•Monoethanolamine and the medium recycle provided more growth cycles for Spirulina.•Cell growth and CO2 fixation were improved by MEA addition.•The Spirulina carbohydrates concentration doubled with ...monoethanolamine addition.
The chemical absorption of carbon dioxide (CO2) is a technique used for the mitigation of the greenhouse effect. However, this process consumes high amounts of energy to regenerate the absorbent and to separate the CO2. CO2 removal by microalgae can be obtained via the photosynthesis process. The objective of this study was to investigate the cultivation and the macromolecules production by Spirulina sp. LEB 18 with the addition of monoethanolamine (MEA) and CO2. In the cultivation with MEA, were obtained higher results of specific growth rate, biomass productivity, CO2 biofixation, CO2 use efficiency, and lower generation time. Besides this, the carbohydrate concentration obtained at the end of this assay was approximately 96.0% higher than the control assay. Therefore, Spirulina can be produced using medium recycle and the addition of MEA, thereby promoting the reduction of CO2 emissions and showing potential for areas that require higher concentrations of carbohydrates, such as in bioethanol production.
•Increase in MEA concentration, there was also an increase in Spirulina growth rate.•MEA concentrations selected were 0.10, 0.20 and 0.41mmolL−1 (0.13gMEAgbiomass−1).•The MEA addition increased the ...protein concentration in biomass Spirulina.
The objective of this study was to select a concentration of CO2 absorbents to supplement Spirulina sp. LEB 18 cultivation and to evaluate the effect of these compounds on the growth and production of macromolecules. Three initial biomass concentrations (X0), eight concentrations of monoethanolamine (MEA), and three NaOH concentrations were tested. The selected MEA concentrations did not inhibit the growth of Spirulina and doubled the dissolved inorganic carbon concentration in the assay medium in relation to the concentration of NaOH. The protein concentration in the biomass grown with MEA was, on average, 17% higher than that obtained with NaOH. Thus, it was found that MEA did not reduce the productivity of Spirulina sp. LEB 18, and its use can be further explored as a means for converting the carbon dissolved in the medium to biomolecules.
•Spirulina biorefinery contribute to greenhouse gases fixation and effluent treatment.•More than 30% of the world biomass production is from genus Spirulina.•Biorefineries are the best alternative ...for the economic performance of Spirulina.
Microalgae biorefinery systems have been extensively studied from the perspective of resources, energy expenditure, biofuel production potential, and high-added value products. The genus Spirulina (Arthrospira) stands out among the microalgae of commercial importance. It accounts for over 30% of biomass produced globally because of high protein concentration and, carotenoid and phycocyanin content. Spirulina cultivation can be used to reduce greenhouse gases and for effluent treatment. Furthermore, its cellular morphology facilitates biomass recovery, which contributes to the process cost reduction. Spirulina biomass is widely applicable in food, feed, cosmetics, biofertilizers, biofuels, and biomaterials. A feasibility analysis of Spirulina biorefinery would provide specific information for the decision-making for the improvement of the Spirulina production process. In that context, this review aimed to present a parameter assessment to contribute to the economic viability of Spirulina production in a biorefinery system.
•Chlorella fusca LEB 111 was more tolerant to monoethanolamine than Chlorella sp.•Addition of MEA increased the dissolved inorganic carbon by approximately 25%.•Higher MEA concentrations increased ...the CO2 use efficiency by C. fusca LEB 111.•MEA addition increased the carbohydrates and lipids in the C. fusca LEB 111 biomass.
This study aimed to assess the growth of Chlorella strains isolated from adverse environments at various concentrations of monoethanolamine (MEA), evaluating the CO2 fixation and macromolecule production. For this purpose, the green algae Chlorella sp. and Chlorella fusca LEB 111 were tested against five concentrations of MEA: 50, 75, 100, 200 and 300 mg L−1. The strain C. fusca LEB 111 exhibited higher tolerance to MEA as well as higher accumulation of dissolved inorganic carbon and efficiency of CO2 utilization (approximately 37.0% w w−1) with the addition of 100 and 150 mg L−1 of MEA. In addition, the highest carbohydrate productivity and the highest lipid productivity were obtained with 50 and 100 mg L−1 of MEA, respectively. Thus, the absorbent increased the carbon concentration in the medium, and its use in culture can be exploited by C. fusca LEB 111 to produce higher macromolecule concentrations.
ABSTRACT Microalgae are efficient at using solar energy to turn CO2 and nutrients into biomass containing lipids, proteins, carbohydrates and other compounds that may be used to produce bioproducts ...for human and animal consumption and pharmaceutical use. The aim of this study was to assess the effect of the NaNO3 and NaCl concentration on the growth kinetics, the biomass composition and the ability to biofix CO2 using the microalga Spirulina sp. LEB 18. The assays were carried out according to a 22 central composite design (CCD) with different concentrations of NaNO3 (1.25, 1.88 and 2.50 g L-1) and NaCl (1.00, 15.0 and 30.0 g L-1). The assays were carried out in 2 L vertical tubular photobioreactors at 30°C, 12 h light/dark and an injection of 12.0% v/v of CO2 at 0.3 vvm. The best growing results (Xmax = 1.60 g L-1, Pmax = 0.109 g L-1 d-1, μmax = 0.208 d-1) and CO2 biofixation rate (197.4 mg L-1 d-1) were observed in the assay with 1.25 g L-1 NaNO3 and 1.00 g L-1 NaCl. Increasing the NaCl concentration produced biomass with a higher carbohydrate content, while increasing the NaNO3 concentration reduced the protein concentration. According to the results, in addition to using Spirulina as a source of protein, it can also be used as a source of carbohydrates and to biologically remove CO2 from the atmosphere.
•Biomass productivity increased with the use of smaller flow rate and porous diffuser.•Most injection flow rate increased the values of carbohydrate content in the biomass.•The use of lower flows ...rates and porous diffusers promote increased CO2 fixation.
The carbon dioxide (CO2) emissions from fossil fuels contributes to global warming. This phenomenon became a major political issue in the fields of science, environment, and economy in current years. Microalgae can convert CO2 into biomass and oxygen through the photosynthesis. The aim of this study was to evaluate the influence of diffusers configuration and CO2 flow rate in mass transfer, CO2 fixation efficiency by Spirulina and in the biomass composition produced. Two flow rates (0.05 and 0.3vvm) and four diffusers (sintered stone (SS), porous curtain (PC), perforated ring (PR) and porous wood (PW)) were used in this study. The maximum CO2 mass transfer coefficient (123.2h−1) in the CO2–H2O system corresponded to the higher flow rate (0.3vvm) using the diffuser porous curtain (PC). The maximum biomass productivity (125.9±5.3mgL−1d−1) was observed for PC with a flow rate of 0.05vvm. Increasing the flow rate (0.3vvm) with PC resulted in a 26% increase in the carbohydrate content in biomass. The results showed a smaller flow rate with porous diffusers might promote an increase in CO2 fixation efficiency by microalgae.
Microalgal production conducted outdoors using low-cost cultivation media is important for the consolidation of this bioprocess on a large scale. In this context, the use of a chemically defined ...medium with reduced costs can not only provide nutritional security but also contribute to an increase in the concentration of biomolecules without a loss of microalgal biomass productivity. Thus, this study aimed to evaluate the biomass production and biomolecule concentrations of
Spirulina
sp. LEB 18 and
Synechococcus nidulans
LEB 115 in outdoor cultivation using media containing reduced nutrients. Algal performance was assessed in open raceway bioreactors, using three different culture media, namely, BG-11, standard Zarrouk, and a modified Zarrouk reduction in the sources of carbon (83%), phosphorus (94%), nitrogen (40%), and magnesium (63%) concerning the standard Zarrouk medium. Cultivation of
Spirulina
sp. LEB 18 in the modified Zarrouk medium promoted the shortest generation time (2.10 days), with the concentration of carbohydrate produced (37.1%) being 346% higher than that produced using the standard Zarrouk medium (8.3%). Similarly, compared with the Zarrouk medium, the modified Zarrouk medium promoted higher biomass productivity of
S
.
nidulans
LEB 115 (0.19 g L
−1
d
−1
) along with a 160% increase in the concentration of carbohydrates (21.6%) produced by this strain. Thus, for the examined microalgal strains, the use of the modified Zarrouk medium enhanced the potential carbohydrate production and maintained the protein concentration above 39%, thereby indicating that this medium would be a promising candidate for the cost-effective large-scale production of microalgal biomass.
The objective of this study was to evaluate biomass production, CO
2
fixation, and biomolecule production in a semicontinuous
Chlorella fusca
LEB 111 culture process with the addition of ...monoethanolamine and nutrient reuse. The assays were performed varying the blend concentration (0.6, 0.8, and 1.0 g L
−1
) and medium reuse rate (30, 50, and 70% v v
−1
) according to a 2
2
central composite design. Blend concentration was the biomass concentration value used as a control to remove the cultivated medium for the reuse of nutrients. The highest carbohydrate concentration (35.7% w w
−1
), biomass productivity (144.2 mg L
−1
day
−1
), generated biomass (1.8 g), and CO
2
use efficiency (41.5% w w
−1
) were achieved with the use of a medium reuse rate of 70% v v
−1
, blend concentration of 1.0 g L
−1
, and three monoethanolamine additions (50 mg L
−1
per growth cycle). Moreover, the synergy of biological and chemical processes produced biomass with a high lipid concentration (~ 41.0% w w
−1
) at a medium reuse rate of 50% v v
−1
, blend concentration of 0.8 g L
−1
, and also three monoethanolamine additions.
Graphical abstract
The heavy metal mercury (Hg) is one of the most complex and toxic pollutants. When present in soils, it may impair plant growth, but the intensity of damage depends on the physical-chemical ...properties of the soil such as pH, clay, and organic matter content, which in turn affects Hg sorption and bioavailability. Understanding Hg potential damage to staple food crops is of paramount relevance. Here, we evaluated the physiological effects of Hg in
Phaseolus vulgaris
(common bean) and
Avena sativa
(oat) cultivated in two Oxisols with contrasting properties: Rhodic Acrudox (RA) and Typic Hapludox (TH). We performed four independent experiments (one per species/soil combination) that lasted 30 days each. Treatments were composed by HgCl
2
concentrations in soils (0 to 80 mg kg
−1
Hg). At the end of the experiment, we determined the impact of Hg on photosynthesis, nutritional status, and oxidative stress. Cultivation in TH contaminated with Hg resulted in oxidative stress in common bean and decreased photosynthesis/P accumulation in oat. No deleterious effects on physiological variables were detected in both species when cultivated in the RA soil. In general, we conclude that the lower Hg sorption in the TH soil resulted in toxicity-like responses, while acclimation-like responses were observed in plants cultivated in RA, reinforcing soil physical-chemical properties as key features driving Hg toxicity in Oxisols.
Graphical abstract
The microalgae cultivation can be used as alternative sources of food, in agriculture, residual water treatment, and biofuels production. Semicontinuous cultivation is little studied but is more ...cost-effective than the discontinuous (batch) cultivation. In the semicontinuous cultivation, the microalga is maintained in better concentration of nutrients and the photoinhibition by excessive cell is reduced. Thus, biomass productivity and biocompounds of interest, such as lipid productivity, may be higher than in batch cultivation. The objective of this study was to examine the influence of blend concentration, medium renewal rate, and concentration of sodium bicarbonate on the growth of Chlorella sp. during semicontinuous cultivation. The cultivation was carried out in Raceway type bioreactors of 6 L, for 40 d at 30°C, 41.6 µmol m−2 s−1, and a 12 h light/dark photoperiod. Maximum specific growth rate (0.149 d−1) and generating biomass (2.89 g L−1) were obtained when the blend concentration was 0.80 g L−1, the medium renewal rate was 40%, and NaHCO3 was 1.60 g L−1. The average productivity (0.091 g L−1 d−1) was achieved with 0.8 g L−1 of blend concentration and NaHCO3 concentration of 1.6 g L−1, independent of the medium renewal rate.
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