Light attenuation changes with photo-acclimation in a culture of Synechocystis sp. PCC 6803

Abstract

designed the experiments, collected the data, and did the primary analysis, interpretation, and reporting of the data. Bruce Rittmann provided further insight for data analysis, interpretation, and reporting. Both wrote the manuscript cooperatively.

Growth kinetics and mathematical modeling of Synechocystis sp. PCC 6803 under flashing light

“…As the concentration of a culture of microalgae (collectively referring to single-celled algae and cyanobacteria) increases, the biomass is subject to larger swings in local light intensity (LI) as it moves from areas of high LI (near the light source) to low or no LI (in the interior of a photobioreactor or depths of a lake) (Janssen, Slenders, Tramper, Mur, & Wijffels, 2001;Straka & Rittmann, 2017). The effect that rapid changes in local LI have on the microalgae's phototrophic growth rate is not obvious, because the cells' statuses in terms of photoacclimation and photodamage are continually changing (reviewed in Straka & Rittmann, 2018a).…”

“…The extinction coefficient (ε) was measured daily by the method reported by Straka and Rittmann (2017). The extinction coefficient (ε) was measured daily by the method reported by Straka and Rittmann (2017).…”

Effect of culture density on biomass production and light utilization efficiency of Synechocystis sp. PCC 6803

“…The culture density where this maximum occurs varies widely depending on the light intensity and species (Goldman, ; Hu et al, ). While the initial increase can be explained by an increase in light‐utilization efficiency (Straka & Rittmann, ), it occurs along with a decrease in the specific growth rate due to decreased light availability (Goldman, ; Hewes, ). The general explanation for the decrease in biomass production at high culture density is that, as the specific growth rate becomes smaller, the rate of endogenous decay becomes comparatively more significant, which causes a net decrease in light utilization efficiency (Goldman, ; Hewes, ).…”

“…As culture density increases, the “light regime” causes rapid changes in light intensity due to mixing, causing photoacclimation. One simple way to detect changes in photoacclimation is through changes in the ratio of optical density at 680 versus 735 nm (i.e., the OD 680 /OD 735 ratio) (Straka & Rittmann, ). Light irradiance at 680 nm is absorbed well by chlorophyll a, but 735 nm is not; therefore, a shift in OD 680 /OD 735 signals a change in relative chlorophyll content (Griffiths, Garcin, van Hille, & Harrison, ).…”

“…Figure a shows an obvious decline in µ as X increased, and it correlates to the corresponding decline in LI ave (Figure b). Changes in OD 680 /OD 735 (Figure c) indicate a change in pigmentation, and, therefore, a change in photoacclimation (Straka & Rittmann, ). OD 680 /OD 735 increased with larger X, a trend that is expected because lower light availability induces Synechocystis cells to optimize their light absorption to the low light condition by adding pigmentation.…”