A pilot-scale floating closed culture system for the multicellular cyanobacterium Arthrospira platensis NIES-39

Biomanufacturing of glycosylated antibodies: Challenges, solutions, and future prospects

Traditionally, recombinant protein production has been done in several expression hosts of bacteria, fungi, and majorly CHO (Chinese Hamster Ovary) cells; few have high production costs and are susceptible to harmful toxin contamination. Green algae have the potential to produce recombinant proteins in a more sustainable manner. Microalgal diversity leads to offer excellent opportunities to produce glycosylated antibodies. An antibody with humanized glycans plays a crucial role in cellular communication that works to regulate cells and molecules, to control disease, and to stimulate immunity. Therefore, it becomes necessary to understand the role of abiotic factors (light, temperature, pH, etc.) in the production of bioactive molecules and molecular mechanisms of product synthesis from microalgae which would lead to harnessing the potential of algal bio-refinery. However, the potential of microalgae as the source of bio-refinery has been less explored. In the present review, omics approaches for microalgal engineering, methods of humanized glycoproteins production focusing majorly on N-glycosylation pathways, light-based regulation of glycosylation machinery, and production of antibodies with humanized glycans in microalgae with a major emphasis on modulation of post-translation machinery of microalgae which might play a role in better understanding of microalgal potential as a source for antibody production along with future perspectives.

Integrating wind-driven agitating blade into a floating photobioreactor to enhance fluid mixing and microalgae growth

Aiming at optimizing the poor fluid mixing state in the traditional horizontal floating photobioreactors and reducing the high energy consumption and operational cost induced by electric-driven mixing, a novel floating photobioreactor with an embedded wind-driven agitating blade (WDAB-FPBR) was proposed in this study, which can effectively utilize both wind and wave energy for fluid mixing. The results show that the selected wind-driven agitating blade contributed to a decrement of 75.3% in mixing time and an increment of 87.5% in mass transfer coefficient, and meanwhile strengthened the fluid velocity along the light gradient. Owing to the enhanced fluid flow and mixing properties, an even distribution of algae cells was achieved in the WDAB floating photobioreactor, which resulted in an improvement of 140% in the photosynthesis efficiency of microalgae. From this, the biomass yield and carbon removal ratio showed an increment of 88.9% and 73.9%, respectively.

Innovative application of brackish groundwater without the addition of nutrients in the cultivation of Spirulina and Chlorella for carbohydrate and lipid production

Brackish groundwater is promising for the cultivation of economically important microalgae; however, its effects have been evaluated only after nutrient supplementation. In this study, 100% brackish groundwater was evaluated as a culture medium for Spirulina sp. (BGWS) and Chlorella fusca (BGWC). In addition, the effects of supplementation with 25% of the nutrients from Zarrouk (BGWS25) and BG-11 (BGWC25) culture media were evaluated. BGWS and BGWC increased the concentration (68.1% w w^-1) and productivity of carbohydrate (35.3 mg L^-1 d^-1) in Spirulina sp. and increased the concentration (56.4% w w^-1) and productivity (13.5 mg L^-1 d^-1) of lipids in C. fusca biomass, when compared to that in the respective controls. The use of brackish groundwater as the sole culture medium is an innovative alternative for the economic production of biomass rich in carbohydrates and lipids. This has potential applications for biofuel production.

Enhanced Arthrospira platensis Biomass Production Combined with Anaerobic Cattle Wastewater Bioremediation

Microalgae biomasses offer important benefits regarding macromolecules that serve as promising raw materials for sustainable production. In the present study, the microalgae Arthrospira platensis DHR 20 was cultivated in horizontal photobioreactors (HPBR), with and without temperature control, in batch mode (6 to 7 days), with anaerobically digested cattle wastewater (ACWW) as substrate. High dry biomass concentrations were observed (6.3-7.15 g L^-1). Volumetric protein, carbohydrate, and lipid productivities were 0.299, 0.135, and 0.108 g L^-1 day^-1, respectively. Promising lipid productivities per area were estimated between 22.257 and 39.446 L ha^-1 year^-1. High CO₂ bio-fixation rates were recorded (875.6-1051 mg L^-1 day^-1), indicating the relevant potential of the studied microalgae to mitigate atmospheric pollution. Carbon concentrations in biomass ranged between 41.8 and 43.6%. ACWW bioremediation was satisfactory, with BOD₅ and COD removal efficiencies of 72.2-82.6% and 63.3-73.6%. Maximum values of 100, 95.5, 92.4, 80, 98, and 94% were achieved concerning the removal of NH₄ ⁺, NO₃ ^-, P_t, SO₄ ^2-, Zn, and Cu, respectively. Total and thermotolerant coliform removals reached 99-99.7% and 99.7-99.9%. This microalgae-mediated process is, thus, promising for ACWW bioremediation and valuation, producing a microalgae biomass rich in macromolecules that can be used to obtain friendly bio-based products and bioenergy.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12155-021-10258-4.

Differential response of photosynthetic apparatus towards alkaline pH treatment in NIES-39 and PCC 7345 strains of Arthrospira platensis

Alkaline stress is one of the severe abiotic stresses, which is not well studied so far, especially among cyanobacteria. To affirm the characteristics of alkaline stress and the subsequent adaptive responses in Arthrospira platensis NIES-39 and Arthrospira platensis PCC 7345, photosynthetic pigments, spectral properties of thylakoids, PSII and PSI activities, and pigment-protein profiles of thylakoids under different pH regimes were examined. The accessory pigments showed a pH-mediated sensitivity. The pigment-protein complexes of thylakoids are also affected, resulting in the altered fluorescence emission profile. At pH 11, a possible shift of the PBsome antenna complex from PSII to PSI is observed. PSII reaction center is found to be more susceptible to alkaline stress in comparison to the PSI. In Arthrospira platensis NIES-39 at pH 11, a drop of 68% in the oxygen evolution with a significant increase of PSI activity by 114% is recorded within 24 h of pH treatment. Alterations in the cellular ultrastructure of Arthrospira platensis NIES-39 at pH 11 were observed, along with the increased number of plastoglobules attached with the thylakoid membranes. Arthrospira platensis NIES-39 is more adaptable to pH variation than Arthrospira platensis PCC 7345.

Conversion of NaHCO3 to Na2 CO3 with a growth of Arthrospira platensis cells in 660 m2 raceway ponds with a CO2 bicarbonation absorber

The weight ratio of Na2 CO3 /NaHCO3 was investigated in order to improve microalgal productivity in large-scale industrial operations by converting NaHCO3 to Na2 CO3 with a growth of Arthrospira platensis cells in 660 m2 raceway ponds. Two microalgal cultivation systems with a NaHCO3 by-product (SPBP) and a CO2 bicarbonation absorber (CBAP) were firstly thoroughly introduced. There was a 13.3% decrease in the initial weight ratio of Na2 CO3 /NaHCO3 resulting in a 25.3% increase in the biomass growth rate with CBAP, compared to that of SPBP. Increased sunlight intensity, solution temperature and pH all resulted in both a higher HCO 3 - absorbance and CO 3 2 - release, thereby increasing the weight ratio of Na2 CO3 /NaHCO3 during the growth of A. platensis. The biomass growth rate was peaked at 39.9 g m-2  day-1 when the weight ratio of Na2 CO3 /NaHCO3 was 3.7. Correspondingly, the cell pigments (chlorophyll a and carotenoid) and trichome size (helix pitch and trichome length) reached to a maximum state of 8.47 mg l-1 , 762 μg l-1 , 57 and 613 μm under the CBAP system.

Quantum yield alterations due to the static magnetic fields action on Arthrospira platensis SAG 21.99: Evaluation of photosystem activity

Static magnetic fields (SMF) influence the metabolism of microorganisms, however, there is no knowledge explaining how SMF act in cells. This study aimed at evaluating the SMF (30 mT) effect on photosynthetic performance, growth and biomass composition of the cyanobacterium Arthrospira platensis SAG 21.99. A. platensis was cultivated under 30 mT applied for 1 h d^-1 and 24 h for 10 d in glass bottles. SMF in both conditions increased cellular growth, achieving a 30% higher biomass concentration. SMF applied for 1 h d^-1 increased the pigments and carbohydrate content. The quantum yield was used as an indicator of the photosystem II (PSII) activity and was shown to have been positively affected. SMF for 1 h d^-1 had a significant effect on the OJIP curves. This is the first study that evaluated the photosynthetic activity in cyanobacteria cultures under SMF action.

Promoting helix pitch and trichome length to improve biomass harvesting efficiency and carbon dioxide fixation rate by Spirulina sp. in 660 m2 raceway ponds under purified carbon dioxide from a coal chemical flue gas

The helix pitch and trichome length of Spirulina sp. were promoted to improve the biomass harvesting efficiency and CO₂ fixation rate in 660 m² raceway ponds aerated with food-grade CO₂ purified from a coal chemical flue gas. The CO₂ fixation rate was improved with increased trichome length of the Spirulina sp. in a raceway pond with double paddlewheels, baffles, and CO₂ aerators (DBA raceway pond). The trichome length has increased by 33.3 μm, and CO₂ fixation rate has increased by 42.3% and peaked to 51.3 g/m²/d in a DBA raceway pond. Biomass harvesting efficiency was increased with increased helix pitch. When the day-average greenhouse temperature was 33 °C and day-average sunlight intensity was 72,100 lu×, the helix pitch of Spirulina sp. was increased to 56.2 μm. Hence the biomass harvesting efficiency was maximized to 75.6% and biomass actual yield was increased to 35.9 kg in a DBA raceway pond.

Simbiotics: A Multiscale Integrative Platform for 3D Modeling of Bacterial Populations

Simbiotics is a spatially explicit multiscale modeling platform for the design, simulation and analysis of bacterial populations. Systems ranging from planktonic cells and colonies, to biofilm formation and development may be modeled. Representation of biological systems in Simbiotics is flexible, and user-defined processes may be in a variety of forms depending on desired model abstraction. Simbiotics provides a library of modules such as cell geometries, physical force dynamics, genetic circuits, metabolic pathways, chemical diffusion and cell interactions. Model defined processes are integrated and scheduled for parallel multithread and multi-CPU execution. A virtual lab provides the modeler with analysis modules and some simulated lab equipment, enabling automation of sample interaction and data collection. An extendable and modular framework allows for the platform to be updated as novel models of bacteria are developed, coupled with an intuitive user interface to allow for model definitions with minimal programming experience. Simbiotics can integrate existing standards such as SBML, and process microscopy images to initialize the 3D spatial configuration of bacteria consortia. Two case studies, used to illustrate the platform flexibility, focus on the physical properties of the biosystems modeled. These pilot case studies demonstrate Simbiotics versatility in modeling and analysis of natural systems and as a CAD tool for synthetic biology.