An algal cyclostat with computer-controlled dynamic light regime

Abstract

The aim of this paper is to provide detailed information concerning the hardware and software needed to design and construct a system for the continuous growth of algae, employing a computer-controlled variable dynamic light regime. The light intensity is controlled by adjusting the angular displacement of slats of a Venetian blind with the help of a stepper motor. The software developed allows the simulation of nature-related light flux regimes occurring in stratified water columns, mixed water columns with optically clear water, and mixed water columns with optically dense water. The light period, circulation time and attenuation coefficient can be chosen freely. Different light regimes with equal total light doses can be generated with the help of mathematical equations developed for this purpose. The software developed is of the Terminate and Stay Resident (TSR) type and operates in the background, thus allowing the computer to be used for other tasks. The system can be used to investigate algal growth and photosynthesis in relation to a dynamic light regime. The characteristics of the light regimes applied during the Vth GAP workshop are presented. The results of these experiments will be described in subsequent papers.

The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae

“…S. costatum (clone 'Banyuls' e Laboratoire Arago Collection, Banyulssur-Mer, France) and C. meneghiniana were grown in a modified artificial seawater f/2 medium [60]. The continuous growth of S. costatum at 20 C was performed in a cyclostat [61] under either block light conditions (BL) at a PFD of 60 mmol photons m À2 s À1 or under a computer-controlled simulation of a fluctuating light climate (FL; maximum PFD 950 mmol photons m À2 s À1 ) as described by…”

Different phycobilin antenna organisations affect the balance between light use and growth rate in the cyanobacterium Microcystis aeruginosa and in the cryptophyte Cryptomonas ovata

“…For C. ovata, the medium was additionally enriched with vitamin solution A (Provasoli et al 1957) and TRIS buffer (10 mM final concentration) and adjusted to pH 7.4. A cyclostat (according to Kroon et al 1992) with computer-controlled regulation of light climate was used for the algal culture. The daily mean Chla concentration was 0.7 mg l -1 (±0.04 mg l -1 ) and 1.5 mg l -1 (±0.04 mg l -1 ) for M. aeruginosa and C. ovata, respectively.…”

Balancing the energy flow from captured light to biomass under fluctuating light conditions

“…Algal culture and light climates were performed in a cyclostat (according to Kroon et al ., 1992a) with computer-controlled regulation of light supply and at a Chl a concentration of 2 mg l − 1 ( ± 0.2). In addition, with the rectangular culture vessel (237 × 450 mm, 30 mm depth) the self-shading effects were kept to a minimum.…”