Investigation of Cell Growth and Chlorophyll a Content of the Coccolithophorid Alga Emiliania huxleyi by Using Simple Bench-Top Flow Cytometry

The coccolithophorid alga Emiliania huxleyi produces micro-structured calcite particles, which are called coccoliths. Due to their unique and sophisticated structure, coccoliths are highly promising for different industrial applications, such as paper manufacturing, color and lacquer preparation. The mass production of coccoliths requires the evaluation of optimum cultivation conditions. This study investigates the impact of varying irradiance (10-1500 µmol m-² s-1) on growth and chlorophyll a content of two calcifying strains CCMP371 and RCC1216 as well as on the non-calcifying strain RCC1217 (haploid form of RCC1217). The light kinetics contradicts the popular opinion, that E. huxleyi is an extraordinarily light tolerating alga in general. Photoinhibition was already observed at irradiance >500 µmol m-2 s-1 in the case of the calcifying strains. Furthermore, light requirements to grow at maximum growth rate, as well as thresholds towards photoinhibition were considerably different between calcifying and non-calcifying strains. The haplont required significantly higher irradiance to reach maximum µspec (>200 µmol m-2 s-1), while being much more tolerant to towards photoinhibition, which occurred not until 800 µmol m-2 s-1. Furthermore, a novel method was proposed to allow for the estimation of chlorophyll a content from flow cytometry data. By comprising an Advanced Fluorescence Ratio (AFLR), which considers culture heterogeneity, this method enables for simple chlorophyll a estimation also in older cultures of calcifying Emiliania huxleyi, which tend to build agglomerates

Medium optimization for biomass production of three peat moss (Sphagnum L.) species using fractional factorial design and response surface methodology

Peat moss (Sphagnum) biomass is a promising bioresource of renewable material to substitute peat in growing media. For sustainable production on a large scale, the productivity of Sphagnum mosses has to be increased by optimizing culture conditions. Optimization was achieved using experimental design to determine concentrations of eight factors leading to highest biomass yield. We improved an established Sphagnum medium by reducing the concentrations of NH$_{4}$NO$_{3}$, KH$_{2}$PO$_{4}$, KCl, MgSO$_{4}$, Ca(NO$_{3}$)$_{2}$, FeSO$_{4}$ and a microelement solution up to 50%. Together with sucrose concentrations of 16 g L$^{-1}$ for Sphagnum fuscum and 20 g L$^{-1}$ for Sphagnum palustre and Sphagnum squarrosum, moss productivities were enhanced for all tested species in shake flasks. Further upscaling to 5 L photobioreactors increased the biomass yield: 15 g freshweight resulted in about 630 g for S. fuscum (50-fold), 580 g for S. palustre (40-fold) and 400 g for S. squarrosum (25-fold) in 24 days

Comprehensive Computational Model for Coupled Fluid Flow, Mass Transfer, and Light Supply in Tubular Photobioreactors Equipped with Glass Sponges

The design and optimization of photobioreactor(s) (PBR) benefit from the development of robust and quantitatively accurate computational fluid dynamics (CFD) models, which incorporate the complex interplay of fundamental phenomena. In the present work, we propose a comprehensive computational model for tubular photobioreactors equipped with glass sponges. The simulation model requires a minimum of at least three submodels for hydrodynamics, light supply, and biomass kinetics, respectively. First, by modeling the hydrodynamics, the light–dark cycles can be detected and the mixing characteristics of the flow (besides the mass transport) can be analyzed. Second, the radiative transport model is deployed to predict the local light intensities according to the wavelength of the light and scattering characteristics of the culture. The third submodel implements the biomass growth kinetic by coupling the local light intensities to hydrodynamic information of the CO2 concentration, which allows to predict the algal growth. In combination, the novel mesoscopic simulation model is applied to a tubular PBR with transparent walls and an internal sponge structure. We showcase the coupled simulation results and validate specific submodel outcomes by comparing the experiments. The overall flow velocity, light distribution, and light intensities for individual algae trajectories are extracted and discussed. Conclusively, such insights into complex hydrodynamics and homogeneous illumination are very promising for CFD-based optimization of PBR

Comprehensive Computational Model for Coupled Fluid Flow, Mass Transfer, and Light Supply in Tubular Photobioreactors Equipped with Glass Sponges

The design and optimization of photobioreactor(s) (PBR) benefit from the development of robust and quantitatively accurate computational fluid dynamics (CFD) models, which incorporate the complex interplay of fundamental phenomena. In the present work, we propose a comprehensive computational model for tubular photobioreactors equipped with glass sponges. The simulation model requires a minimum of at least three submodels for hydrodynamics, light supply, and biomass kinetics, respectively. First, by modeling the hydrodynamics, the light–dark cycles can be detected and the mixing characteristics of the flow (besides the mass transport) can be analyzed. Second, the radiative transport model is deployed to predict the local light intensities according to the wavelength of the light and scattering characteristics of the culture. The third submodel implements the biomass growth kinetic by coupling the local light intensities to hydrodynamic information of the CO2 concentration, which allows to predict the algal growth. In combination, the novel mesoscopic simulation model is applied to a tubular PBR with transparent walls and an internal sponge structure. We showcase the coupled simulation results and validate specific submodel outcomes by comparing the experiments. The overall flow velocity, light distribution, and light intensities for individual algae trajectories are extracted and discussed. Conclusively, such insights into complex hydrodynamics and homogeneous illumination are very promising for CFD-based optimization of PBR

Effect of Traditional Household Processes on Iron, Zinc and Copper Bioaccessibility in Black Bean (Phaseolus vulgaris L.)

Micronutrient deficiencies are a major public health problem. Beans are an important plant-based source of iron, zinc and copper, but their absorption is reduced in the presence of anti-nutrients such as phytates, polyphenols and tannins. Soaking and discarding the soaking water before cooking is unanimously recommended, but this can result in mineral loss. Data on the consequences for mineral bioaccessibility is still limited. This study aimed to evaluate iron, zinc and copper bioaccessibility in black beans cooked (regular pan, pressure cooker) with and without the soaking water. For that, three batches of black beans were investigated in triplicate, each split in nine parts (raw grains and four different household processes in duplicate) and analyzed by applying the quarter technique, resulting in a grand total of 164 samples. Minerals were quantified by ICP-MS (inductively coupled plasma mass spectrometry), myo-inositol phosphates (InsP5, InsP6) by HPLC (high-performance liquid chromatography) ion-pair chromatography, total polyphenols using Folin-Denis reagent and condensed tannins using Vanillin assay. Mineral bioaccessibility was determined by in vitro digestion and dialysis. All treatments resulted in a statistically significant reduction of total polyphenols (30%) and condensed tannins (20%). Only when discarding the soaking water a loss of iron (6%) and copper (30%) was observed, and InsP6 was slightly decreased (7%) in one treatment. The bioaccessibility of iron and zinc were low (about 0.2% iron and 35% zinc), but copper presented high bioaccessibility (about 70%). Cooking beans under pressure without discarding the soaking water resulted in the highest bioaccessibility levels among all household procedures. Discarding the soaking water before cooking did not improve the nutritional quality of the beans