Search

Haematococcus pluvialis is a freshwater microalgae that primarily produces astaxanthin. This carotenoid is used as a pigment and as a bioactive compound in different industries such as food, nutraceutical, pharmaceutical, cosmetics, aquaculture and textiles. In this study, the variables related to light - such as the sources used, the use of photobioreactors, the appropriate photoperiod, the exact value of irradiance and color - were determined and then related to the expression of genes for obtaining astaxanthin in greater quantities. This carotenoid presented its highest production between 81.19 mg/L and 167.97 mg/L, when white fluorescent lamps with irradiances between 150 and 400 μmol m-2 s-1 were used. With the use of red and blue LEDs with white LED, using irradiances between 135 and 400 μmol m-2 s-1, astaxanthin concentrations of 82.82 ± 3.29 mg/L and 151.8mg/L were obtained, respectively. The use of blue and white LEDs increased the expression of the psy and CrtO/bkt genes, significant for accumulating astaxanthin. This research contributes to the technological feasibility of using LEDs due to the advantages they present, the diversity of their sizes (from small), their lightness, durability and efficiency in terms of longer useful life. Furthermore, the amount of light they give off is much greater compared to their energy consumption. Our contribution to technological and biotechnological advances related to the production of astaxanthin can be adapted to the use of photobioreactors, to optimize the cultivation conditions and production of astaxanthin in H. pluvialis. [ABSTRACT FROM AUTHOR]

Copyright of Gestión y Ambiente is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The biofixation capacity of carbon dioxide by the Chlorella vulgaris and Scenedesmus obliquus species cultivated in photobioreactors was evaluated in a 12:12 h photoperiod. A completely randomized experimental design was used, whose sources of variation were: microalgal species and CO2 dosage (0.36, 11.44 and 22.62 g.d-1). The photobioreactors were plastic units with 3.8 L of culture medium (NPK solution + micronutrients), and artificial lighting with a 4400 lumens fluorescent lamp. The following variables were estimated: biomass productivity using the dry weight methodology, CO2 biofixation by numerical method and CO2 removal efficiency in percentage. The results were subjected to the analysis of variance and Tukey's mean tests (p <0.05). Higher biomass productivity and CO2 biofixation were recorded in C. vulgaris compared to S. obliquus. The highest biofixation of CO2 by C. vulgaris and S. obliquus was recorded at the dose of 11.44 gd-1 with 161.79 ± 4.72 and 55.31 ± 0.73 mg.L-1d-1, respectively. The CO2 removal efficiency was significantly higher with the 0.36 g.d-1 dose, registering values of 49.80 ± 3.16 and 39.13 ± 0.57 % for C. vulgaris and S. obliquus respectively. These results suggest the possibility of scaling up low-cost photobioreactors for biofixation of CO2 emissions in industrial fixed fonts, thus contributing to the mitigation of greenhouse gases. [ABSTRACT FROM AUTHOR]

Copyright of Ambiente y Desarrollo is the property of Pontificia Universidad Javeriana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Astaxanthin is an antioxidant carotenoid used in cosmetic, pharmaceutic and food industries that is produced by microalgae H. pluvialis in natural form. It is a secondary metabolite that increases production when microalgae grows under stress conditions, like food deficiency and high irradiation, among others. The goal of this research was to test microalgae growing under nitrogen deficiency conditions in a concentration of 4.0-5.0% and evaluate astaxanthin production and gene expression in dye biosynthesis. For this purpose, a culture in rm medium was carried out with 4.0 and 5.0% nitrogen, using the following conditions: pH 6.7; light/dark cycle 20h: 4h; temperature 25 °C; continuous agitation; 5% CO2; lighting with white fluorescent lamps (Tlt 20w/54rs Philips brand); and a high irradiance of 140 µE. The growth in the medium was used as a control with nitrogen in normal concentrations during 36 days (under the same conditions). Sampling was carried out every third day for quantification of astaxanthin and chlorophyll and the determination of gene expression. The anova performed established that there are no significant differences between treatments (P = 0.053). However, astaxanthin production with a nitrogen concentration of 4.0% and a high irradiance of 140 µE was 3.52x10-6 µg cell-1 x mL-1, increased by 40% when compared to that obtained with 5.0% nitrogen (2.08x10-6 ug cell-1 x mL-1). The psy, pds, lcy, bkt and chy genes were expressed with 4.0% nitrogen, while 5.0% nitrogen only allowed psy, pds and chy. [ABSTRACT FROM AUTHOR]