Mixotrophic growth of the microalga Phaeodactylum tricornutum Influence of different nitrogen and organic carbon sources on productivity and biomass composition (original) (raw)
Related papers
Mixotrophic growth of the microalga Phaeodactylum tricornutum
Process Biochemistry, 2005
The mixotrophic growth of the diatom Phaeodactylum tricornutum UTEX-640 was studied using diverse substrates at different concentrations in discontinuous and fed-batch modes. The nutrients used were acetate (0.005-0.1 M), starch (0.5-5 g l −1), lactic acid (0.005-0.1 M), glycine (0.005-0.02 M), glucose (0.5-5 g l −1) and glycerol (0.005-0.1 M). Biomass concentration and biochemical profile were monitored. The capacity of the different nutrients to promote mixotrophic growth varied not only with its nature, but also with the concentration used for the experiment, showing how comparisons at the same concentration may be misleading. Subsequent fed-batch cultures using glycerol (0.1 M), and supplemented urea (0.01 M) and sodium nitrate (1 g l −1) as nitrogen sources, showed that repeated additions of organic substrate can sustain mixotrophic growth at very high density cultures. The best results were obtained using with urea (0.01 M), which resulted in maximum biomass and eicosapentaenoic acid productivities that were, respectively, 1.52 g l −1 per day and 43.13 mg l −1 per day, significantly higher than those obtained for the photoautotrophic control. Although the results reported here were obtained in flask cultures of only 1 l working volume and under low irradiance (165 Em −2 s −1), similar data were reported for photoautotrophic growth on glycerol of this same strain in outdoor pilot-scale tubular photobioreactors (tube diameter 3 and 6 cm and to 50 and 200 l working volume, respectively), which suggest the possibility of using mixotrophy for the mass production of microalgae.
Algal Research, 2015
The practicability of culturing microalgae in mixotrophic mode is evaluated for pilot-scale photobioreactor systems, as a general consideration for new process development: higher biomass production rates, production of (potentially new) high-value products from algae and the transformation (recovery) of other carbon sources are the typical advantages of this production mode. This study is conducted with Scenedesmus obliquus, a species known for its ability to assimilate a wide variety of carbon sources. Autotrophic experiments are first conducted to obtain the typical behavior (growth curve and nutrient consumption rates) of the alga in standard medium composition. Mixotrophic experiments then follow: aside from productivity aspects, results show that bacterial contaminations can remain an issue at this scale, even for closed systems such as photobioreactors. It is however shown possible to exploit some intrinsic dynamic properties of the algae to limit bacterial growth, with no significant impact on algal growth and biomass productivity. Anionic analyses on the mixotrophic cultures show that particular attention should be drawn on the phosphate and sulfate ions for further process optimization.
Effect of light conditions on mixotrophic cultivation of green microalgae
Bioresource Technology, 2019
Current research aimed to increase mixotrophic biomass from various organic carbon sources by exploring best light conditions. Three substrates glucose, acetic acid and glycerol were studied for their effects on mixotrophic microalgae cultivation under four light conditions. Light irradiance exhibited variability in growth response and photosynthetic efficiency based on type of substrates used in mixotrophic growth. Each substrate showed variability in light requirements for their effective assimilations. From growth responses, glucose and acetic acid respectively exhibited heterotrophic and mixotrophic (better growth in light) natures. Continuous light-deficient condition was adequate for effective mixotrophic growth as well as energy saving for glucose. However, light-sufficient condition required for effective acetic acid supported mixotrophic growth. Mixotrophic benefits from glycerol and its uptake by Chlorella protothecoides was negligible in all light conditions. Investigation of heterotrophic biomass contribution by various substrates in overall mixotrophic yield, glucose offered maximum approx. 43% contribution.
Phaeodactylum Tricornutum Microalgae Growth Rate in Heterotrophic and Mixotrophic Conditions
Revista de Engenharia Térmica, 2009
The Brazilian National Program for Biofuel Production has been encouraging diversification of feedstock for biofuel production. One of the most promising alternatives is the use of microalgae biomass for biofuel production. The cultivation of microalgae is conducted in aquatic systems, therefore microalgae oil production does not compete with agricultural land. Microalgae have greater photosynthetic efficiency than higher plants and are efficient fixing CO2. The challenge is to reduce production costs, which can be minimized by increasing productivity and oil biomass. Aiming to increase the production of microalgae biomass, mixotrophic cultivation, with the addition of glycerol has been shown to be very promising. During the production of biodiesel from microalgae there is availability of glycerol as a side product of the transesterification reaction, which could be used as organic carbon source for microalgae mixotrophic growth, resulting in increased biomass productivity. In this ...
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...
Biotechnology Progress, 2004
Pilot-scale (0.19 m column diameter, 2 m tall, and 60 L working volume) outdoor vertical bubble column (BC) and airlift photobioreactors (a split-cylinder (SC) and a draft-tube airlift device (DT)) were compared for fed-batch mixotrophic culture of the microalga Phaeodactylum tricornutum UTEX 640. The cultures were started photoautotrophically until the onset of a quasi-steady-state biomass concentration of 3.4 g L-1. After this, the cultures were supplemented with organic nutrient (glycerol 0.1 M) and a reduced nitrogen source, resulting in an immediate growth rate boost, which was repeated with successive additions of nutrients in all three photobioreactors. During this period the biomass productivity was enhanced compared to photoautotrophic cultures in the three reactors, although differences were found among them. These could be attributed to the different hydrodynamic behavior influencing the transport phenomena inside the cultures. A 25.4 g L-1 maximum biomass concentration was attained in the SC. Further additions of nutrients did not promote any more growth. The consumption of glycerol was quantitative in the first additions but slowed at high biomass concentration, suggesting that a minimum amount of light is needed to sustain growth. No significant effect of the supplied organic nutrient on carotenoids and chlorophylls content was observed, although it had a profound effect on the fatty acid composition. Eicosapentaenoic acid (EPA) content was increased up to 3% (DW) in mixotrophic growth, giving a productivity of 56 mg L-1 d-1 , a significant increase compared to the photoautotrophic control, which yielded a maximum EPA content of 1.9% (DW) and a productivity of 18 mg L-1 d-1. The maximum biomass and EPA volumetric yields obtained in this work are comparable with those reported for commercial photoautotrophic monoculture of large quantities of P. tricornutum in closed continuous-run tubular loop bioreactors with tubes that are typically less than 0.08 m in diameter. When the comparison is established in terms of productivities based on the land area occupied, the vertical airlift and bubble-column bioreactors are extraordinarily more productive.
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.
Photo-mixotrophic Cultivation of Algae
In the future, due to limited resources, a crisis of energy storing molecules (fuels), which are currently produced from crude mineral oil, is expected. One strategy to compensate a part of the oil defi ciency is the production of biodiesel from microalgal lipids. As model microorganism for lipid production microalgae Euglena gracilis was selected and photo-mixotrophic cultivation was performed in the stirred tank photobioreactor. During this research, medium composition and operational conditions of photo-bioreactor were optimized in order to defi ne adequate cultivation conditions for algae biomass and lipid production. As low-cost and available complex carbon/ nitrogen source, corn steep liquor (CSL) was used to promote E. gracilis growth and lipid production. Due to the optimization of medium composition and cultivation conditions, lipid production was increased up to 29% of biomass dry weight in a two stage cultivation process inside one photo-bioreactor. Promising results obtained in this research encouraged us for further investigation.
Enzyme and Microbial Technology, 2002
Relatively large (0.19 m column diameter, 2 m tall, 0.06 m 3 working volume) outdoor bubble column and airlift bioreactors (a split-cylinder and a draft-tube airlift device) were compared for monoseptic fed-batch culture of the microalga Phaeodactylum tricornutum. The three photobioreactors produced similar biomass versus time profiles and final biomass concentration (∼4 kg m −3). The maximum specific growth rate observed within a daily illuminated period in the exponential growth phase, had a value of 0.08 h −1 on the third day of culture. Because of night-time losses of biomass, the specific growth rate averaged over the 4-days of exponential phase was 0.021 h −1 for the three reactors. The biomass in the vertical column reactors did not experience photoinhibition under conditions (photosynthetically active daily averaged irradiance value of 1150 ± 52 E m −2 s −1) that are known to cause photoinhibition in conventional thin-tube horizontal loop reactors. Because of good gas-liquid mass transfer, the dissolved oxygen concentration in the reactors at peak photosynthesis remained <120% of air saturation; thus, oxygen inhibition of photosynthesis and photo-oxidation of the biomass did not occur. Carbohydrate accumulation (up to ∼13% w/w) by the biomass was favored during light-limited linear growth. A declining light intensity caused a more than five-fold increase in cellular carotenoids but the chlorophylls increased only by about 2.5-fold during the course of the culture. In the stationary phase, up to 2% of the biomass was chlorophylls and carotenoids constituted up to 0.5% of the biomass dry weight.
Cultivation of Microalgae Euglena Gracilis: Mixotrophic Growth in Photobioreactor
MOJ Food Processing & Technology, 2017
Microalgae Euglena gracilis was used for lipid production. Photo-mixotrophic cultivation was done in self-constructed photobioreactor. During cultivation carbon source, stirrer speed, aeration rate and light source were changed to provide suitable cultivation condition for algae biomass and lipid production. It was find out that the changing from heterotrophic to autotrophic condition increase lipid production. Stirrer speed and aeration rate has a more pronounced effect on the biomass production. Due to the optimization of cultivation conditions, lipid production was increased from 0.4% to 30% of biomass dry weight in a single bioreactor. During autotrophic cultivation CO 2 increase lipid production in the E. gracilis cells but it has negative impact on the biomass production.