Algal Research

Journal: Algal Research

Publisher

Elsevier

ISSN

2211-9264

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Publications 1 - 8 of 8

First developments towards closing the nutrient cycle in a biofuel production process
Bagnoud-Velásquez, M.; Schmid-Staiger, U.; Peng, G.; et al. (2015)
Algal Research
Growth kinetic model of Chlorella vulgaris in a dark biogas slurry culture system based on a light attenuation model
Liu, Xueyan; Chen, Chaorui; Lu, Haifeng; et al. (2025)
Algal Research
Using biogas slurry to culture microalgae can realize pollutants transformation into useful biomass, it has been attracted by the whole recycling-oriented society and low-carbon effect. However, the dark color of biogas slurry caused light attenuation, which weakened the light provision for microalgal growth. In this work, the microalgal growth models of dark color biogas slurry-microalgae cultivation system (DBS-M) were established. Results showed that chroma can be introduced in Lambert-Beer Law for describing the rules of light condition changes. While microalgal cells concentration contribute more light attenuation effect compared with chroma: the degree of light attenuation caused by 1000 Hazen's dark biogas slurry is equivalent to that by 0.18gL⁻¹ biomass. The dynamic changes of biomass concentration and the light attenuation model in DBS-M can also be combined with average light intensity to form the optimal Pearl-Monod (PM) model for predicting microalgal growth, which can respond to the changes of optical path (different photobioreactors) and biomass concentration in real production system. This further improves the accuracy and universality of the models. According to the above models, 5 cm is desirable PBRs optical path. Under this condition, with the initial biomass was below 0.4gL⁻¹ and I0 was 240–480 μmolm⁻²s⁻¹, μ of C. vulgaris reached above 1.0d⁻¹. Finally, a semi-continuous culture strategy for C. vulgaris growth in biogas slurry and an average daily yield (P) model was established. According to the model, the highest P reached 0.186 g L⁻¹d⁻¹ when the daily initial biomass was maintained at 0.375 g L⁻¹d⁻¹ under the semi-continuous culture, which was 23.75 % higher than that of the sequencing batch. This work might be helpful for the operation of dark color biogas slurry-microalgae cultivation system in large scale in the future.
Chlorella vulgaris in a heterotrophic bioprocess: study of the lipid bioaccessibility and oxidative stability
Canelli, Greta; Neutsch, Lukas; Carpine, Roberta; et al. (2020)
Algal Research
Microalgal biomass is an emerging source of several health-related compounds, including polyunsaturated fatty acids. Herein, Chlorella vulgaris was cultivated heterotrophically in a 16-L stirred tank bioreactor. The lipid oxidative stability and lipid bioaccessibility of the biomass harvested during the exponential and stationary phases were evaluated. The biomass harvested during the stationary phase showed lower lipid oxidation than that harvested during the exponential phase, likely due to the higher content of antioxidants in the former. In both biomasses, the hexanal and propanal profiles showed only moderate increase over 12 weeks of storage at 40 °C, indicating good oxidative stability. Lipid bioaccessibility measured in an infant in vitro model was 0.66% ± 0.16% and 2.41% ± 0.61% for the biomass harvested during the exponential and late stationary phases, respectively. This study indicates that C. vulgaris biomass can be considered as a stable and nutritious (optimal ω3:ω6 profile) source of essential fatty acids. Our results suggested that regarding lipid stability and bioaccessibility, harvesting during stationary phase could be preferred choice. In general, treatment of the biomass to increase lipid bioaccessibility should be investigated.
Proteomic characterization of pilot scale hot-water extracts from the industrial carrageenan red seaweed Eucheuma denticulatum
Gregersen, Simon; Pertseva, Margarita; Marcatili, Paolo; et al. (2022)
Algal Research
Seaweeds have a long history as a resource for polysaccharides/hydrocolloids extraction for use in the food industry due to their functionality as stabilizing agents. In addition to the carbohydrate content, seaweeds also contains a significant amount of protein, which may find application in food and feed. Here, we present a novel combination of transcriptomics, proteomics, and bioinformatics to determine the protein composition in two pilot-scale extracts from Eucheuma denticilatum (Spinosum) obtained via hot-water extraction. Although the quality of extracted protein appeared quite poor based on SDS-PAGE analysis, extracts were characterized by qualitative and quantitative proteomics using LC-MS/MS and a de-novo transcriptome assembly for construction of a suitable protein database. A novel concept of length-normalization for relative quantification of sub-optimal protein extracts with partial, non-specific digestion is introduced and validated against conventional methods for relative quantification of proteins. Despite a limited number of protein identifications due to poor protein quality, our data suggest that the majority of quantified protein in the extracts (>75%) is constituted by merely three previously uncharacterized proteins. Putative subcellular localization for the quantified proteins was determined by bioinformatic prediction using several predictors, and by correlating with the expected copy number from the transcriptome analysis, we find that the extracts appear highly enriched in extracellular proteins. This implies that the extraction method used predominantly extracts extracellular proteins, and thus appear ineffective for cellular disruption and subsequent release of intracellular proteins. Nevertheless, the highly abundant proteins may be potential substrates for targeted hydrolysis and release of bioactive peptides. Ultimately, this study highlight the potential of quantitative proteomics for characterization of alternative protein sources intended for use in foods and evaluating protein extraction process efficiency through novel combinations with bioinformatic analysis.
Wirelessly powered submerged-light illuminated photobioreactors for efficient microalgae cultivation
Murray, Alexandra Marie; Fotidis, Ioannis A.; Isenschmid, Alex; et al. (2017)
Algal Research
Microfiltration of Microalgae Biomolecules: Impact of Pulsed Electric Fields and High-Pressure Homogenization on Single-Cell Protein Recovery and Membrane Fouling
Perez Simba, Byron; Li, Zhao; Haberkorn, Iris; et al. (2025)
Algal Research
This study investigated the separation of single-cell proteins from disrupted Auxenochlorella protothecoides microalgae using microfiltration. The microalgae were heterotrophically cultivated and subjected to two cell disruption methods, high-pressure homogenization (HPH) and pulsed electric field with incubation (PEF + inc), and stored at −20 °C. The impact of HPH and PEF + inc on the microfiltration performance of thawed samples was assessed. HPH treatment resulted in complete cell lysis, releasing a heterogeneous mixture of intracellular compounds. This, potentially combined with freezing effects, led to rapid membrane fouling and a 70 % decline in the permeate flux, finally stabilizing at 15 L m−2 h−1. In contrast, PEF + inc preserved cell integrity and particle size even after freezing, liberating mainly soluble compounds. This resulted in a more porous cake layer and a limited decline in the permeate flux, which stabilized at 24 L m−2 h−1. Additionally, higher protein transmission rates were achieved with PEF + inc (141.75 g m−2 h−1) than with HPH (54.53 g m−2 h−1) and was 5.6 times more energy efficient. The cake layer formed by the HPH-treated samples had a higher resistance owing to smaller apparent pores and increased interaction with permeating proteins, which hindered protein transmission. These findings demonstrate that cell disruption methods can significantly influence downstream protein recovery efficiency and energy consumption. PEF + inc shows great potential as an energy-efficient bioprocessing method for microalgae biorefineries.
Reversible electropermeabilization of Auxenochlorella protothecoides microalgae: tracking mass transfer and membrane resealing dynamics induced by pulsed electric fields
Perez Simba, Byron; Weber, Nicola; Haberkorn, Iris; et al. (2025)
Algal Research
Pulsed Electric Field (PEF) treatment is an emerging technology that enhances mass transfer by inducing cell permeabilization, offering great potential in microalgae bioprocessing. While irreversible permeabilization for extraction has been extensively studied, reversible permeabilization remains largely unexplored for most microalgae species, thus limiting its application in processes requiring viable cells, such as cyclic extraction, gene delivery, and cell fortification. This study investigated how electric field strength and split pulse configuration, either a single long pulse or multiple shorter pulses, affect the reversible electropermeabilization of Auxenochlorella protothecoides. The uptake of the cell membrane-impermeable stain Sytox Green™ was used to assess cell permeabilization, while protein extraction served as a mass transfer indicator. Results showed that a split pulse configuration (2 × 50 μs or 5 × 20 μs pulses at 15 kV cm$^{-1}$) increased the relative fluorescence intensity fivefold compared with a single long pulse, with only a 12 % increase in energy input. The split pulse approach kept the cells permeable for over 10 min, enabling 38 % more protein extraction with 41 % less energy than a single pulse at 20 kV cm$^{−1}$, but this higher degree of permeabilization compromised cell viability, killing around 70 % of the cells and delaying regrowth during the first 48 h, thereby hindering suitability for live-cell applications. For the first time, the resistance of A. protothecoides to high electric fields has been investigated, e.g., with a single pulse of 15 kV cm$^{−1}$ permeabilizing the cells for at least 5 min while maintaining good resealing and survival rates comparable to the untreated control. These findings offer valuable insights into maximizing reversible permeabilization, mass transfer, and cell survival in microalgae while minimizing energy consumption in PEF processing.
Influence of biodiversity, biochemical composition, and species identity on the quality of biomass and biocrude oil produced via hydrothermal liquefaction
Hietala, David C.; Koss, Cristina K.; Narwani, Anita; et al. (2017)
Algal Research
We compared several measures of quality for biomass and biocrude oil produced via hydrothermal liquefaction for monocultures and polycultures of the freshwater microalgae Ankistrodesmus falcatus, Chlorella sorokiniana, Pediastrum duplex, Scenedesmus acuminatus, Scenedesmus ecornis, and Selenastrum capricornutum. On average, the 2-species cultures provided product quality comparable to that of the monocultures, while that of the average 4- and 6-species polycultures was lower. No single monoculture or polyculture performed the best with respect to all quality metrics considered, including biomass fatty acid content and biocrude elemental content and higher heating value. However, for each measure of quality, some polycultures did outperform or match the performance of the best monoculture for each respective metric. Numerous polycultures performed outside the range of product quality exhibited by their constituent species (transgressive overyielding), and polycultures with P. duplex did so to the greatest extent. Microalgal biochemical composition was correlated with biocrude properties, however including species identity as an additional correlation variable further explained the observed variation. Finally, we highlight several polycultures that offer potentially compelling trade-offs between product quantity and quality compared to the most productive monoculture.

Publications 1 - 8 of 8

Journal: Algal Research

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