Search

• Bioremediation with flue gas CO 2 utilization potential of Chlorella was tested. • Wastewater cocktail based biodiesel and lutein production in open raceway ponds. • 100% nitrogenous substance with 85–91% carbon-phosphorus remediation were obtained. • Biomass and lutein productivity of 6.21 ± 0.16, 1.2 ± 0.08 g m−2 day−1 was achieved. • Two-fold increase in lipid content and 80.74 ± 0.07 mg L−1 day−1 CO 2 was utilized. We evaluated wastewater remediation and CO 2 utilization potential of Chlorella minutissima from flue gas in a raceway pond, while synthesizing lutein and lipid for potential healthcare and biofuel application. A mix of 20% kitchen waste, 10 g L−1 of poultry litter waste and 5% flue gas was maintained while cultivating the microalga. Complete removal of nitrate, nitrite and ammonium, 85% carbon and 91% phosphorus was observed. An average areal biomass productivity of 4.06 ± 0.12 g m−2 day−1 with a specific growth rate of 0.34 ± 0.03 day−1 was observed within 9 days. Biomass productivity of 6.21 ± 0.16 g m−2 day−1 with a specific growth rate of 0.34 ± 0.03 day−1 was achieved during winter. Furthermore, lipid content with appropriate fatty acid composition 1.04:1 (saturation:unsaturation) increased from 25% to 58%. Additionally, lutein productivity of 1.2 ± 0.08 mgL−1 day−1, while utilizing 80.74 ± 0.07 mg L−1 day−1 of CO 2 from 5% flue gas was obtained. [ABSTRACT FROM AUTHOR]

Switching cultivation (mixotrophic-heterotrophic, 12 h:12 h) of Heynigia riparia SX01 was studied, the maximum biomass concentration of 3.55 g L −1 and lipid yield of 1.45 g L −1 were achieved after 8 days cultivation. The extracellular polymeric substance (EPS) was developed as co-product. Addition of MgSO 4 could enhance the production of EPS. The highest amount of 0.60 g L −1 EPS was obtained with the addition of 2 g L −1 MgSO 4 , the self-flocculation efficiency was as high as 83% at this condition. The total lipid and lipid fractions did not show differences with extra MgSO 4 . Based on the above results, a new biodiesel production model was proposed: culturing Heynigia riparia SX01 with extra 2 g L −1 MgSO 4 by switching cultivation and using self flocculation to collect microalgae for biodiesel production, while EPS was collected as valuable co-products. [ABSTRACT FROM AUTHOR]

To improve the biomass yield and lipid productivity, two desert microalgae, Desmodesmus sp. S81 and G41 were induced mutagenesis by Ethylmethane sulfonate (EMS), and obtained two potential mutants, Desmodesmus sp. S5 and G3 from the mutagenic clones for their greatly promoted biomass and lipid production. The results showed that the biomass yield, lipid content and lipid productivity of the mutant strains S5 and G3 were 778.10 mg·L −1 , 48.41% and 19.83 mg·L −1 ·d −1 , 739.52 mg·L −1 , 46.01%, and 17.92 mg·L −1 ·d −1 , respectively, which presented the increment of 45.50%, 8.00% and 74.24%, 20.67%, 10.35% and 55.77% than those of S81 and G41. Comparing with the wild strains, the mutants showed reduced PUFAs and glycol lipids, elevated MUFAs and neutral lipids contents, which were appropriate for biodiesel production. [ABSTRACT FROM AUTHOR]

The development of a culture system for Chlorella sp. GD to efficiently produce biomass and oil for biodiesel production was investigated. Chlorella sp. GD was cultivated with 0%, 25%, 50%, 75% and 100% piggery wastewater (diluted by medium) at 300 μmol m −2 s −1 , a 2% CO 2 aeration rate of 0.2 vvm and 26 ± 1 °C; after a 10-day culture in batch cultures, the maximum specific growth rate and biomass productivity of the microalga obtained in 100% piggery wastewater were 0.839 d −1 and 0.681 g L −1 d −1 , respectively. The highest lipid content and lipid productivity were 29.3% and 0.155 g L −1 d −1 at 25% wastewater, respectively. In semi-continuous cultures, the biomass and lipid productivities with 25–75% wastewater ratios were greater than 0.852 and 0.128 g L −1 d −1 , respectively. These results show that Chlorella sp. GD grows efficiently in piggery wastewater, and that a stable growth performance was achieved for long-term microalgal cultivation in a semi-continuous culture. [ABSTRACT FROM AUTHOR]

Abstract: A green microalgae, named as Ettlia texensis was obtained from local freshwater in Turkey. The effects of autotrophic, photoheterotrophic and heterotrophic cultivations on biomass and lipid production were studied. Searching the preferences of the carbon and nitrogen source revealed that this strain could grow photoheterotrophically well with glucose and yeast extract. In the optimized medium, the highest biomass productivity and total lipid content achieved were 0.97g/Ld and 26% of dry weight basis, respectively. Moreover, the major fatty acid methyl esters were C16:0; C18:1; C18:2 and C18:3. In a scale-up attempt, productions were accomplished in a 3L stirred tank bioreactor. The final biomass and lipid productivities obtained in bioreactor with 250rpm agitation rate were 0.92g/Ld and 322mg/Ld, respectively. The biochemical compositions were monitored simultaneously by the FTIR spectroscopy during the production in bioreactor. E. texensis could be potent candidate for commercial production in the bioreactor photoheterotrophically. [Copyright &y& Elsevier]

Abstract: To augment biomass and lipid productivities of heterotrophic cultured microalgae Chlorella sorokiniana, the influence of environmental temperature and medium factors, such as carbon source, nitrogen source, and their initial concentrations was investigated in this study. The microalga C. sorokiniana could tolerate up to 42°C and showed the highest growth rate of 1.60d−1 at 37°C. The maximum dry cell weight (DCW) and corresponding lipid concentration was obtained with 80gL−1 of initial glucose and 4gL−1 of initial KNO3 at 37°C. In 5-L batch fermentation, the DCW increased dramatically from 0.9gL−1 to 37.6gL−1 in the first 72h cultivation, with the DCW productivity of 12.2gL−1 d−1. The maximum lipid content of 31.5% was achieved in 96h and the lipid productivity was 2.9gL−1 d−1. The results showed C. sorokiniana could be a promising strain for biofuel production. [Copyright &y& Elsevier]

Abstract: In order to develop feasible production processes for microalgal biodiesel, the isolation of high neutral lipid producing microalgae is crucial. Since the established Nile Red (NR) method for detection of intracellular lipids has been successful only for some microalgae, a more broadly applicable detection method would be desirable. Therefore, BODIPY 505/515, a lipophilic bright green fluorescent dye was tested for detection of intracellular lipids in Chlorella vulgaris, Dunaliella primolecta and Chaetoceros calcitrans. An optimum concentration of 0.067μgml−1 was determined for lipid staining in the microalgae. Compared to NR, BODIPY 505/515 was more effective in staining microalgae and showed resistance to photobleaching, maintaining its fluorescence longer than 30min. [Copyright &y& Elsevier]

Abstract: A novel cultivation strategy called “sequential heterotrophy–dilution–photoinduction” was developed for efficient algal biomass and lipid production. Three Chlorella species were first cultivated heterotrophically to achieve high cell density, then the broth was diluted to suitable concentration (2–5g/L) and transferred to light environment for photoinduction. With this strategy, the Chlorella intracellular protein and chlorophyll increased rapidly to 50.87% and 32.97mg/g by a 12-h illumination, which were close to the level of cells cultivated photoautotrophically. Moreover, the lipid contents were increased by 84.57%, 70.65% and 121.59% within 24-h photoinduction for C. vulgaris, C. pyrenoidosa and C. ellipsoidea, respectively. Maximum lipid content as 26.11% of biomass and maximum lipid productivity of 89.89mg/L/d was both accomplished by C. pyrenoidosa. Further outdoor experiments showed consistent patterns. Therefore, the proposed strategy provided an effective approach for microalgal biomass production to meet the urgent need for both health food and biodiesel. [Copyright &y& Elsevier]

Abstract: Three different strains of colonial green alga Botryococcus bruanii Kutz. AP103, AP104 and AP105 were isolated from the freshwater lake Kolleru, Andhra Pradesh, India. The morphological features of these three isolates were studied under laboratory conditions. Molecular identification of the strains was carried out using 18S rRNA analysis and their systematic position was confirmed to species level as B. braunii. Among these isolates, B. braunii AP103 recorded highest biomass concentration of 1.7±0.12gL−1, 17% lipids, 17% proteins, 32% carbohydrates and 13% hydrocarbons under laboratory condition. Under open raceway pond AP103 produced a biomass concentration of 1.8±0.13gL−1, 19% lipids, 33% carbohydrates, 18% proteins and 11% hydrocarbons. The hydrocarbons profile showed the presence of heptadecane (34%) and hexadecane (12.5%). Oleic (25.7%), linolenic (34.26%) and palmitic (9.42%) acids were the major fatty acids present in the lipids extracted from AP103. [Copyright &y& Elsevier]

Abstract: To reduce the cost of algal biomass production, mathematical model was developed for the first time to describe microalgae growth, lipid production and glycerin consumption under photoheterotrophic conditions based on logistic, Luedeking–Piret and Luedeking–Piret-like equations. All experiments were conducted in a 2L batch reactor without considering CO2 effect on algae’s growth and lipid production. Biomass and lipid production increased with glycerin as carbon source and were well described by the logistic and Luedeking–Piret equations respectively. Model predictions were in satisfactory agreement with measured data and the mode of lipid production was growth-associated. Sensitivity analysis was applied to examine the effects of certain important parameters on model performance. Results showed that S0, the initial concentration of glycerin, was the most significant factor for algae growth and lipid production. This model is applicable for prediction of other single cell algal species but model testing is recommended before scaling up the fermentation of process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Actinomycete co-culture successfully enhanced both microalgal biomass and lipid. • Piscicocus intestinalis WA3 produced high algal growth-promoting agents. • Microbial lipids are composed of C16-C20 fatty acids with good fuel properties. • Biogas effluent can be used as cost-effective media for actinomycete co-culture. In this study, an innovative approach to enhance the production of microalgal biomass and lipid as a promising sustainable feedstock for biodiesel was proposed using an actinomycetes co-culture with microalgae in the biogas digestate effluent (BDE) that can be employed as an environmentally friendly and cost-effective strategy. Among tested actinomycete isolates, Piscicocus intestinalis WA3 produced indole-3-acetic acid and siderophores as algal growth promoting agents and showed effective lipid accumulation with satisfying fatty acids composition. During co-cultivation of P. intestinalis WA3 with microalga Tetradesmus obliquus AARL G022 in the BDE, biomass production, chlorophyll a content, and lipid productivity were significantly increased by 1.30 folds, 1.39 folds, and 1.55 folds, respectively, compared to microalgae monoculture. The accumulated lipids contained long-chain fatty acids with better fuel properties that could potentially be used as biodiesel feedstock. The overall results evidenced that actinomycete co-culture would contribute greatly to the cost-effective production of environmental-friendly microbial-based biofuel. [ABSTRACT FROM AUTHOR]

Abstract: Microalgae have the ability to grow rapidly, synthesize and accumulate large amounts (approximately 20–50% of dry weight) of lipids. A successful and economically viable algae based oil industry depends on the selection of appropriate algal strains. In this study ten species of microalgae were prospected to determine their suitability for oil production: Chaetoceros gracilis, Chaetoceros mulleri, Chlorella vulgaris, Dunaliella sp., Isochrysis sp., Nannochloropsis oculata, Tetraselmis sp., Tetraselmis chui, Tetraselmis tetrathele and Thalassiosira weissflogii. The study was carried out in 3L glass flasks subjected to constant aeration and controlled artificial illumination and temperature at two different salinities. After harvesting, the extraction of oil was carried out using the Bligh and Dyer method assisted by ultrasound. Results showed that C. gracilis presented the highest oil content and that C. vulgaris presented the highest oil production. [Copyright &y& Elsevier]

• AGP locus in Tetraslemis sp. was mutated by CRISPR-Cas9 RNP. • AGP mutants showed enhanced lipid production and the absence of starch synthesis. • Fatty acids in AGP mutants increased by 274% and 314% compared to that in wild type. • AGP mutants showed 2.3- and 2.7-fold higher lipid productivity than the wild type. A marine green microalga, Tetraselmis sp., has been studied for the production of biomass and lipids in seawater culture. Since carbohydrate and lipid biosynthesis are competitive metabolic pathways, we attempted to increase lipid synthesis in Tetraselmis by inhibiting carbohydrate synthesis. The main regulatory enzyme in the starch synthesis pathway is ADP-glucose pyrophosphorylase (AGP). AGP loss-of-function mutants were developed using the CRISPR-Cas9 ribonucleoprotein (RNP) delivery system. AGP mutants showed a slight decrease in growth. However, the lipid content in two AGP mutants was significantly enhanced by 2.7 and 3.1 fold (21.1% and 24.1% of DCW), respectively, compared to that in the wild type (7.68% of DCW) under nitrogen starvation. This study is an example of metabolic engineering by genetic editing using the CRISPR-Cas9 RNP method in marine green microalgae. Consequently, starchless Tetraselmis mutants might be considered potential producers of lipids in seawater cultures. [ABSTRACT FROM AUTHOR]

• Algae were grown in walnut shell extracts (WSE) supplemented with carbon dioxide. • CO 2 significantly boosted the biomass and lipid productivities of algae under WSE cultivation. • A combined strategy was developed for WSE utilization and biofuel production. Microalgae are a promising biofuel resource, but their high cost and low productivity hinder their commercial applications. In the present study, Monoraphidium sp. QLZ-3 was cultivated in walnut shell extracts (WSE) supplemented with carbon dioxide (CO 2). Biomass was enhanced from 0.40 g L−1 to 1.18 g L−1, and lipid content reached 49.54% in WSE-12% CO 2 media. Biomass and lipid productivity reached 196.88 and 97.52 mg L−1 d−1, which were 1.33- and 1.57-fold higher than those of the control, respectively. The amount of carbohydrates increased, but the protein contents decreased. Furthermore, the application of CO 2 promoted nutrient and polyphenol absorption and upregulated the expression levels of lipid biosynthetic genes of this WSE-cultivated alga. These results indicated that coupling WSE and CO 2 could be an efficient strategy to enhance biofuel production by microalgae. [ABSTRACT FROM AUTHOR]