Microalga Scenedesmus Dimorphus Research Articles

Microalgae production in olive mill wastewater fractions and cattle digestate slurry: Bioremediation effects and suitability for energy and feed uses

The possibility of obtaining energy or nutritive streams and bioremediation as an add-on opens new perspectives for the massive culturing of microalgal biomass on waste waters generated by the agro-food sector. Ordinary revenue streams are fully preserved, or even boosted, if they are used in microalgal cultivation; however, the suitability of wastewaters depends on multiple nutritional and toxic factors. Here, the effect of modulating the Olive Mill Wastewater (OMW) and cattle digestate (CD) fraction in the formulation of a growth medium on biomass accumulation and productivity of selected biomass fractions and their relevance for biofuel and/or feed production were tested for the microalga Scenedesmus dimorphus and for the cyanobacterium Arthrospira platensis (Spirulina). Tests highlighted the strong S. dimorphus adaptability to digestate, as on OMW, compared to A. platensis, with the maximum lipid storage (48 %) when culture medium was composed by 50 % of cattle digestate.

Evaluation of Lipid Profile and Liver Function After Administration of Scenedesmus dimorphus in Obese Mice

Obesity is a major public health problem in developing countries and is a significant risk factor for metabolic disorders. Microalgae Scenedesmus dimorphus (S. dimorphus) contains bioactive compounds such as pigment function as antioxidants, and omega-3 and omega-6 PUFAs have potential as nutraceuticals. The study aimed to evaluate the lipid profile and liver function after the administration of S. dimorphus in obese mice. The research design uses mice which are divided into 6 groups; Group 1 (G1) normal control, G2 control Obesity, G3 treatment with Orlistat, G4 treatment S. dimorphus (0.25mg/g BW), G5 treatment S. dimorphus (0.5 mg/g BW) and G6 treatment S. dimorphus (0.75 mg/g BW) each group consisted of 5 mice and 21 days of observation time. The parameters observed were lipid profile and liver function of mice. Based on the results of the study, the effective dose for treating obesity is a dose of S. dimorphus 0.75 mg/g (BW) can reduce cholesterol, triglycerides, and LDL levels, respectively 67.7 mg/dl, 49.2 mg/dl, 10 , 2 mg/dl, and increased HDL, 68.32 mg/dl compared to control of obesity (G2), respectively 108.7 mg/dl, 139.1 mg/dl, 20.6 mg/dl and HDL 60, 28 mg/dl, this dose is also effective for improving the function of blood pressure by reducing AST and ALT 15.6 U/L and 18.8 U/L, respectively, compared to the obesity group (G2), which is 26.6 U/L, and 29,7 U/L. Based on the results of the study it can be concluded that S. dimorphus is useful for anti-obesity for mice (Mus musculus).

Experimental comparison of biodiesel production performance of two different microalgae

In this study, the fresh water green microalga Scenedesmus dimorphus and the marine golden Isochrysis aff. galbana were compared at the laboratory scale for their potential in biodiesel production. For this purpose, the microalgal strains were grown over five days under the Bristol and Erdschreiber's media conditions. The cultures were supplied with 1.5% carbon dioxide (CO2) and 16:8 light to dark cycle at fixed temperature. The research performed contained the following stages: 1) Growth monitoring (analysis of growth rate), 2) Microalgae harvesting (lab-scale lipid extraction), 3) Biodiesel production and 4) Determination of biodiesel quantity and quality. The results show that the total lipids (% dry weight biomass) from Scenedesmus dimorphus and Isochrysis aff. galbana cultures were found to be 15.87 and 42.65%, respectively. The obtained yields of the transesterification reactions were 87.4% (Scenedesmus dimorphus) and 94.6% (Isochrysis aff galbana). The methyl esters of Isochrysis aff. galbana contained higher percentage of saturated fatty acids than Scenedesmus dimorphus and its fatty acid composition improved the basic fuel properties. The overall finding of the study suggested that Isochrysis aff. galbana can be considered as more viable source for biodiesel production, in part due to the relative ease in producing a high oil yield.

CO2 Capture of the Gas Emission, Using a Catalytic Converter and Airlift Bioreactors with the Microalga Scenedesmus dimorphus

A process composed by a catalytic converter and three sequential Airlift photobioreactors containing the microalga Scenedesmus dimorphus was studied to capture CO2, NOx, and CO from emissions of a steam boiler which was burning diesel. The catalytic converter transformed to CO2 a maximum of 78% of the CO present in the combustion gas. The effects of shear rate, light intensity, and light/dark cycles on the biomass growth of the algae were studied. It was observed that at low shear rates (Re ≈ 3200), a high productivity of 0.29 gcel L−1 d−1 was obtained. When the microalga was exposed to 60.75 µmol·m−2·s−1 of intensity of light and a light/dark cycle of 16/8 h, a maximum productivity of 0.44 gcel L−1 d−1 and a maximum CO2 fixation rate 0.8 g CO2 L−1·d−1 were obtained. The maximum CO2 removal efficiency was 64.3%, and KLa for CO2 and O2 were 1.2 h−1 and 3.71 h−1 respectively.

Evaluación de carotenoides y lípidos en la microalga Scenedesmus dimorphus a escala laboratorio

Carotenoids are metabolites produced by microalgae that perform as accessory pigments in photosynthesis and as photoprotective molecules. In order to increase the accumulation of carotenoids in the microalga Scenedesmus dimorphus, salinity (NaCl and KNO3) and blue led light were evaluated as stress factors when reaching the stationary phase of culture growth in such microalga. After evaluation, the best of the two salts studied was KNO3 0.6M, since this culture reached the highest concentration of total carotenoids (0.3357±0.02 μg carotenoids mL-1), in contrast to 0.1791±0.01 µg mL-1 with NaCl 0.6 M. Subsequently, the process was scaled in an adapted container of 4 L, entering the stationary phase on day 12. On day 14 the KNO3 was added at 0.6 M; this experiment lasted 20 days of cell count, obtaining on the last day a total of 0,7395±0,05 μg of carotenoids mL-1 by means of spectrophotometry. Afterwards, drying of the culture with salinity was carried out, obtaining a dry weight of 5.7 g, with a productivity of 0.0927 g L-1d-1. Finally, through hplc chromatography, the lipid profile of the culture was analyzed, resulting in 21.1% mufas, 35.9% sfas, and 43% pufas (34% omega-6 and 8.9% omega-3). Based on the above, it was determined that salinity is a possible factor to increase in a greater proportion the concentration of lipids than that of carotenoids, specifically in a ratio of 1:2,500 carotenoids and lipids, respectively.

Stressing Algae for Biofuel Production: Biomass and Biochemical Composition of Scenedesmus dimorphus and Selenastrum minutum Grown in Municipal Untreated Wastewater

Biofuel production using microalgae is a renewable and environmental-friendly alternative to the use of fossil fuels. Microalgae storage lipids are promising resources for biofuel production. In this study, pure strains of the microalgae Scenedesmus dimorphus and Selenastrum minutum were grown in untreated municipal wastewater for six days under mixotrophic conditions. The algae strains were subjected to different stresses such as nutrient deprivation, and 5% (w/v) salinity to trigger lipid production and to study effect on FAME composition. The highest lipid concentrations were found in S. dimorphus (35 and 34%) and in S. minutum (40 and 39%) under nutrient deprivation and 5% salinity, respectively. On the one hand, salt stress decreased biomass production; on the other hand in both S. dimorphus and S. minutum salt stress significantly increased the concentration of saturated fatty acid (SFA) and it decreased the concentration of poly-unsaturated fatty acid (PUFA) contents, which are desirable for the production of good quality biofuel such as biodiesel. Hence our findings show how salt stress could clearly affect FAME composition in short time 1 to 3 days, greatly improving the FAME quality as source of biofuel.

Cultivation of Scenedesmus dimorphus using anaerobic digestate as a nutrient medium.

In this study, the microalga Scenedesmus dimorphus was cultivated phototrophically using unsterilized anaerobic digestate as a nutrient medium. A bench-scale experiment was conducted by inoculating the microalga S. dimorphus with 0.05-10% dilutions of the anaerobic digestate supernatant. It was found that 1.25-2.5% dilutions, which is equivalent to 50-100mgN/L total nitrogen concentrations and 6-12mg P/L total phosphorus concentrations, provided sufficient nutrients to maximize the growth rate along with achieving high concentrations of algal biomass. The microalgae cultivation was scaled up to 100L open raceway ponds, where the effect of paddlewheel mixing on the growth was investigated. It was concluded that 0.3m/s water surface velocity yielded the highest specific growth rate and biomass concentration compared to 0.1 and 0.2m/s. The microalga S. dimorphus was then cultivated in the raceway ponds using 2.5% diluted anaerobic digestate at 317 and 454μmol/(m2×s) average incident light intensities and 1.25% diluted anaerobic digestate at 234 and 384μmol/(m2×s) average incident light intensities. The maximum biomass concentration was 446mg/L which was achieved in the 2.5% dilution and 454μmol/(m2×s) light intensity culture. Moreover, nitrogen, phosphorus, and COD removal efficiencies from the nutrient media were 65-72, 63-100, and 78-82%, respectively, whereas ammonia was completely removed from all cultures. For a successful and effective cultivation in open raceway ponds, light intensity has to be increased considerably to overcome the attenuation caused by the algal biomass as well as the suspended solids from the digestate supernatant.

Fatty Acid Composition and Technological Quality of the Lipids Produced by the Microalga Scenedesmus Dimorphus 1237 as a Function of Culturing Conditions

Fatty Acid Composition and Technological Quality of the Lipids Produced by the Microalga Scenedesmus Dimorphus 1237 as a Function of Culturing Conditions

Effects of light condition in the continuous mass cultivation of microalgae Scenedesmus dimorphus

This study investigated the effects of the light conditions on the productivity of scenedesmus dimorphus in the continuous mass cultivation system. To compare the algal productivity according to the light conditions, S. dimorphus was cultivated continuously under the wide range of light intensity(200-600 PPFD) and various light wavelength(white light and red-blue mixed light). After 100 days of cultivation under the different light intensity, the productivity of S. dimorphus increased as light intensity decreased. So, the productivity was maximized as 100 mg/L/d when light intensity was 200 PPFD. In case of light wavelength, the productivity of S. dimorphus was enhanced about 20% with the white light compared to that of the red-blue mixed light. Consequently, the optimal light conditions for the continuous mass cultivation of S. dimorphus were 200 PPFD as light intensity and white light as light wavelength.

Using carbon dioxide to maintain an elevated oleaginous microalga concentration in mixed-culture photo-bioreactors

Microbial contamination of growth reactors is a major concern for microalgal biofuel production. In this study, the oleaginous, CO2-tolerant microalga Scenedesmus dimorphus was combined with a wastewater-derived microbial community and grown in replicated sequencing batch photobioreactors. The reactors were sparged with either ambient air or 20% v/v CO2. In the initial growth cycles, air and the 20% CO2 reactors were similar in terms of growth and microbial community structure. Beyond the fourth growth cycle, however, the ambient air reactors had larger decreases in cell density and growth rate, and increases in species richness and non-algal microorganisms compared to the 20% CO2 reactors. Both qPCR and rDNA sequence analyses demonstrated a greater loss in S. dimorphus enrichment in the ambient-air reactors compared to the 20% CO2 reactors. These results demonstrate that environmental parameters can be used to delay the adverse impacts of microbial contamination in open, mixed-culture microalgae bioreactors.

Biosorption Ability of Microalgae Scenedesmus dimorphus for Cr (VI) and Cd in Aqueous Solution

Biosorption Ability of Microalgae <i>Scenedesmus dimorphus</i> for Cr (VI) and Cd in Aqueous Solution

Development of microalga Scenedesmus dimorphus mutant with higher lipid content by radiation breeding.

In this study, a high lipid-accumulating mutant strain of the microalgae Scenedesmus dimorphus was developed via radiation breeding. To induce mutant strain, S. dimorphus was gamma-irradiated at doses from 100 to 800Gy, and then a mutant (Sd-Pm210) with 25% increased lipid content was selected using Nile red staining methodology. Sd-Pm210 showed morphological changes and had higher growth rate compared to the wild type. From random amplified polymorphic DNA analysis, partial genetic modifications were also observed in Sd-Pm210. In comparisons of lipid content between wild type and Sd-Pm210 using thin-layer chromatography, the content of triacylglycerol was markedly higher in the Sd-Pm210 strain. The total peak area of fatty acid methyl ester was shown to have about 1.4-fold increase in Sd-Pm210, and major fatty acids were identified as palmitic acid, oleic acid, linoleic acid, and linolenic acid. To define the metabolic changes in the mutant strain, 2-dimensional electrophoresis was conducted. Several proteins related to lipid synthesis and energy metabolisms were overexpressed in the mutant strain. These results showed that radiation breeding can be utilized for the development of efficient microalgae strains for biofuel production.

A Single-Step Method for Rapid Extraction of Total Lipids from Green Microalgae

Microalgae produce a wide range of lipid compounds of potential commercial interest. Total lipid extraction performed by conventional extraction methods, relying on the chloroform-methanol solvent system are too laborious and time consuming for screening large numbers of samples. In this study, three previous extraction methods devised by Folch et al. (1957), Bligh and Dyer (1959) and Selstam and Öquist (1985) were compared and a faster single-step procedure was developed for extraction of total lipids from green microalgae. In the single-step procedure, 8 ml of a 2∶1 chloroform-methanol (v/v) mixture was added to fresh or frozen microalgal paste or pulverized dry algal biomass contained in a glass centrifuge tube. The biomass was manually suspended by vigorously shaking the tube for a few seconds and 2 ml of a 0.73% NaCl water solution was added. Phase separation was facilitated by 2 min of centrifugation at 350 g and the lower phase was recovered for analysis. An uncharacterized microalgal polyculture and the green microalgae Scenedesmus dimorphus, Selenastrum minutum, and Chlorella protothecoides were subjected to the different extraction methods and various techniques of biomass homogenization. The less labour intensive single-step procedure presented here allowed simultaneous recovery of total lipid extracts from multiple samples of green microalgae with quantitative yields and fatty acid profiles comparable to those of the previous methods. While the single-step procedure is highly correlated in lipid extractability (r2 = 0.985) to the previous method of Folch et al. (1957), it allowed at least five times higher sample throughput.

Selection and evaluation of CO2 tolerant indigenous microalga Scenedesmus dimorphus for unsaturated fatty acid rich lipid production under different culture conditions

Five indigenous microalgal strains of Scenedesmus, Chlorococcum, Coelastrum, and Ankistrodesmus genera, isolated from Indian fresh water habitats, were studied for carbon-dioxide tolerance and its effect on growth, lipid and fatty acid profile. Scenedesmus dimorphus strain showed maximum growth (1.5 g/L) and lipid content (17.83% w/w) under CO2 supplementation, hence selected for detailed evaluation. The selected strain was alkaline adapted but tolerated (i) wide range of pH (5-11); (ii) elevated salinity levels (up to 100 mM, NaCl) with low biomass yields and increased carotenoids (19.34 mg/g biomass); (iii) elevated CO2 levels up to 15% v/v with enhancement in specific growth rate (0.137 d(-1)), biomass yield (1.57 g/L), lipid content (19.6% w/w) and CO2 biofixation rate (0.174 g L(-1) d(-1)). Unsaturated fatty acid content (alpha linolenic acid) increased with CO2 supplementation in the strain.

Biodiesel by Hydroesterification of Oil from the Microalgae &lt;i&gt;Scenedesmus dimorphus&lt;/i&gt;

In this work we investigated the synthesis of methyl esters (biodiesel) of oil obtained from the microalgae Scenedesmus dimorphus through the hydro-esterification process (esterification process preceded by hydrolysis) as possible alternative for conventional processes. There is interest to develop new raw materials and reactions processes that favors the maintenance of biodiesel in the global energy matrix. Keywords: Biodiesel, hydroesterification, microalgae scenedesmus dimorphus.

Effects of different nitrogen, phosphorus, and iron concentrations and salinity on lipid production in newly isolated strain of the tropical green microalga, Scenedesmus dimorphus KMITL

The fatty acid composition, the effect of different concentrations of nitrogen (16.5-344 mg L−1), phosphorus (9–45 mg L−1), iron (9–45 mg L−1) and salinity levels (0–20 psu) on lipid production in the green microalga Scenedesmus dimorphus KMITL, a new strain isolated from a tropical country, Thailand, were studied. The alga was isolated from a freshwater fish pond, and cultured in Chlorella medium by varying one parameter at a time. The main fatty acid composition of this strain was C16–C18 (97.52 %) fatty acids. A high lipid content was observed in conditions of 16.5 mg L−1-N, or 22 mg L−1-P, or 45 mg L−1-Fe, or 5 psu salinity, which accumulated lipids to 20.3 ± 0.4, 19.4 ± 0.2, 24.7 ± 0.5, and 14.3 ± 0.2 % of algal biomass, respectively. Increasing lipid content and lipid productivity was noted when the alga was cultured under high iron concentration and high salinity, as well as under reduced phosphorus conditions, whereas nitrogen limitation only resulted in an increased lipid content.

A flexible culture process for production of the green microalga Scenedesmus dimorphus rich in protein, carbohydrate or lipid

Microalgae have the ability to undergo programmatic changes in photosynthetic carbon partitioning and thus cellular biochemical composition, particularly in the relative amounts of crude protein, lipids, and carbohydrate, in response to changes in environmental and culture conditions. In this study, a novel strategy that employs a single microalgal strain Scenedesmus dimorphus grown in a single cultivation platform to produce protein-, carbohydrate- or lipid-rich biomass, as so desired, was introduced. With the combined manipulation of nitrogen availability and light intensity and cell inoculation density, it was successfully demonstrated that highest yields for protein and carbohydrate were 0.2 and 0.7gL−1d−1, respectively, which could be obtained in early stages of cultivation, while the highest yield for lipid, 0.17gL−1d−1, occured in a late stage of cultivation.

Lipid Extraction from Microalgae &lt;i&gt;Scendesmus dimorphus&lt;/i&gt; by Wet-Milling Process Using Response Surface Approach

The objective of this study was to understand the effect of biomass concentration (BC), milling times (MT) and volumetric hexane to water ratio (HWR) on lipid recovery rate of microalgae Scenedesmus dimorphus in the wet milling process. A second-order response surface regression model (R2&gt;95%) was developed based on a three-variable five-level experiment using the Central Composite Design method. Modeling results indicated that HWR (Pr&lt;0.001) and BC (Pr&lt;0.01) significantly affected lipid recovery rate. The optimum settings were found to be 21.2 g l-1BC, 4 MT and 0.70 HWR, at which 98.5% of lipids were recovered. The results indicated that the wet grinding mill was effective in lipid recovery fromS. dimorphus.