RESUMO
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 300â¯mgâ¯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%â¯wâ¯w-1) with the addition of 100 and 150â¯mgâ¯L-1 of MEA. In addition, the highest carbohydrate productivity and the highest lipid productivity were obtained with 50 and 100â¯mgâ¯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.
Assuntos
Dióxido de Carbono/química , Chlorella , Etanolamina/metabolismo , Biomassa , Carbono , Substâncias MacromolecularesRESUMO
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.
RESUMO
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.