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Technologies for Separation and Drying of Algal Biomass for Varied Applications
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
Julio Cesar de Carvalho, Eduardo Bittencourt Sydney, Paulo Cesar de Souza Kirnev, Adriane Bianchi Pedroni Medeiros, Carlos Ricardo Soccol
The recovery of microalgal biomass from low concentration suspensions is essential for processing into biomass and value-added products. Typical concentrations of commercial autotrophic microalgal cultures are 2–5 g/L. While mixotrophic and heterotrophic cultures may reach higher concentrations, the autotrophic cultures are more common, and their concentration usually cannot be high to avoid self-shadowing. Therefore, concentrating the cultures post-harvest is necessary to reduce volumes, thus for lowering energy requirements for other operations downstream. Microalgal biomass processing depends on its final use, but drying may be useful both for stabilization (e.g. for food and feed microalgae) and for further processing (e.g. biomass for lipid extraction).
Biogeneration of Volatile Organic Compounds in Microalgae-Based Systems
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
Pricila Nass Pinheiro, Karem Rodrigues Vieira, Andriéli Borges Santos, Eduardo Jacob-Lopes, Leila Queiroz Zepka
Some microalgae are mixotrophic and can simultaneously drive phototrophy and heterotrophy to utilize both inorganic (CO2) and organic carbon substrates, thus leading to an additive or synergistic effect of the two processes that enhance the productivity of biomass and consequently a production of volatile compounds (Bhatnagar et al. 2011). CO2 is fixed through photosynthesis, which is influenced by illumination, while organic compounds are assimilated through aerobic respiration, which is affected by the availability of organic carbon. Several species are able to switch between photoautotrophic and heterotrophic growth (Perez-Garcia and Bashan 2015).
Brevetoxin
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
While about half of living dinoflagellate species are autotrophs possessing chloroplasts, the other half are nonphotosynthesizing heterotrophs. In addition, some dinoflagellate species are mixotrophic, combining photosynthesis with phagotrophy (i.e., ingestion of prey such as other protozoa). Some dinoflagellates produce resting stages, called dinoflagellate cysts or dinocysts, as part of their life cycles. Further, dinoflagellate species K. brevis, K. mikimotoi, and Karlodinium micrum have acquired fucoxanthin pigments through endosymbiosis.
Current advances in the algae-made biopharmaceuticals field
Published in Expert Opinion on Biological Therapy, 2020
Sergio Rosales-Mendoza, Karla I. Solís-Andrade, Verónica A. Márquez-Escobar, Omar González-Ortega, Bernardo Bañuelos-Hernandez
The group headed by Mayfield is performing seminal studies on the large scale production of algae-made biopharmaceuticals. Bovine Milk Amyloid A (MAA) has been produced in C. reinhardtii grown under greenhouse conditions using 100-L plastic bags; leading to concentrations up to 2.27 mg∙L−1 of culture (1.39% of TSP), nonetheless these concentrations varied depending on the differential light irradiation caused by the position of the bags in the greenhouse [46]. Some authors have focused on optimizing culture light conditions to enhance protein and biomass yields. Carrera-Pacheco et al. [62] reported the effect of continuous light versus light/dark cycles; as well as light intensity on the expression of two recombinant proteins: GFP and a bacterial lysin-GFP fusion protein (GFP-PlyGBS). Optimized protein production conditions were determined for photoautotrophic, mixotrophic, and heterotrophic conditions. Protein yields were influenced by the light period (6–24 h∙d−1), light intensity (0–450 μE∙m−2⋅s−1), and trophic condition. Heterotrophic conditions showed lower yields of both recombinant proteins due to reduced growth rates, despite having high protein accumulation per cell. Mixotrophic conditions exhibited the highest yields for GFP (4 mg∙L−1·d−1) under constant light at 35 μE∙m−2⋅s−1 and GFP-PlyGBS (0.4 mg∙L−1·d−1) under a light period of 15 h∙d−1 and 35 μE∙m-2⋅s−1. For GFP-PlyGBS the maximum increase in cellular protein accumulation was ~24-fold and ~10-fold higher in total protein yield when compared to constant light conditions (~200 μE∙m-2⋅s−1). The highest yields under photoautotrophic conditions were obtained under a 9 h∙d−1 light period, with a GFP yield of 1.2 mg·L−1·d−1 and a GFP-PlyGBS yield of 0.42 mg·L−1·d−1. This represented a ~ 5-fold increase in cellular protein accumulation for GFP-PlyGBS in comparison to constant light conditions (~200 μE∙m-2⋅s−1). This report highlights that, besides genetic engineering approaches, the upstream processing is critical to enhance productivity. Similarly, some authors have proposed using Chlorella sorokiniana UTEX 1230 as model; using mixotrophic conditions and a fed-batch strategy to increase biomass productivity. A 3-fold increase in biomass yield was observed when mixotrophic conditions were applied, whereas the fed-batch approach increased the yield by 50% [63].