984;Kurzbaum et al, 2007;Schneckenburger & Schmidt, 1996). Additionally, DF excitation spectra can be utilized for the analysis of taxonomical changes in the algal communities (Greisberger & Teubner, 2007;Hakanson et al, 2003;Istvanovics et al, 2005;Yacobi et al, 1998) (Figure 1).…”

Recent Progress and Applications of Thermal Lens Spectrometry and Photothermal Beam Deflection Techniques in Environmental Sensing

“…Recently, TLS and BDS were successfully applied for environmental monitoring and investigations of environmental processes and conditions by determining specific compounds and ions in natural and wastewaters and for speciation studies of elements in waters and sediments. The range of analytes determined by TLS in environmental samples ranges from toxic compounds and elements, such as for example pesticides, colloidal Ag and Cr(VI), or markers/indicators of undesired environmental processes like algal blooms (carotenoids, phthalocyanines), degradation of organic matter (ammonia, biogenic amines) or anoxic conditions in aquatic systems (Fe(II)/Fe(III)) [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Several other applications of TLS in the analysis of environmental and related samples can be found in previous review papers and book chapters [ 20 , 21 , 22 , 23 , 24 , 25 ].…”