Improvement of medium composition for heterotrophic cultivation of green microalgae,< i> Tetraselmis suecica, using response surface methodology (original) (raw)
Chemical Engineering Transactions
Microalgae are well known for their ability to grow photoautotrophically, however higher biomass yields have been reported when microalgae was grown heterotrophically. The feasibility of large scale cultures of microalgae in heterotrophic conditions is still limited by, among other things, the high cost of nutrients and organic substrates used in this type of cultivation. This work aims to explore the utilization of different low cost carbon sources for the cultivation of two different strains of microalgae. Cassava wastewater, sugarcane molasses, glycerol, xylose, sucrose and sodium acetate were tested as carbon sources for Chlorella vulgaris and Scenedesmus bijugus cultures. Glucose and fructose were also tested as reference carbon sources. The methodology of miniaturized growth allowed the screening of different substrates and conditions of the medium much faster than other methodologies (shaking flasks, bioreactor). The results demonstrate the feasibility of the miniaturized culture methodology in the development and evaluation of heterotrophic cultivation of microalgae. The main observed problems were settling of cells, evaporation of the medium during the experiment and interference in spectrophotometric reading (caused by water condensation on the lid), which had to be solved to adapt the methodology of miniature culture to heterotrophic microalgae cultivation. The evaluated microalgae strains presented different growth behaviours in the different carbon sources tested. Cassava wastewater and sugarcane molasses hydrolyzed allowed higher biomass production and proved to be a suitable low cost substrate for increasing algae-based processes feasibility.
Aquacultural Engineering, 1987
We report the possibility of an economic cultivation of the marine microalga Tetraselmis suecica, using different mixtures of a common garden fertilizer, soil extract, micronutrients and vitamins. Maximum cellular densities were obtained with a nitrogen concentration of 14 μg/ml and maximum protein concentrations were obtained with 28 μg N/ml, in all cases. The mixture of fertilizer + soil extract + micronutrients gave the best results for obtaining maximum cellular densities and protein concentrations per ml of culture. An economic evaluation showed a maximum of 2770 g of microalgal protein/dollar and 210 × 10 12 microalgal cells/dollar with the mixture of the fertilizer and soil extract.
A possible source of biological material for the production of biodiesel is represented by microalgae, in particular by their lipid content. The aim of the present work was to optimize culture medium composition for improving growth and lipid content of green microalgae Chlorella sorokiniana, Scenedesmus acuminatus and blue green Cyanobacterium aponicum. Lipids were quantitatively determined by spectrofluorometric method using Nile red flurometric stain. Initially, the effect of two different medium types, Bold's and optimized culture medium (OCM), four types of carbon source (glucose and sodium acetate, molasses, glycerol, control) and four nitrogen concentrations (100%, −75%, −50%, −25%) on the enhancement of biomass and lipid content and lipid productivity were studied; indeed, optimized culture medium significantly improved growth, CDW for three microalgae, beside increasing lipid content and lipid productivity for S. acuminatus and C. aponicum by 7.5 and 5 folds respectively at 25 th day compared to Bold's medium. Moreover, 25% nitrogen deficient medium significantly increased lipid content and lipid productivity for both C. sorokiniana and C. aponicum at 2 nd week of re-propagation to 10.6 and 2.6 folds over control (100% nitrogen). While S. acuminatus recorded the significant lipid content & productivity at 2 nd week under recommended nitrogen dose in medium (100% N) by 4.4 folds over 25% deficient medium. Meanwhile 0.3% glycerol medium enhanced CDW, lipid content of S. acuminatus to 1.68 gL −1 . While C. sorokiniana and C. aponicum recorded significant CDW under 0.3% acetate medium 1.37 and 0.76 gL −1 . C. aponicum exhibited no growth under glycerol medium. The highest lipid content and lipid productivity were obtained under glycerol medium for C. sorokiniana and S. acuminatus (64.3 and 52.8 mg·g −1 and 5.4, 4.4 mg·g −1 ·d −1 ).
Materials and Methods 2 . 1 Algal source and cultivation methodology
2015
Alternative renewable energy is considered the optimal solution to solve the global energy crisis. Biofuel is one of the promising alternatives; especially that are produced from microalgae. Microalgae have the potential to produce 5000 – 15000 gallons biodiesel/ (acre-year). However, there are challenges; these include high yield of biomass and high lipid content. In this paper the authors studied the concentration of inoculum and the light penetration as a part of the parameters affecting the kinetics of the cultivation process of local strains of microalgae (Spirulina platensis, Scenedesmus obliquus, and Nannochloropsis sp.) that isolated from the Nile to obtain the maximum amount of oil, applying the factors affecting algal growth as light intensity, mixing, temperature and aeration for optimal design of photo-bioreactor. The achieved productivity was 0.54 g/l of algae biomass in 13 days with doubling time 2.8 days and specific growth rate 0.25 d. Optimizing the culture dense an...
Nutritional value changes in response to temperature, microalgae mono and mixed cultures
Acta Limnologica Brasiliensia
Aim The response of mixed cultures and monocultures of Pseudopediastrum boryanum (Turpin) E. Hegewald and Scenedesmus obliquus (Turpin) Kützing was assessed in the laboratory at three different temperatures: 20, 30 and 40 °C. The change in biomass and biochemical composition of these cultures was evaluated. Methods Microalgae were placed in a batch culture over 21-days in ASM1 medium. Cell density was directly counted every two days using a Fuchs-Rosenthal hemocytometer. Chlorophyll ‘a’ and total carotenoids were extracted twice. Protein, carbohydrate, total lipid and fatty acid contents were determined at the end of the experiment. Results Cultures grown in 40 °C exhibited no growth. However, there was increased cell density (13.6 x 106 cell.mL-1) and biomass (55 g.L-1) in the S. obliquus monoculture at 30 °C. High protein concentrations (672.6 mg.g-1) were observed in monocultures P. boryanum and S. obliquus at 20 °C treatments. There were high carbohydrate concentrations (6.17 mg...
Development of an optimal heterotrophic growth medium for Chlorella vulgaris
~inal biomass yields of Chlorella vulgaris cultured heterotrophically in bristol medium amended with 0.1% (w/v) yeast extract (Difco) or 0.5% glucose (w/v) were 26 and 5b times higher, respectively, than yields obtained for autotrophically grown cells in the light. Similarly, final biomass increases were 35 and 138 fold for these organic substrates in the dark. The mixture of 0.1% yeast extract and 0.5% glucose was optimal and produced increases in final biomass of 70 and 140 times in the light and dark, respectively.
International Journal of Applied and Natural Sciences (IJANS), 2018
Microalgae require a wide range of chemical and physical factors for their growth, proliferation, and differentiation. These factors affect the morphology, physiology and metabolic activities of the organism. Therefore, in the present investigation, lipid producing microalgae were isolated and identified, abiotic growth factors such as different autotropic media, pH, nutrients, and media optimization studies were carried out to obtain highest biomass and lipid from microalgae which have the potential for effective biodiesel production. Growth studies were carried out of the isolated algal strains, the optimum temperature for all the experiments was kept at 25 ± 1 o C and light intensity of 1.2 ± 0.2 klux was maintained. Four strains with highest percentage wise Biomass : Lipid ratio were considered for studies, these strains are Chlorella vulgaris AS-3, Chlorella pyrenoidosa AS-6, Scenedesmus dimorphus AS-13, all 3 strains were isolated from unkal lake and Scenedesmus quadricauda AS-18 was isolated from Rayanaal lake. Out of the four isolated strains Chlorella vulgaris (AS-3) showed a significant increase in lipid content by 3 %. The organism was found to grow well in the optimized BG-11 media with the pH of 6.5 and culture age of 6 weeks and concentration of sodium nitrate, FAC, potassium bicarbonate and magnesium sulphate of 2, 0.24, 0.3 and 0.8 g/L respectively. The data obtained by the by the above growth studies can be used for mass culturing of the organism in invivo conditions in open ponds and furthers studies can be done using different media compositions. Hence, AS-3 was found to be an ideal candidate for biodiesel production and further characterization of the microalgae was carried out.
2014
The alga Trachydiscus minutus, while being a relatively new subject of laboratory research, is not yet involved in a real biotechnological development. The aim of this study was an elaboration of the intensive growth conditions. A new medium specifically designed for the cultivation of the alga was composed, and the reasons were discussed. The use of the new medium leads to at least 10% higher growth than media previously used. The maximal growth rate of the alga remains the same, but the growth is comparatively higher before achieving plateau-phase, which is due to a better composition. The new medium is significantly cheaper per 1 kg algal biomass. Attention was paid to precise light and temperature conditions. The separation of Trachydiscus biomass is discussed as an important part of its biotechnology. The biochemical composition of the alga at these conditions is described. The paper is targeted to micro-enterprises in accordance with their limited resources.
Heterotrophic growth of microalgae: metabolic aspects
World Journal of Microbiology and Biotechnology, 2014
Microalgae are considered photoautotrophic organisms, however several species have been found living in environments where autotrophic metabolism is not viable. Heterotrophic cultivation, i.e. cell growth and propagation with the use of an external carbon source under dark conditions, can be used to study the metabolic aspects of microalgae that are not strictly related to photoautotrophic growth and to obtain high value products. This manuscript reviews studies related to the metabolic aspects of heterotrophic grow of microalga. From the physiological and metabolic perspective, the screening of microalgal strains in different environments and the development of molecular and metabolic engineering tools, will lead to an increase in the number of known microalgae species that growth under strict heterotrophic conditions and the variety of carbon sources used by these microorganisms.
Heterotrophic cultures of microalgae: metabolism and potential products
Water research, 2011
This review analyzes the current state of a specific niche of microalgae cultivation; heterotrophic growth in the dark supported by a carbon source replacing the traditional support of light energy. This unique ability of essentially photosynthetic microorganisms is shared by several species of microalgae. Where possible, heterotrophic growth overcomes major limitations of producing useful products from microalgae: dependency on light which significantly complicates the process, increase costs, and reduced production of potentially useful products. As a general role, and in most cases, heterotrophic cultivation is far cheaper, simpler to construct facilities, and easier than autotrophic cultivation to maintain on a large scale. This capacity allows expansion of useful applications from diverse species that is now very limited as a result of elevated costs of autotrophy; consequently, exploitation of microalgae is restricted to small volume of high-value products. Heterotrophic culti...