Absolute amount of phycocyanin per gram dry weight (gDW) with increasing growth rate (see 'Comments' section)

Range 86.4±30.7 mg/gDW to 26.5±7.5 mg/gDW
Organism Cyanobacteria Synechocystis PCC 6803
Reference Zavřel T et al., Quantitative insights into the cyanobacterial cell economy. Elife. 2019 Feb 4 8. pii: e42508. DOI: 10.7554/eLife.42508 p.6 6th paragraphPubMed ID30714903
Method P.2 bottom paragraph: "The Synechocystis substrain GT-L (Zavřel et al., 2015b) was cultivated in flat panel photobioreactors (Figure 1A) using at least 5 independent reactors in a quasi-continuous (turbidostat) regime (Figure 1B), with red light intensities of 27.5 − 1100 μmol(photons) m^-2s^-1, supplemented with a blue light intensity of 27.5 μmol(photons) m^-2s^-1. The addition of blue light avoids possible growth limitations in the absence of short wavelength photons (Golden, 1995). Steady-state specific growth rates in turbidostat mode were calculated from monitoring the optical density measured at a wavelength of 680 nm (OD680) as well as from the rate of depletion of spare cultivation medium (as measured by top loading balances). Both methods resulted in similar average values (Figure 1C). Estimation of the specific growth rates based on the medium depletion, however, exhibited higher variance. For further analysis, therefore, only values obtained from the OD680 signal are reported."
Comments P.6 6th paragraph: "Relative to gDW, the amounts of phycobiliproteins, chlorophyll a and carotenoids decreased with increasing growth rate. Under conditions of photoinhibition, [investigators] observed additional reduction of these pigments per gDW (Figure 2K,M). When considering the concentrations per cell, however, the respective amounts initially increased with increasing growth rates, and decreased again under conditions of photoinhibition. Overall, pigment content decreased with increasing light intensity (irrespective of normalization), with the exception of carotenoids that exhibited a slight increase per cell as a function of light intensity. The changes of pigment amounts as a function of growth rate (relative to gDW as well as per cell) were significant (Kruskal-Wallis test: p−value<0.05, see Materials and methods for further details). The absolute amounts of phycocyanin were between 86.4±30.7 and 26.5±7.5 mg/gDW, corresponding to 172±29 and 620±63 fg/cell (Figure 2K,L), the amounts of allophycocyanin were between 14.8±5.3 and 6.7±1.9 mg/gDW, corresponding to 57±10 and 123±15 fg/cell (Figure 2K,L)." Comment from Ron Milo: "Based on reported mass and volume the density seems too high and thus there might be some problem."
Entered by Uri M
ID 116741