Differences in the cellular dry weight per unit biovolume of Phormidium autumnale (Cyanobacteria) dependent on growth conditions

Abstract

The influence of substrate, light intensity, temperature and growth phase on the dry weight per unit biovolume of both living Phormidium autumnale trichomes and living single cells was investigated microinterferometrically. With a Mach-Zehnder Interference Microscope, both the interference-stripe-field method and the phase-shift method were used to measure the optical path differences (OPD) of cells and trichomes. To calculate the cellular dry weight of trichomes, the trichome diameters have to be measured. Widths between 4 and 7 µm were determined. Thick trichomes are characteristic for growth on agar-solidified medium, whereas this was observed in single cases only from trichomes growing on soil surfaces. A reliable prediction of trichome width from growth conditions is not possible. The dry weights per unit biovolume (fg µm-3) are independent of the studied parameters during the exponential growth phase (296 ± 22 fg µm-3) with exception of the agar-based cultures growing at low light intensity (259 ± 16 fg µm-3). During the stationary phase, dry weights per unit biovolume increase independently of growth conditions (353 ± 39 fg µm-3). Two separate factors of 0.14 and 0.17 for converting biovolume (mm3) of cells to milligrams carbon could be determined by comparing the growth phase and stationary phase-dependent average values of dry weights per unit biovolume, respectively. These conversion factors could be used as species-specific factors for Phormidium growing on soil surfaces. Irrespective of the method, both the stripe-field and phase-shift method gave similar results. However, the phase-shift method measured lower variances of values. Additionally, detailed quantifying investigations of structures within cells are possible. Thus, the phase-shift method could be a powerful analytical tool in, e.g., ecotoxicological monitoring analyses

Combined effect of temperature and bleaching herbicides on photosynthesis, pigment and fatty acid composition ofChlamydomonas reinhardtii

“…2). Jahnke & Mahlmann (2010) also observed a decrease in dry weight per unit biovolume when Phormidium autumnale was grown under low light compared with high light, a condition that also decreased the growth rate and photosynthesis of various phytoplankton species (Deblois et al, 2013).…”

The influence of growth conditions on the cell dry weight per unit biovolume of Klebsormidium flaccidum (Charophyta), a typical ubiquitous soil alga

“…Thus, it could be expected that both beneficial and inhibitory effects on dw/ubv will be distinguishable. As shown on P. autumnale (Jahnke and Mahlmann 2010), measurements for ecotoxicological purposes are well done approx. 10 days after inoculation.…”

“…The unialgal culture was not axenic. For interferometric measurements, subcultures spread on different substrates (Table 1) in Petri dishes were incubated at different temperature and light regimes as described previously (Jahnke et al 2007;Jahnke and Mahlmann 2010). Photon flow density was, with the exception of experiments 1, 12 and 74 (Table 2), 230 μmol photons m −2 s −1 (spherical sensor, QSL 100 Biosphaerical Instr.…”

“…The interferometric measurements of cells, calculations and the determinations of biovolumes were carried out according to Mahlmann et al (2008) and Jahnke and Mahlmann (2010). In a Mach-Zehnder interference microscope (Leitz), the microscopic picture (objective 50/0.85) of an algae ( Fig.…”

“…However, the physiological conditions of cells cause fluctuations in cellular dry weight and therefore cellular carbon (Reynolds 1984;Paul and Clark 1989;Paul et al 1999;Stramski 1999;Bölter et al 2006). Transmitted light interference microscopy has been used for measuring dry weight per unit biovolume (mean dry weight per 1 μm −3 of cell volume) of cultured and in situ, living, single cyanobacterial cells of different species (Mahlmann et al 2008) and of cultivated Phormidium autumnale (Jahnke and Mahlmann 2010). It was shown that dry weight/unit biovolume (dw/ubv) of a Phormidium strain depended on growth conditions and varied by a factor of 1.9.…”