Improvement of medium composition for heterotrophic cultivation of green microalgae,< i> Tetraselmis suecica, using response surface methodology (original) (raw)
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Biochemical …, 2010
Optimization of medium composition for the improvement of heterotrophic cultivation of green microalgae, Tetraselmis suecica, was performed using response surface methodology (RSM). Heterotrophic cultivation of T. suecica was conducted in total darkness using Walne medium formulated with natural sea water. Initially, the effect of two types of carbon source (glucose and sodium acetate) and various types of nitrogen source (peptone, yeast extract, meat extract, malt extract, urea, sodium nitrate and ammonium nitrate) on growth of T. suecica was studied. The concentration of medium component that was found to significantly influence the heterotrophic growth of T. suecica (glucose, peptone, yeast extract and meat extract) was further optimized using RSM. The medium that consists of 5.78 g/L glucose, 9 g/L peptone, 4.48 g/L yeast extract and 3.01 g/L meat extract was found optimal for heterotrophic cultivation of T. suecica. The final cell concentration (28.88 g/L) obtained in heterotrophic cultivation using this optimized medium was about 3 and 2 times higher than obtained in photoautotrophic culture (8.40 g/L) and non-optimized medium for heterotrophic cultivation (13.81 g/L), respectively. In addition, the cell yield based on glucose consumed (9.31 g cell/g glucose) was increased by about 3 times as compared to non-optimized medium (3.61 g cell/g glucose).
2020
This study aimed to evaluate the influence of photoand hetero-trophic culture conditions on growth performance and microanatomy changes of microalga, Tetraselmis suecica shake flask and stirred tank bioreactor. The changes in cell composition such as lipid, protein and carbohydrate content were determined and the kinetic parameters and microanatomy of T. suecica under heterotroand photo-autotrophic conditions were studied. Results revealed that lipid content in the heterotrophic cells was about two times higher when compared to that of photoautotrophic cells. The final cell concentration obtained at the end of exponential phase in heterotrophic cultivation (74 g.L-1) was higher than that obtained in photoautotrophic cultivation (13.7 g.L-1), in photobioreactor. The shape of photoautotrophic T. suecica cells was oval (12.5 μm long and 7.5 μm wide) with a volume of about 552 μm3. In heterotrophic cultivation, the cell was changed to a spherical shape with a diameter of approximately 3...
The Open Biotechnology Journal, 2010
The effectiveness of various physical and chemical methods for the removal of contaminants from the microalgae, Tetraselmis suecica, culture was investigated. The information obtained was used as the basis for the development of improved protocol for the preparation of axenic culture to be adapted to heterotrophic cultivation. Repeated centrifugation and rinsing effectively removed the free bacterial contaminants from the microalgae culture while sonication helped to loosen up the tightly attached bacterial contaminants on the microalgae cells. Removal of bacterial spores was accomplished using a mixture of two antibiotics, 5 mg/mL vancomycine and 10 mg/mL neomycine. Walne medium formulation with natural seawater was preferred for the enhancement of growth of T. suecica. Adaptation of growth from photoautotrophic to heterotrophic conditions was achieved by the repeated cultivation of photoautotrophic culture with sequential reduction in illumination time, and finally the culture was inoculated into the medium containing 10 g/L glucose, incubated in total darkness to obtain heterotrophic cells. Changes in the morphology and composition of T. suecica cells during the adaptation from photoautotrophic to heterotrophic condition, as examined under Transmission Electron Microscope, were also reported.
Influence of Different Culture Conditions on Yield of Biomass and Value Added Products in Microalgae
Microalgae viz., Botryococcus, Haematococcus and Dunaliella, were studied for their adaptability to different culture conditions. Botryococcus strains of indigenous origin and culture collection centres were studied for their growth, hydrocarbon and lipid profile and for their biomass yields under different bicarbonate concentrations. Growth of Haematococcus was compared in autotrophic (ambient and enriched CO 2 atmosphere) and heterotrophic culture conditions. Influence of ammonium salts, urea and commercial fertilizers as nitrogen source under autotrophic conditions and different amino acids as nitrogen source under heterotrophic culture conditions, was studied on growth and astaxanthin content of Haematococcus. Influence of different salinities was studied on growth and-Carotene content of Dunaliella in AS100 and De Walnes media. Results indicated that Botryococcus strains varied in their biomass yields (0.25-2 g L-1), hydrocarbon content (15-60% w/w) and lipid content (15-30%, w/w). An indigenous strain was able to grow at all the tested concentrations of bicarbonate with maximum biomass yield at 0.25 g L-1. The growth rate of Haematococcus was higher in heterotrophic medium with a cell count of 41-44 × 10 4 on 5 th day after inoculation. The supplementation of autotrophic medium with 2% CO 2 led to a 4-fold increase in cell count. Use of DAP as nitrogen source showed a 20% increase in yield of encysted biomass. Both DAP and Suphala led to astaxanthin productivity of 46-48 g L-1. Haematococcus was able to utilize all the amino acids at tested concentrations in heterotrophic culture conditions. Enhanced growth of Dunaliella was observed at 1.0 M NaCl concentration in both the AS 100 and De Walnes media while 2.0M NaCl in De Walnes medium showed higher-carotene content (45.6 mg g-1).
Optimization of culture conditions and comparison of biomass productivity of three green algae
Bioprocess and Biosystems Engineering, 2011
Culture conditions for the mass production of three green algae, Chlorella sp., Dunaliella salina DCCBC2 and Dunaliella sp., were optimized using a response surface methodology (RSM). A central composite design was applied to investigate the effects of initial pH, nitrogen and phosphate concentrations on the cultivation of microalgae. The optimal growth conditions estimated from the design are as follows: Chlorella sp. (initial pH 7.2, ammonium 17 mM, phosphate 1.2 mM), D. salina DCCBC2 (initial pH 8.0, nitrate 3.3 mM, phosphate 0.0375 mM) and Dunaliella sp. (initial pH 8.0, nitrate 3.7 mM, phosphate 0.17 mM). Culturing the microalgae with the optimized conditions confirmed that the maximum growth rates were attained for these parameters. The optimum CO 2 concentrations of Chlorella sp., D. salina DCCBC2 and Dunaliella sp. were 1.0, 3.0 and 1.0% (v/v), respectively. The specific growth rates (l) of Chlorella sp., D. salina DCCBC2 and Dunaliella sp. were 0.58, 0.78 and 0.56 day-1 , respectively, and the biomass productivities were 0.28, 0.54 and 0.30 g dry cell wt l-1 day-1 , respectively. The CO 2 fixation rates of Chlorella sp., D. salina DCCBC2 and Dunaliella sp. were 42.8, 90.9 and 45.5 mg l-1 day-1 , respectively. Mixotrophic cultivation of Chlorella sp. with glucose increased biomass productivity from 0.28 to 0.51 g dry cell wt l-1 day-1. However, D. salina DCCBC2 and Dunaliella sp. were not stimulated by several organic compounds tested.
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.
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.