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- Industrial production of Phaeodactylum tricornutum for CO2 mitigation: biomass productivity and photosynthetic efficiency using photobioreactors of different volumesPublication . Quelhas, Pedro M.; Trovao, Mafalda; Silva, Joana T.; Machado, Adriana; Santos, Tamara; Pereira, Hugo; Varela, João; Simoes, Manuel; Silva, Joana L.The photosynthetic efficiency (PE) and potential of Phaeodactylum tricornutum for CO2 mitigation in industrial tubular photobioreactors (PBRs) of different volumes were evaluated. A preliminary assay was performed at lab-scale to optimize the salt concentration of the culture medium. Interestingly, salinity did not affect the growth of P. tricornutum at concentrations of 2.5, 5, 10, and 20 g L-1. Higher volumetric productivities were achieved in the 2.5-m(3) tubular PBR (0.235 g L-1 day(-1)), followed by 35- and 10-m(3) PBRs. Maximum areal productivities corresponded to 48.5, 45.0, and 12.8 g m(-2) day(-1) for the 35-, 10-, and 2.5-m(3) PBRs, respectively. PE was thus higher in the 35- and 10-m(3) PBRs (2.21 and 2.08%, respectively). The 10- and 35-m(3) PBR showed CO2 mitigation efficiencies of 60 and 41%, respectively, of the CO2 introduced into the PBR, corresponding to 2.3 and 2.5 g of fixed CO2 per g of biomass. Overall, cultivation of P. tricornutum couples high PE and areal productivity when the industrial PBRs were used, particularly PBRs of larger volumes. This improved PE performance with larger PBR volumes strongly suggests that large-scale cultivation of this diatom holds great potential for industrial CO2 mitigation.
- Nutritional potential and toxicological evaluation of tetraselmis sp. CTP4 microalgal biomass produced in industrial photobioreactorsPublication . Pereira, Hugo; Silva, Joana; Santos, Tamara; Gangadhar, Katkam N.; Raposo, Ana; Nunes, Cláudia; Coimbra, Manuel A.; Gouveia, Luísa; Barreira, Luísa; Varela, JoãoCommercial production of microalgal biomass for food and feed is a recent worldwide trend. Although it is common to publish nutritional data for microalgae grown at the lab-scale, data about industrial strains cultivated in an industrial setting are scarce in the literature. Thus, here we present the nutritional composition and a microbiological and toxicological evaluation of Tetraselmis sp. CTP4 biomass, cultivated in 100-m3 photobioreactors at an industrial production facility (AlgaFarm). This microalga contained high amounts of protein (31.2 g/100 g), dietary fibres (24.6 g/100 g), digestible carbohydrates (18.1 g/100 g) and ashes (15.2 g/100 g), but low lipid content (7.04 g/100 g). The biomass displayed a balanced amount of essential amino acids, n-3 polyunsaturated fatty acids, and starch-like polysaccharides. Significant levels of chlorophyll (3.5 g/100 g), carotenoids (0.61 g/100 g), and vitamins (e.g., 79.2 mg ascorbic acid /100 g) were also found in the biomass. Conversely, pathogenic bacteria, heavy metals, cyanotoxins, mycotoxins, polycyclic aromatic hydrocarbons, and pesticides were absent. The biomass showed moderate antioxidant activity in several in vitro assays. Taken together, as the biomass produced has a balanced biochemical composition of macronutrients and (pro-)vitamins, lacking any toxic contaminants, these results suggest that this strain can be used for nutritional applications.
- Growth performance, biochemical composition and sedimentation velocity of Tetraselmis sp. CTP4 under different salinities using low-cost lab- and pilot-scale systemsPublication . Trovão, Mafalda; Pereira, Hugo; Silva, Joana; Páramo, Jaime; Quelhas, Pedro; Santos, Tamara; Silva, Joana T.; Machado, Adriana; Gouveia, Luísa; Barreira, Luísa; Varela, JoãoBiomass harvesting is one of the most expensive steps of the whole microalgal production pipeline. Therefore, the present work aimed to understand the effect of salinity on the growth performance, biochemical composition and sedimentation velocity of Tetraselmis sp. CTP4, in order to establish an effective low-cost pilot-scale harvesting system for this strain. At lab scale, similar growth performance was obtained in cultures grown at salinities of 5, 10 and 20 g L-1 NaCl. In addition, identical settling velocities (2.4-3.6 cm h-1) were observed on all salinities under study, regardless of the growth stage. However, higher salinities (20 g L-1) promoted a significant increase in lipid contents in this strain compared to when this microalga was cultivated at 5 or 10 g L-1 NaCl. At pilot-scale, cultures were cultivated semi-continuously in 2.5-m3 tubular photobioreactors, fed every four days, and stored in a 1-m3 harvesting tank. Upon a 24-hour settling step, natural sedimentation of the microalgal cells resulted in the removal of 93% of the culture medium in the form of a clear liquid containing only vestigial amounts of biomass (0.07 ± 0.02 g L-1 dry weight; DW). The remaining culture was recovered as a highly concentrated culture (19.53 ± 4.83 g L-1 DW) and wet microalgal paste (272.7 ± 18.5 g L-1 DW). Overall, this method provided an effective recovery of 97% of the total biomass, decreasing significantly the harvesting costs.
- Effect of light quality supplied by light emitting diodes (LEDs) on growth and biochemical profiles of Nannochloropsis oculata and Tetraselmis chuiiPublication . Schulze, Peter S.C.; Pereira, Hugo; Schueler, Lisa; Guerra, Rui Manuel Farinha das Neves; Barreira, Luísa; Perales, Jose A.; Varela, João; Santos, TamaraBiochemical components obtained by microalgal biomass can be induced by specific wavelengths and processed to high value food/feed supplements or pharma- and nutraceuticals. Two biotechnologically relevant microalgae, Nannochloropsis oculata and Tetraselmis chuii, were exposed to non-tailored LEDs light sources emitting either mono- or multichromatic light with low red but significant blue (<450 nm) photon content, or tailored light sources with high blue or high red photon emissions: fluorescent light (FL), di- or multichromatic LED mixes. Growth of N. oculata and T. chuii under tailored light resulted in a approximate to 24% increase of the average biomass productivity as compared to cultures lit by non-tailored light sources. FL induced the highest C:N ratios in both algae (N. oculata: 7.91 +/- 0.09 and T. chuii: 11.29 +/- 0.03), highest total lipid (48.37 +/- 1.07%) in N. oculata and carbohydrate (55.31 +/- 1.02%) in T. chuii biomass. Among non-tailored light sources, monochromatic LEDs with emission peaks 465, 630 and 660 nm induced a approximate to 29% increase of carbohydrates and a approximate to 20% decrease of protein levels as compared to LEDs peaking at 405 nm and cool-and warm white LEDs. In conclusion, as FL have low photon conversion efficiencies (PCE), particularly within the red wavelength range, LEDs emitting at the 390-450 and 630-690 nm wavebands should be combined for optimal carbon fixation, nitrogen and phosphate uptake. (C) 2016 Elsevier B.V. All rights reserved.
- Health promoting potential of herbal teas and tinctures from Artemisia campestris subsp maritima: from traditional remedies to prospective productsPublication . Pereira, Catarina; Barreira, Luísa; Bijttebier, Sebastiaan; Pieters, Luc; Marques, Catia; Santos, Tamara; Rodrigues, Maria Joao; Varela, João; Custodio, LuisaThis work explored the biotechnological potential of the medicinal halophyte Artemisia campestris subsp. maritima (dune wormwood) as a source of health promoting commodities. For that purpose, infusions, decoctions and tinctures were prepared from roots and aerial-organs and evaluated for in vitro antioxidant, anti-diabetic and tyrosinase-inhibitory potential, and also for polyphenolic and mineral contents and toxicity. The dune wormwood extracts had high polyphenolic content and several phenolics were identified by ultra-high performance liquid chromatography-photodiode array-mass-spectrometry (UHPLC-PDA-MS). The main compounds were quinic, chlorogenic and caffeic acids, coumarin sulfates and dicaffeoylquinic acids; several of the identified phytoconstituents are here firstly reported in this A. campestris subspecies. Results obtained with this plant's extracts point to nutritional applications as mineral supplementary source, safe for human consumption, as suggested by the moderate to low toxicity of the extracts towards mammalian cell lines. The dune wormwood extracts had in general high antioxidant activity and also the capacity to inhibit a-glucosidase and tyrosinase. In summary, dune wormwood extracts are a significant source of polyphenolic and mineral constituents, antioxidants and a-glucosidase and tyrosinase inhibitors, and thus, relevant for different commercial segments like the pharmaceutical, cosmetic and/or food industries.