Chlorophyll fluorescence induction and relaxation system for the continuous monitoring of photosynthetic capacity in photobioreactors

The development of high‐performance photobioreactors equipped with automatic systems for non‐invasive real‐time monitoring of cultivation conditions and photosynthetic parameters is a challenge in algae biotechnology. Therefore, we developed a chlorophyll (Chl) fluorescence measuring system for the online recording of the light‐induced fluorescence rise and the dark relaxation of the flash‐induced fluorescence yield (Qa^? ? re‐oxidation kinetics) in photobioreactors. This system provides automatic measurements in a broad range of Chl concentrations at high frequency of gas‐tight sampling, and advanced data analysis. The performance of this new technique was tested on the green microalgae Chlamydomonas reinhardtii subjected to a sulfur deficiency stress and to long‐term dark anaerobic conditions. More than thousand fluorescence kinetic curves were recorded and analyzed during aerobic and anaerobic stages of incubation. Lifetime and amplitude values of kinetic components were determined, and their dynamics plotted on heatmaps. Out of these data, stress‐sensitive kinetic parameters were specified. This implemented apparatus can therefore be useful for the continuous real‐time monitoring of algal photosynthesis in photobioreactors.     

Fluorescence clamp: A direct measure of fluxes into and out of the antenna pool of Photosystem II

Fluorescence clamp (FC) is a method of directly measuring the fluxes out of Photosystem II antenna. This is achieved by a feed-back loop which controls the light intensity of light emitting diodes in order to keep the amplitude of modulated chlorophyll fluorescence constant, and by taking the intensity or the current fed into the light emitting diodes as a measure of the fluxes. Saturating flashes serve to distinguish between fluxes into thermal deactivation and into the photosynthetic electron transfer chain (ETC). As FC is only active in the light period of the measuring light, the background signal (induced by actinic light) is compensated by a second feed-back loop in the dark period of the measuring light. Equations are provided for the interpretation of the FC signals. This includes the quenching parameters of chlorophyll fluorescence, the flux into the electron transfer chain and the redox state of Q_A. Experiments are presented which show that traditional fluorescence (LC) and FC measurements yield the same results. However, the FC method provides a better presentation of fluxes as the scaling factor (flux/signal) is constant for all states of Photosystem II. This leads to a simpler analysis of quenching mechanisms. Examples are given which show that the co-existing quenching mechanisms with different effects on photochemical and non-photochemical fluxes can be better identified by FC rather than by LC. This revised version was published online in June 2006 with corrections to the Cover Date.     

Possibilities of Optical Monitoring of Phosphorus Starvation in Suspensions of Microalga <Emphasis Type="Italic">Chlorella vulgaris</Emphasis> IPPAS C-1 (Chlorophyceae)

Studies of the impact of inorganic phosphorus (P_i), an important nutrient, on the growth and physiological parameters of single-celled algae are important for investigations of the dynamics of phytoplankton abundance and productivity in natural ecosystems as well as in industrial systems for the cultivation of microalgae. Difficulties in carrying out such studies are associated with the complex kinetics of P_i uptake by cells and the ability of microalgae to store phosphorus in their cells. This situation necessitates efficient methods for express monitoring of microalgal cultures, such as the methods based on the registration of optical properties of cells, in particular absorption and scattering of light and fluorescence of chlorophyll contained in the cells. Here, the results of monitoring the cultures of the chlorophyte Chlorella vulgaris IPPAS C-1 starving for phosphorus are described. It was found that both optical (light absorption in the bands of the key pigments—chlorophylls and carotenoids) and luminescent (variable fluorescence of chlorophyll) parameters closely reflect the culture condition. Registration of optical properties required correction for the contribution of light scattering to the overall extinction of light by microalgal cell suspensions. At the same time, the light scattering signal is an accurate measure of the total number of suspended particles in the suspension. However, it is difficult to monitor cultures containing a significant amount of light-scattering particles lacking photosynthetic pigments (such as heterotrophic bacteria). For such cultures, the use of variable fluorescence- based parameter Fv/Fm reflecting the maximum photochemical efficiency of the photosystem II is advisable.     

Microalgae Improve the Photosynthetic Performance of Rice Seedlings (<i>Oryza sativa</i> L.) under Physiological Conditions and Cadmium Stress

The aim of this study was to assess the impact of the microalgae Chlorella vulgaris on the rice seedlings at physiological conditions and under cadmium (Cd) stress. We examined the effects of C. vulgaris in the nutrient solution on rice seedlings grown hydroponically in the presence and the absence of 150 μM CdCl₂, using the low (77 K) temperature and pulse amplitude modulated (PAM) chlorophyll fluorescence, P700 photooxidation measurements, photochemical activities of both photosystems, kinetic parameters of oxygen evolution, oxidative stress markers (MDA, H₂O₂ and proline), pigment content, growth parameters and Cd accumulation. Data revealed that the application C. vulgaris not only stimulates growth and improves the functions of photosynthetic apparatus under physiological conditions, but also reduces the toxic effect of Cd on rice seedlings. Furthermore, the presence of the green microalgae in the nutrient solution of the rice seedlings during Cd exposure, significantly improved the growth, photochemical activities of both photosystems, the kinetic parameters of the oxygen-evolving reactions, pigment content and decreased lipid peroxidation, H₂O₂ and proline content. Data showed that the alleviation of Cd-induced effects in rice seedlings is a result of the Cd sorption by microalgae, as well as the reduced Cd accumulation in the roots and its translocation from the roots to the shoots.     

Fluorescence induction curves registered from individual microalgae cenobiums in the process of population growth

Registration of chlorophyll fluorescence induction curves (IC) from individual microalgae cenobiums was performed during Scenedesmus quadricauda culture growth. Emphasis was placed on the analysis of patterns of the slow phase of IC, since these slow fluorescence transitions reflect complex interactions between primary and secondary photosynthetic processes. A classification was performed of the ICs obtained according to the patterns of their slow phase. Four different types of such patterns were distinguished. The microalgae population structure with respect to IC patterns was investigated at different stages of culture growth. The distribution of microalgae cenobiums over the patterns of IC was found to change in accordance with the stage of population development. At the stage of the population growth enhancement, nonmonotonous IC dominated with a high steady-state level of fluorescence. The stage of linear growth was characterized by IC with monotonous decay kinetics and low steady-state level of fluorescence. At the third stage including the phases of growth inhibition, stationary state and the beginning of cell death the population structure was the most heterogeneous, with all IC patterns observed.Abbreviations CO₂ carbon dioxide - ETC electron transfer chain - Fl fluorescence - FNR ferredoxin-NADPH reductase - IC induction curve of chlorophyll fluorescence - PQ plastoquinone - PS I Photosystem I - PS II Photosystem II - Q_A primary quinone acceptor of PS II     

Progress in physicochemical parameters of microalgae cultivation for biofuel production

Microalgae have been exploited for biofuel generation in the current era due to its enormous energy content, fast cellular growth rate, inexpensive culture approaches, accumulation of inorganic compounds, and CO₂ sequestration. Currently, research is ongoing towards the advancement of the microalgae cultivation parameters to enhance the biomass yield. The main objective of this study was to delineate the progress of physicochemical parameters for microalgae cultivation such as gaseous transfer, mixing, light demand, temperature, pH, nutrients and the culture period. This review demonstrates the latest research trends on mass transfer coefficient of different microalgae culturing reactors, gas velocity optimization, light intensity, retention time, and radiance effects on microalgae cellular growth, temperature impact on chlorophyll production, and nutrient dosage ratios for cellulosic metabolism to avoid nutrient deprivation. Besides that, cultivation approaches for microalgae associated with mathematical modeling for different parameters, mechanisms of microalgal growth rate and doubling time have been elaborately described. Along with that, this review also documents potential lipid-carbohydrate-protein enriched microalgae candidates for biofuel, biomass productivity, and different cultivation conditions including open-pond cultivation, closed-loop cultivation, and photobioreactors. Various photobioreactor types, the microalgae strain, productivity, advantages, and limitations were tabulated. In line with microalgae cultivation, this study also outlines in detail numerous biofuels from microalgae.     

Photosynthetic control, “energy-dependent” quenching of chlorophyll fluorescence and photophosphorylation under influence of tertiary amines

The effects of the tertiary amines tetracaine, brucine and dibucaine on photophosphorylation and control of photosynthetic electron transport in isolated chloroplasts of Spinacia oleracea were investigated. Tertiary amines inhibited photophosphorylation while the related electron transport decreased to the rates, observed under non-phosphorylating conditions. Light induced quenching of 9-aminoacridine fluorescence and uptake of ¹⁴C-labelled methylamine in the thylakoid lumen declined in parallel with photophosphorylation, indicating a decline of the transthylakoid proton gradient. In the presence of ionophoric uncouplers such as nigericin, no effect of tertiary amines on electron transport was seen in a range of concentration where photophosphorylation was inhibited. Under the influence of the tertiary amines tested, pH-dependent feed-back control of photosystem II, as indicated by energy-dependent quenching of chlorophyll fluorescence, was unaffected or even increased in a range of concentration where 9-aminoacridine fluorescence quenching and photophosphorylation were inhibited. The data are discussed with respect to a possible involvement of localized proton flow pathways in energy coupling and feed-back control of electron transport.Abbreviations 9-AA 9-aminoacridine - J _e flux of photosynthetic electron transport - PC photosynthetic control - pH₁ H⁺ concentration in the thylakoid lumen - pmf proton motive force - _P potential quantum yield of photochemistry of photosystem II (with open reaction centers) - Q _A primary quinone-type electron acceptor of photosystem II - q _Q photochemical quenching of chlorophyll fluorescence - q _E energy-dependent quenching of chlorophyll fluorescence - q _AA light-induced quenching of 9-amino-acridine fluorescence     

Temporal characteristics of chlorophyll fluorescence quenching and dissolved oxygen concentration as indicators of photosynthetic activity in Chlorella emersonii

A simple chlorophyll fluorescence (CF) measuring system has been implemented to study temporal characteristics of chlorophyll fluorescence induction (CFI) in dark-adapted freshwater algal cultures of Chlorella emersonii. There were two different decay time constants describing the CF quenching: τ₀ (the faster) and τ₁ (the slower) with amplitudes A₀ and A₁, respectively. The relative amplitude of the faster quenching component decreased once the sample was subject to deprivation from dissolved oxygen (DO). The DO concentration of samples was monitored to validate the effects of deprivation from air contact for up to 7 d and to the effect of adding DCMU to the culture (herbicide for blocking electron transport of photosystem 2). CFI analysis and DO measurements showed that the relative amplitude of A₀ to (A₀ + A₁) and the DO concentration can be used as an indication of relative photosynthetic activity, thus allowing for the possibility to classify the physiological state of algal blooms into active and inactive states.     

Regulation of the body-substrat-distance in the stick insect: Responses to sinusoidal stimulation

The stick insect Carausius morosus maintains the distance between the substrate and its body. The underlying feed-back servo mechanism has been analyzed in intact animals under open loop conditions by changing the body-substrate distance in a sinusoidal fashion. The center position z _c has been varied as parameter and the force the animal elicits along its high axis has been measured. The response amplitude A is a nonlinear function of z _c. This nonlinear relationship between A and z _c is most probably caused by the relationship between the torque excerted at the joints and the measured force. The responses to sinusoidal stimulation reveal band-pass character of the feed-back loop. Due to the nonlinearity of the system the average value of the response to sinusoidal disturbances depends upon the frequency of modulation. The change of the average value with the frequency of modulation is partially due to cocontraction of the extensor and flexor muscles.     

Ultrahigh-cell-density heterotrophic cultivation of the unicellular green microalga Scenedesmus acuminatus and application of the cells to photoautotrophic culture enhance biomass and lipid production

Although production of biodiesels from microalgae is proved to be technically feasible, a commercially viable system has yet to emerge. High-cell-density fermentation of microalgae can be coupled with photoautotrophic cultivation to produce oils. In this study, by optimizing culturing conditions and employing a sophisticated substrate feed control strategy, ultrahigh-cell-density of 286 and 283.5 g/L was achieved for the unicellular alga Scenedesmus acuminatus grown in 7.5-L bench-scale and 1,000-L pilot-scale fermenters, respectively. The outdoor scale-up experiments indicated that heterotrophically grown S. acuminatus cells are more productive in terms of both biomass and lipid accumulation when they are inoculated in photobioreactors for lipid production as compared to the cells originally grown under photoautotrophic conditions. Technoeconomic analysis based on the pilot-scale data indicated that the cost of heterotrophic cultivation of microalgae for biomass production is comparable with that of the open-pond system and much lower than that of tubular PBR, if the biomass yield was higher than 200 g/L. This study demonstrated the economic viability of heterotrophic cultivation on large-scale microalgal inocula production, but ultrahigh-productivity fermentation is a prerequisite. Moreover, the advantages of the combined heterotrophic and photoautotrophic cultivation of microalgae for biofuels production were also verified in the pilot-scale.     

Biological constraints in algal biotechnology

In the past decade, considerable progress has been made in developing the appropriate biotechnology for microalgal mass cultivation aimed at establishing a new agro-industry. This review points out the main biological constraints affecting algal biotechnology outdoors and the requirements for making this biotechnology economically viable. One of them is the availability of a wide variety of algal species and improved strains that favorably respond to varying environmental conditions existing outdoors. It is thus just a matter of time and effort before a new methodology like genetic engineering can and will be applied in this field as well. The study of stress physiology and adaptation of microalgae has also an important application in further development of the biotechnology for mass culturing of microalgae. In outdoor cultures, cells are exposed to severe changes in light and temperature much faster than the time scale required for the cells to acclimate. A better understanding of those parameters and the ability to rapidly monitor those conditions will provide the growers with a better knowledge on how to optimize growth and productivity. Induction of accumulation of high value products is associated with stress conditions. Understanding the physiological response may help in providing a better production system for the desired product and, at a later stage, give an insight of the potential for genetic modification of desired strains. The potential use of microalgae as part of a biological system for bioremediation/detoxification and wastewater treatment is also associated with growing the cells under stress conditions. Important developments in monitoring and feedback control of the culture behavior through application of on-line chlorophyll fluorescence technique are in progress. Understanding the process associated with those unique environmental conditions may help in choosing the right culture conditions as well as selecting strains in order to improve the efficiency of the biological process.     

Damage of PS II during senescence of Spirodela polyrrhiza explants under long-day conditions and its prevention by 6-benzyladenine

The chlorophyll a (Chl a) fluorescence technique was applied to investigate damage of PS II during senescence of excised half-fronds in Spirodela polyrrhiza P143. The green explants showed a typical Chl a fluorescence transient, OJIP. After cultivation of explants under long-day conditions for 8 days, all the J, I, and P steps disappeared, but a clear K band, an indication of senescence, was observed. JIP-test showed that at this time point, the photosynthetic performance index (PI) dropped to zero and the active reaction center (RC) per leaf cross-section (RC/CS) declined to 18%. As the oxygen-evolving complex (OEC) and the chlorophyll content all remained above 42%, it is proposed that the decline in RC contributes more to the appearance of the K band. Supplementation of 6-benzyladenine (6-BA) into the medium at the beginning of cultivation caused dramatic increase in PI, OEC, RC/CS, and chlorophyll content, and at any time before the 8th day reversed the senescence process of the explants. When 6-BA was added after 8 days of cultivation, the PI did not increase anymore, RC/CS and OEC were maintained at 22% and above 40%, respectively, and chlorophyll content decreased continuously further. These data support a view that the decline in RC is crucial for initiation of the irreversible senescence phase of explants cultivated under long-day conditions.     

Dynamics of luminescence characteristics of Haematococcus lacustris cultures in different cultivation conditions

Luminescence of microalgae cultures is a valuable property for the fast diagnostics of their physiological state; however, it has been rarely used in algaculture practice. In this work, luminescence spectrum characteristics of two-stage batch cultures of the green carotenogenic microalga Haematococcus lacustris (Girod-Chantrans) Rostafinski 1875 (Chlorophyceae, Chlamydomonadales) under conditions of autotrophic and mixotrophic growth were investigated. The dynamics of the heterotrophy indices in cultures at different stages of their development in different growth media was determined. The transition of H. lacustris cultures from the initially autotrophic to mixotrophic growth regime was registered during the induction of the astaxanthin biosynthesis by complex physicochemical stressing, including nutritional deficiencies, exposure to high concentrations of sodium acetate and chloride and increased illuminance and temperature. The applicability of luminescence spectrometry in vivo for a rapid assessment of the state of H. lacustris cultures in various growth media and with different methods of secondary carotenogenesis induction was shown. The results obtained can be used in experimental studies on optimizing cultivation methods for this species, as well as for the express control of the physiological state of its industrial cultures.     

Physiological and Biochemical Changes in Microcystis aeruginosa Qutz. in Phosphorus Limitation

Effects of phosphorus limitation on the physiological and biochemical changes of the freshwater bloom alga Microcystis aeruginosa Qutz. are reported in the present study. As a result of phosphorus limitation, biomass was controlled to some extent and the protein content per cell in vivo decreased. However,the carbohydrate content per cell was higher in phosphorus limitation over the 8d of cultivation. Soluble proteins were distinct in the media, whereas phosphorus deficiency induced the presence of a unique protein (16.2 kDa). Under conditions of phosphorus limitation, the activities of both superoxide dismutase and peroxidase per cell in vivo were lower than under normal conditions in the last cultivation. The in vivo absorption spectra of cells showed chlorophyll absorption peaks at 676 and 436nm, over 10nm red-shifted from the normal position; cells showed an absence of a chlorophyll c with an in viva absorption peak at 623nm and an extraction absorption peak at 617nm. The chlorophyll a/carotene and chlorophyll a/xanthophylls ratios decreased under conditions of phosphorus limitation, photosynthetic efficiency (Fv/Fm) was clearly lower, and the low-temperature fluorescence emission spectra indicated a higher peak at 683nm and a lower peak at 721nm relatively, with the 721nm peak drifting slightly to the red and the 683 nm peak strengthened with a weakened 692nm shoulder peak.     

Human optokinetic responses under quasi-open and closed loop conditions

The human optokinetic response to a horizontally moving striped pattern surrounding the subject was investigated under quasi-open and closed loop conditions. Open loop conditions were produced by the addition of an external signal from measured slow phase eye velocity to stripe velocity. A comparison of open and closed loop responses to step and sinusoidal changes of stripe velocity indicates that the central nervous system controlling slow phase optokinetic following can be described as a simple first order lag (Ka/(s+a)) where K is 4.7 and the time constant, 1/a, is 1.25 s.     

Efficacy of Chlorella pyrenoidosa and Scenedesmus abundans for Nutrient Removal in Rice Mill Effluent (Paddy Soaked Water)

Microalgae are product of sustainable development owing to its ability to treat variety of wastewater effluents and thus produced biomass can serve as value added product for various commercial applications. This paper deals with the cultivation of microalgae species namely Chlorella pyrenoidosa and Scenedesmus abundans in rice mill effluent (i.e., paddy soaked water) for nutrient removal. In order to investigate the nutrient removal capability, microalgae are subjected to cultivation in both raw and autoclaved samples. The maximum phosphate removal by Scenedesmus abundans and Chlorella pyrenoidosa in raw sample was 98.3% and 97.6%, respectively, whereas, the removal of ammoniacal nitrogen by Scenedesmus abundans and Chlorella pyrenoidosa in raw sample was 92% and 90.3%, respectively. The growth (measured in terms of chlorophyll content) of Scenedesmus abundans and Chlorella pyrenoidosa in raw sample was 3.88 mg/l and 5.55 mg/l, respectively. The results indicate the suitability of microalgae cultivation in rice mill effluent treatment for nutrient removal.     

温室栽培对软枣猕猴桃叶片形态及叶绿素荧光特性的影响

【目的】深入研究温室栽培条件下软枣猕猴桃叶片的形态与叶绿素荧光特性,探明温室与露地栽培环境下叶片光形态建成的差异。【方法】以软枣猕猴桃品种‘佳绿’和‘魁绿’的5年生植株为试材,测定温室及露地栽培条件下不同叶龄叶片的叶绿素相对含量及叶绿素荧光参数,分析这些参数在温室与露地栽培条件下的差异。【结果】温室与露地栽培软枣猕猴桃的光形态建成均处于1~40 d叶龄间,不同栽培条件下的同一品种荧光特性趋于一致;花期后,不同栽培条件下的同一品种荧光特性差异较大。温室栽培的软枣猕猴桃叶片叶面积较大,叶绿素b含量较高,趋于阴生叶特性,以吸收光能为基础的性能指数等显著低于露地栽培,对光能的吸收捕获能力较强,但热耗散较高,用于电子传递的能量低于露地栽培,叶绿素荧光参数表现出对环境的适应性变化。【结论】软枣猕猴桃叶片的光形态建成时间为展叶后1~40 d,即在花期之前完成,不同栽培环境无明显差异;温室栽培软枣猕猴桃叶片的光形态建成与露地栽培具显著差异,叶面积明显增大;温室栽培在一定程度上改变了叶片的叶绿素荧光特性,降低了光合性能。     

Photosynthetic acclimation of Chlorella saccharophila to heat stress

Photosynthesis is one of the most important metabolic processes of algae; which is altered as a stress response. During mass cultivation of algae, temperature rise and high light are major factors that affect biomass productivity. High temperature affects photosystem II (PSII) complex irreversibly, damaging intermolecular interactions in it. However, the impact of high temperature on photosynthesis is highly variable among different algal species, depending on the prior acclimation to environmental conditions they were exposed to. The acclimation plays an important role in combating high temperature stress via regulation of photosynthetic responses. Chlorophyll a fluorescence is a highly sensitive, non‐destructive and reliable tool for such measurements of photosynthetic parameters, which provides information about algal photosynthetic performance under given conditions. To understand the effect of heat stress on the responses of high light acclimated alga Chlorella saccharophila, chlorophyll a fluorescence transients were measured after heat exposure at 40°C. Our study demonstrates that rise in temperature for short duration; during open field cultivation reversibly affects the efficiency of PSII in light acclimated alga C. saccharophila. The effects of heat stress on chlorophyll a fluorescence in this alga, grown under high light (max‐1600 μmol photons m^?2 s^?1) are presented here; they are used to infer changes in photosynthetic process during its exposure to heat, as well as their recovery after 72 h. We speculate that heat resistance may have been acquired due to prior exposures to high light.     

NONDESTRUCTIVE TRACING OF MIGRATORY RHYTHMS OF INTERTIDAL BENTHIC MICROALGAE USING IN VIVO CHLOROPHYLL A FLUORESCENCE1,2

In vivo chlorophyll (Chl) a fluorescence was measured in undisturbed intertidal sediments with the purpose of tracing the vertical migratory rhythms of benthic microalgae. A pulse amplitude fluorometer, an instrument which does not require physical contact with the sample, was used, thus allowing successive measurements to be taken on the same sample without causing any type of disturbance to the sediment structure. The basis of the method is the possibility to detect changes in the Chl a concentration near the sediment surface caused by the vertical movement of the microalgae. This requires the verification of two conditions: the possibility to follow changes in the sediment Chl a content from fluorescence intensity, and a sediment photic depth smaller than the vertical distances covered by the moving microalgae. Both conditions were experimentally verified in intertidal muddy sediments of the Tagus estuary, Portugal. In vivo fluorescence was shown to vary linearly with the sediment Chl a content, and the sediment photic depth was estimated to reach 0.27 mm, a value clearly smaller than the reported depths for microalgal migrations. Sediment samples kept under in situ conditions exhibited large hourly Variations (over 400%) in the Chl a fluorescence intensity, which were closely synchronized with the daytime periods of emersion. The rhythmic fluctuations in Chl a fluorescence were confirmed further to represent microalgal migration by (1) its endogenous nature (fluorescence continued to follow diurnal and tidal cycles after removal of environmental stimuli), (2) its dependence on the vertical distribution of the microalgal population within the sediment (vertically homogenized samples failed to display fluorescence variations), and (3) the lack of significant temperature and light effects on the fluorescence emission under in situ conditions (tested in three species representative of the main groups found in the studied microphytobenthic communities—the diatom Phaeodactylum tricornutum (Böhlin), the cyanobacterium Spirulina maxima (Setch. et Gard.), and the euglenophyte Euglena granulata (Klebs) Lemm.). The results obtained indicate that, in spite of the potential concurrent effects of factors other than the Chl a concentration on the fluorescence intensity, in vivo Chl a fluorescence can be used to trace nondestructively the migratory behavior of benthic microalgae.     

Advancement of the cultivation and upscaling of photoautotrophic suspension cultures using <Emphasis Type="Italic">Chenopodium rubrum</Emphasis> as a case study

Photoautotrophic (PA) suspension cultures combine the advantages of cell suspensions with carbon autotrophy and have been used for various applications including studies on photosynthesis, sugar signal transduction, herbicide action, and stress responses. A major practical drawback is the requirement for elevated CO₂, which is typically generated by a buffer system in two-tier flasks that need to be custom made and require time-consuming handling. In this study, we substantially simplified and improved the cultivation of a PA culture of Chenopodium rubrum as a case study in Erlenmeyer flasks shaken in a CO₂ enriched photoincubator. Growth rates and photosynthetic activity were found to be comparable to those in two-tier flasks but with the advantage of constant CO₂ level throughout the cultivation. In addition, it was possible to establish the cultivation in a commercial laboratory-scale photobioreactor with various options to control and continuously measure the culture conditions and regimes and assess the physiological status. Although the relative biomass yield and photosynthetic performance of the batch cultures was not fully reached, the continuous cultivation system provides a good basis for future scale-up if larger amounts of biomass are needed or to impose specific cultivation regimes in combination with comprehensive online monitoring. The different improvements should contribute to the more widespread use of higher plant PA cultures and also facilitate the cultivation of microalgae.