Downstream processing of algal polyunsaturated fatty acids

Advancements in sustainable production of biofuel by microalgae: Recent insights and future directions

Microalgae is considered as sustainable and viable feedstock for biofuel production due to its significant advantages over terrestrial plants. Algal biofuels have received significant attention among researchers and energy experts owing to an upsurge in global energy issues emanating from depletion in fossil fuel reserves increasing greenhouse gases emission conflict among agricultural crops, traditional biomass feedstock, and potential futuristic energy security. Further, the exploration of value-added microalgae as sustainable and viable feedstock for the production of variety of biofuels such as biogas, bio-hydrogen, bioethanol, and biodiesel are addressed. Moreover, the assessment of life-cycle, energy balance, and environmental impacts of biofuel production from microalgae are briefly discussed. The present study focused on recent advancements in synthetic biology, metabolic engineering tools, algal bio refinery, and the optimization of algae growth conditions. This paper also elucidates the function of microalgae as bio refineries, the conditions of algae-based cultures, and other operational factors that must be adjusted to produce biofuels that are price-competitive with fossil fuels.

Microalgal Biomass as Feedstock for Bacterial Production of PHA: Advances and Future Prospects

The search for biodegradable plastics has become the focus in combating the global plastic pollution crisis. Polyhydroxyalkanoates (PHAs) are renewable substitutes to petroleum-based plastics with the ability to completely mineralize in soil, compost, and marine environments. The preferred choice of PHA synthesis is from bacteria or archaea. However, microbial production of PHAs faces a major drawback due to high production costs attributed to the high price of organic substrates as compared to synthetic plastics. As such, microalgal biomass presents a low-cost solution as feedstock for PHA synthesis. Photoautotrophic microalgae are ubiquitous in our ecosystem and thrive from utilizing easily accessible light, carbon dioxide and inorganic nutrients. Biomass production from microalgae offers advantages that include high yields, effective carbon dioxide capture, efficient treatment of effluents and the usage of infertile land. Nevertheless, the success of large-scale PHA synthesis using microalgal biomass faces constraints that encompass the entire flow of the microalgal biomass production, i.e., from molecular aspects of the microalgae to cultivation conditions to harvesting and drying microalgal biomass along with the conversion of the biomass into PHA. This review discusses approaches such as optimization of growth conditions, improvement of the microalgal biomass manufacturing technologies as well as the genetic engineering of both microalgae and PHA-producing bacteria with the purpose of refining PHA production from microalgal biomass.

Lipids from Microalgae for Cosmetic Applications

In recent years, there has been considerable interest in using microalgal lipids in the food, chemical, pharmaceutical, and cosmetic industries. Several microalgal species can accumulate appreciable lipid quantities and therefore are characterized as oleaginous. In cosmetic formulations, lipids and their derivatives are one of the main ingredients. Different lipid classes are great moisturizing, emollient, and softening agents, work as surfactants and emulsifiers, give consistence to products, are color and fragrance carriers, act as preservatives to maintain products integrity, and can be part of the molecules delivery system. In the past, chemicals have been widely used but today’s market and customers’ demands are oriented towards natural products. Microalgae are an extraordinary source of lipids and other many bioactive molecules. Scientists’ attention to microalgae cultivation for their industrial application is increasing. For the high costs associated, commercialization of microalgae and their products is still not very widespread. The possibility to use biomass for various industrial purposes could make microalgae more economically competitive.

Microalgae Encapsulation Systems for Food, Pharmaceutical and Cosmetics Applications

Microalgae are microorganisms with a singular biochemical composition, including several biologically active compounds with proven pharmacological activities, such as anticancer, antioxidant and anti-inflammatory activities, among others. These properties make microalgae an interesting natural resource to be used as a functional ingredient, as well as in the prevention and treatment of diseases, or cosmetic formulations. Nevertheless, natural bioactives often possess inherent chemical instability and/or poor solubility, which are usually associated with low bioavailability. As such, their industrial potential as a health-promoting substance might be severely compromised. In this context, encapsulation systems are considered as a promising and emerging strategy to overcome these shortcomings due to the presence of a surrounding protective layer. Diverse systems have already been reported in the literature for natural bioactives, where some of them have been successfully applied to microalgae compounds. Therefore, this review focuses on exploring encapsulation systems for microalgae biomass, their extracts, or purified bioactives for food, pharmaceutical, and cosmetic purposes. Moreover, this work also covers the most common encapsulation techniques and types of coating materials used, along with the main findings regarding the beneficial effects of these systems.

Lipid Extraction Maximization and Enzymatic Synthesis of Biodiesel from Microalgae

Microalgae has received overwhelming attention worldwide as a sustainable source for energy generation. However, the production of biofuel from microalgae biomass consists of several steps, of which lipid extraction is the most important one. Because of the nature of feedstock, extraction needs special attention. Three different methods were studied to extract algal oil from two different algae variant, Chlorella sp. and Spirulina sp. The highest percentage oil yield was obtained by ultrasonication (9.4% for Chlorella sp., 6.6% for Spirulina sp.) followed by the Soxhlet and solvent extraction processes. Ultrasonication and Soxhlet extraction processes were further optimized to maximize oil extraction as solvent extraction was not effective in extracting lipid. For ultrasonication, an amplitude of 90% recorded the highest percentage yield of oil for Spirulina sp. and a 70% amplitude recorded the highest percentage yield of oil for Chlorella sp. On the other hand, for Soxhlet extraction, a combination of chloroform, hexane, and methanol at a 1:1:1 ratio resulted in the highest yield of algal oil. Afterward, the crude algae oil from the ultrasonication process was transesterified for 5 h using an immobilized lipase (Novozyme 435) at 40 °C to convert triglycerides into fatty acid methyl ester and glycerol. Thus, ultrasonic-assisted lipid extraction was successful in producing biodiesel from both the species.

Switchable solvent N, N, N', N'-tetraethyl-1, 3-propanediamine was dissociated into cationic surfactant to promote cell disruption and lipid extraction from wet microalgae for biodiesel production

Switchable solvent N, N, N', N'-tetraethyl-1,3-propanediamine (TEPDA) was proposed to extract lipids from wet Nannochloropsis oceanica with a 5% higher extraction efficiency than chloroform-methanol. It was found that TEPDA acted mainly as an organic solvent to soften and dissolve lipids, while a small amount of TEPDA was dissociated into tertiary amine ion, i.e.,(C₂H₅)₂N-(CH₂)₃-NH⁺(C₂H₅)₂. This cation acted as a surfactant to promote cell disruption and lipid separation. With moisture increasing from 0 to 84 wt%, more TEPDA was dissociated into cationic surfactant to induce local rearrangement of phospholipid bilayers in cell membranes through electrostatic interaction, resulting in the fractal dimension of disrupted cells increased from 1.49 to 1.66. Accordingly, the yield of fatty acid methyl ester (FAME) through transesterification of lipids extracted with TEPDA increased by 9%, while FAME yield from lipids extracted with chloroform and n-hexane decreased by 41% and 65%, respectively.

Analysis of Scientific Research Driving Microalgae Market Opportunities in Europe

A bibliographic database of scientific papers published by authors affiliated to research institutions worldwide, especially focused in Europe and in the European Atlantic Area, and containing the keywords "microalga(e)" or "phytoplankton" was built. A corpus of 79,020 publications was obtained and analyzed using the Orbit Intellixir software to characterize the research trends related to microalgae markets, markets opportunities and technologies that could have important impacts on markets evolution. Six major markets opportunities, the production of biofuels, bioplastics, biofertilizers, nutraceuticals, pharmaceuticals and cosmetics, and two fast-evolving technological domains driving markets evolution, microalgae harvesting and extraction technologies and production of genetically modified (GM-)microalgae, were highlighted. We here present an advanced analysis of these research domains to give an updated overview of scientific concepts driving microalgae markets.

Spectral profiles of commercial omega-3 supplements: an exploratory analysis by ATR-FTIR and 1H NMR

Most of the population is dependent on supplemental products to reach the recommended level of omega-3 polyunsaturated fatty acid (ω-3 PUFA) intake. Thus, knowledge about the quality of ω-3 supplements is important for their safe consumption. In this work, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopy were applied to assess the quality of fourteen commercial ω-3 supplements. Using ATR-FTIR data, we could identify whether ω-3 PUFA was esterified as either triacylglyceride (71%) or ethyl (29%) esters in ω-3 supplements. The type of esterification is rarely included in the product labels, although the consumer should have the right to choose which form of the supplement to consume. On the other hand, ¹H NMR spectra were useful to determine the relative concentration of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, and ω-3 PUFA in these commercial samples. Ethyl esters have higher concentrations of unsaturated fatty acids. The NMR results showed a good agreement between the obtained and declared DHA and EPA amounts on the product labels, except for one sample whose high level of ω-3 PUFA indicated it to be a vegetable oil-enriched supplement. Moreover, ω-3 supplements from Schizochytrium sp. microalgae oil revealed higher levels of DHA and ω-3 PUFA, but lower levels of EPA than fish oil. These findings indicate the need for a constant assessment of the quality of commercial products whose ATR-FTIR spectra could be routinely used for the evaluation of PUFA esterification, and NMR analysis could be used to provide advanced quantitative information on commercial ω-3 supplements.

Outdoor cultivation of the green microalga Chlorella vulgaris under stress conditions as a feedstock for biofuel

The present work investigated the potential of the green alga Chlorella vulgaris to produce high-quality biofuel under culture stress conditions. The cultivation was carried out in a 1000 l open plate tank system, which provides biomass yields comparable to open pond systems, but with less area needed. Algal biomass and lipid content were measured repeatedly. We compared the two solvent systems n-hexane and hexane/isopropanol (HIP) for extraction efficiency of lipids and applied three different extraction methods Soxhlet, soaking, and soaking followed by Soxhlet (soak-Sox). The combination of the HIP solvent and the soak-Sox provided the highest lipid yield (15.8 ± 0.174). Volumetric biomass and lipid productivity were 0.201 g l^-1 day^-1 and 31.71 mg l^-1 day^-1, respectively, whereas areal biomass and lipid productivity were 25.73 g m^-2 day^-1 and 4.066 g m^-2 day^-1, respectively. The fatty acid profile by means of gas chromatography resulted in seven fatty acids from C₁₂ to C₁₈. The most abundant fatty acid methyl esters (FAMES) were palmitic (C16:0), oleic (C18:1), and stearic (C18:0) acids. Lipid synthesis enhanced by optimizing the Kuhl growth medium with replacing nitrate by urea (50% N compared to the original recipe) increased salt content (10 g/l NaCl), ferrous sulfate (0.5 g/l), and sodium acetate addition (1 g/l). With regard to density, kinematic viscosity, gravity, pour point, flash point, and cetane number, the Chlorella-biodiesel comply with ASTM and EN standards thus pointing at the high potential of lipids synthesized by Chlorella as a feedstock for biodiesel production.

Production of Lipids and Proteome Variation in a Chilean Thraustochytrium striatum Strain Cultured under Different Growth Conditions

Total lipids and docosahexaenoic acid (DHA) production by a Chilean isolated thraustochytrid were evaluated under different growth conditions in shake flasks. The analyzed strain was identified as Thraustochytrium striatum according to an 18S rRNA gene sequence analysis. The strain (T. striatum AL16) showed negligible growth in media prepared with artificial seawater at concentrations lower than 50% v/v and pH lower than 5. Maltose and starch were better carbon sources for growth than glucose. DHA content of the biomass grown with maltose (60 g L^-1) was doubled by increasing the agitation rate from 150 to 250 rpm. The DHA (0.8-6%) and eicosapentaenoic acid (0.2-21%) content in the total lipids varied depending on culture conditions and culture age. Lipid and DHA concentration increased (up to 5 g L^-1 and 66 mg L^-1, respectively) by regularly feeding the culture with a concentrated starch solution. Carotenoid accumulation was detected in cells grown with maltose or starch. Contrasting conditions of starch and glucose cultures were selected for comparative proteomics. Total protein extracts were separated by two-dimensional gel electrophoresis; 25 spots were identified using ESI-MS/MS. A protein database (143,006 entries) for proteomic interrogation was generated using de novo assembling of Thraustochytrium sp. LLF1b - MMETSP0199_2 transcriptome; 18 proteins differentially expressed were identified. Three ATP synthases were differentially accumulated in cultures with glucose, whereas malate dehydrogenase was more abundant in cells cultured with starch.

Lipid Extraction from Spirulina sp. and Schizochytrium sp. Using Supercritical CO2 with Methanol

Microalgae are one of the most promising feedstocks for biodiesel production due to their high lipid content and easy farming. However, the extraction of lipids from microalgae is energy intensive and costly and involves the use of toxic organic solvents. Compared with organic solvent extraction, supercritical CO₂ (SCCO₂) has demonstrated advantages through lower toxicity and no solvent-liquid separation. Due to the nonpolar nature of SCCO₂, polar organic solvents such as methanol may need to be added as a modifier in order to increase the extraction ability of SCCO₂. In this paper, pilot scale lipid extraction using SCCO₂ was studied on two microalgae species: Spirulina sp. and Schizochytrium sp. For each species, SCCO₂ extraction was conducted on 200 g of biomass for 6 h. Methanol was added as a cosolvent in the extraction process based on a volume ratio of 4%. The results showed that adding methanol in SCCO₂ increased the lipid extraction yield significantly for both species. Under an operating pressure of 4000 psi, the lipid extraction yields for Spirulina sp. and Schizochytrium sp. were increased by 80% and 72%, respectively. It was also found that a stepwise addition of methanol was more effective than a one-time addition. In comparison with Soxhlet extraction using methylene chloride/methanol (2:1, v/v), the methanol-SCCO₂ extraction demonstrated its high effectiveness for lipid extraction. In addition, the methanol-SCCO₂ system showed a high lipid extraction yield after increasing biomass loading fivefold, indicating good potential for scaling up this method. Finally, a kinetic study of the SCCO₂ extraction process was conducted, and the results showed that methanol concentration in SCCO₂ has the strongest influence on the lipid extraction yield.

PUFAs and PUAs production in three benthic diatoms from the northern Adriatic Sea

The production of polyunsaturated aldehydes (PUAs) has been reported by many planktonic diatoms, where they have been implicated in deleterious effects on copepod reproduction and growth of closeby microbes or suggested as infochemicals in shaping plankton interactions. This study investigates the production of PUAs by diatoms commonly occurring in the microphytobenthic communities in temperate regions: Tabularia affinis, Proschkinia complanatoides and Navicula sp. Results highlight the production of PUAs by the three benthic diatoms during stationary and decline phases, with intracellular concentrations from 1.8 to 154.4 fmol cell^-1, which are within the range observed for planktonic species. The existence of a large family of PUAs, including some with four unsaturations, such as decatetraenal, undecatetraenal and tridecatetraenal, was observed. Since particulate and dissolved PUAs were positively correlated, together with cell lysis, equivalent concentrations may be released during late growth stages, which may affect benthic invertebrates grazing on them and other microalgae.

Simultaneous cell disruption and lipid extraction in a microalgal biomass using a nonpolar tertiary amine

A simultaneous cell disruption and lipid extraction method is developed for microalgal biodiesel production using a triethylamine/methanol solvent system. Individually, the pure solvents, i.e. triethylamine and methanol, do not exhibit significant enhancement in lipid extraction, but a 3:7 (v/v) triethylamine/methanol mixture exhibits the highest lipid extraction, corresponding to 150% of the conventional chloroform/methanol (2:1, v/v) solvent extraction. This extraction is equivalent to 92.5% of the total lipids, even when extracted from a wet microalgal biomass with a water content of 80%. The cell surfaces of the microalgae are significantly disrupted without using additional cell disruption reagents and without requiring energy-intensive equipment. The lipid mass transfer coefficient is 1.6 times greater than that of the chloroform/methanol solvent system. It is clearly demonstrated that triethylamine and methanol cooperate well for the cell disruption and lipid extraction.

A novel microalgal lipid extraction method using biodiesel (fatty acid methyl esters) as an extractant

Although microalgae are considered promising renewable sources of biodiesel, the high cost of the downstream process is a significant obstacle in large-scale biodiesel production. In this study, a novel approach for microalgal biodiesel production was developed by using the biodiesel as an extractant. First, wet microalgae with 70% water content were incubated with a mixture of biodiesel/methanol and penetration of the mixture through the cell membrane and swelling of the lipids contained in microalgae was confirmed. Significant increases of lipid droplets were observed by confocal microscopy. Second, the swelled lipid droplets in microalgae were squeezed out using mechanical stress across the cell membrane and washed with methanol. The lipid extraction efficiency reached 68%. This process does not require drying of microalgae or solvent recovery, which the most energy-intensive step in solvent-based biodiesel production.

Production of methyl ester from two microalgae by two-step transesterification and direct transesterification

The efficiency of oil extraction from Chlorella sp. and Scenedesmus sp. using different cell disruption and solvent system was investigated. The ultrasound cell disruption method showed the maximum oil extraction in both algae. Oil extraction with hexane resulted in maximum oil yield for both algae. The kinetic parameters were studied and the extraction followed the first-order kinetics. The activation energy and thermodynamic activation parameters were calculated for both microalgae and the results suggested that the extraction was endothermic, irreversible and spontaneous. The methyl ester yields by two-step transesterification and direct transesterification were 95 and 96% for Scenedesmus sp. and 89 and 92% for Chlorella sp. respectively. Both methods had similar net energy consumption suitable for industrial application. The methyl ester properties were analysed in comparison with those of American Society for Testing and Materials (ASTM) D6751 standards.

Lipids rich in ω-3 polyunsaturated fatty acids from microalgae

Despite microalgae recently receiving enormous attention as a potential source of biodiesel, their use is still not feasible as an alternative to fossil fuels. Recently, interest in microalgae has focused on the production of bioactive compounds such as polyunsaturated fatty acids (PUFA), which provide microalgae a high added value. Several considerations need to be assessed for optimizing PUFA production from microalgae. Firstly, a microalgae species that produces high PUFA concentrations should be selected, such as Nannochloropsis gaditana, Isochrysis galbana, Phaeodactylum tricornutum, and Crypthecodinium cohnii, with marine species gaining more attention than do freshwater species. Closed cultivation processes, e.g., photobioreactors, are the most appropriate since temperature, pH, and nutrients can be controlled. An airlift column with LEDs or optical fibers to distribute photons into the culture media can be used at small scale to produce inoculum, while tubular and flat panels are used at commercial scale. Depending on the microalgae, a temperature range from 15 to 28 °C and a pH from 7 to 8 can be employed. Relevant conditions for PUFA production are medium light irradiances (50-300 μmol photons m(-2) s(-1)), air enriched with (0-1 % (v/v) CO2, as well as nitrogen and phosphorous limitation. For research purposes, the most appropriate medium for PUFA production is Bold's Basal, whereas mixotrophic cultivation using sucrose or glucose as the carbon source has been reported for industrial processes. For cell harvesting, the use of tangential flow membrane filtration or disk stack centrifugation is advisable at commercial scale. Current researches on PUFA extraction have focused on the use of organic solvents assisted with ultrasound or microwaves, supercritical fluids, and electroporation or are enzyme assisted. Commercial-scale extraction involves mainly physical methods such as bead mills and expeller presses. All these factors should be taken into account when choosing a PUFA production system, as discussed in this review.

Advances in techniques for assessment of microalgal lipids

Microalgae are a varied group of organisms with considerable commercial potential as sources of various biochemicals, storage molecules and metabolites such as lipids, sugars, amino acids, pigments and toxins. Algal lipids can be processed to bio-oils and biodiesel. The conventional method to estimate algal lipids is based on extraction using solvents and quantification by gravimetry or chromatography. Such methods are time consuming, use hazardous chemicals and are labor intensive. For rapid screening of prospective algae or for management decisions (e.g. decision on timing of harvest), a rapid, high throughput, reliable, accurate, cost effective and preferably nondestructive analytical technique is desirable. This manuscript reviews the application of fluorescent lipid soluble dyes (Nile Red and BODIPY 505/515), nuclear magnetic resonance (NMR), Raman, Fourier transform infrared (FTIR) and near infrared (NIR) spectroscopy for the assessment of lipids in microalgae.

Experimental study and thermodynamic modeling for determining the effect of non-polar solvent (hexane)/polar solvent (methanol) ratio and moisture content on the lipid extraction efficiency from Chlorella vulgaris

In this research, organic solvent composed of hexane and methanol was used for lipid extraction from dry and wet biomass of Chlorella vulgaris. The results indicated that lipid and fatty acid extraction yield was decreased by increasing the moisture content of biomass. However, the maximum extraction efficiency was attained by applying equivolume mixture of hexane and methanol for both dry and wet biomass. Thermodynamic modeling was employed to estimate the effect of hexane/methanol ratio and moisture content on fatty acid extraction yield. Hansen solubility parameter was used in adjusting the interaction parameters of the model, which led to decrease the number of tuning parameters from 6 to 2. The results indicated that the model can accurately estimate the fatty acid recovery with average absolute deviation percentage (AAD%) of 13.90% and 15.00% for the two cases of using 6 and 2 adjustable parameters, respectively.

Low-Molecular-Weight Metabolites from Diatoms: Structures, Biological Roles and Biosynthesis

Diatoms are abundant and important biological components of the marine environment that biosynthesize diverse natural products. These microalgae are rich in various lipids, carotenoids, sterols and isoprenoids, some of them containing toxins and other metabolites. Several groups of diatom natural products have attracted great interest due to their potential practical application as energy sources (biofuel), valuable food constituents, and prospective materials for nanotechnology. In addition, hydrocarbons, which are used in climate reconstruction, polyamines which participate in biomineralization, new apoptotic agents against tumor cells, attractants and deterrents that regulate the biochemical communications between marine species in seawaters have also been isolated from diatoms. However, chemical studies on these microalgae are complicated by difficulties, connected with obtaining their biomass, and the influence of nutrients and contaminators in their environment as well as by seasonal and climatic factors on the biosynthesis of the corresponding natural products. Overall, the number of chemically studied diatoms is lower than that of other algae, but further studies, particularly those connected with improvements in the isolation and structure elucidation technique as well as the genomics of diatoms, promise both to increase the number of studied species with isolated biologically active natural products and to provide a clearer perception of their biosynthesis.

Supercritical fluid extraction of valuable compounds from microalgal biomass

Many studies have demonstrated that the global demand for renewable biofuels, natural food pigments, and antioxidants has made microalgae a more attractive alternative resource. The application of supercritical fluid extraction (SFE) on the valuable compounds recovery from microalgal biomass has several advantages as compared to the conventional organic solvent extraction methods, especially for environmental considerations. This review presents comprehensive information on the current state of using SFE to recover valuable components from microalgal biomass, such as total lipids, long chain fatty acid and pigments, as well as the utilization and characteristics of the SFE technology. In addition, key factors and challenges that should be addressed during the application of SFE technology are also discussed. This report provides a useful guide that can aid in the future development of more efficient microalgae-based biorefinery process.

Biomass of freshwater Cladophora as a raw material for agriculture and the cosmetic industry

This study was undertaken to determine mineral content, amino acid and fatty acid composition of the freshwater macroalga – Cladophora glomerata. The studies were based on the content comparison in algal biomass collected from a lake and cultured in a laboratory. To determine the ability of copper cumulating by macroalgae, Cladophora was cultured in the medium supplemented with Cu ions. This study indicated that the relative abundance of metals in filaments decreased in the following order: Ca > K > Mg > Na > Fe > Cu > Zn > Pb > As > Ni > Cd > Mn > Cr > Co. Total protein content ranged from 14.45% in Cladophora from a lake to 26.55% in Cladophora from a laboratory. The main amino acids analyzed were aspartic and glutamic acid. The fatty acid content in the dry matter of the extract varied depending on the extraction method used: ethylene alcohol (19.0%), acetone (34.5%) or supercritical fluid extraction (62.5%). Freshwater C. glomerata due to the macrominerals, trace elements, amino and fatty acids composition in the extracts can be a valuable resource for nutritional and cosmetic applications.

Selective esterification to produce microalgal biodiesel and enrich polyunsaturated fatty acid using zeolite as a catalyst

A novel integrated process to produce microalgal biodiesel and simultaneously enrich high-value polyunsaturated fatty acids (PUFA) using selective catalyst.

Lipid profiling and corresponding biodiesel quality of Mortierella isabellina using different drying and extraction methods

Four lipid extraction methods (Bligh & Dyer, hexane & isopropanol, dichloromethane & methanol, and hexane) were evaluated to extract lipid from freeze- and oven-dried fungus Mortierella isabellina ATCC42613. The highest lipid yield (41.8%) was obtained from Bligh & Dyer extraction on the oven-dried fungal biomass with a methanol:chloroform:water ratio of 2:1:0.8. Other lipid extraction methods on both freeze- and oven-dried samples had lipid yields ranging from 20.7% to 35.9%. Non-polar lipid was the main lipid class (more than 90% of total lipid) in M. isabellina. Regarding fatty acid profile, there was no significant difference on fatty acid concentration between different drying and extraction methods. Estimation of biodiesel fuel properties using correlative models further demonstrated that the fungal biodiesel is a good alternative to fossil diesel.

Coupling of algal biofuel production with wastewater

Microalgae have gained enormous consideration from scientific community worldwide emerging as a viable feedstock for a renewable energy source virtually being carbon neutral, high lipid content, and comparatively more advantageous to other sources of biofuels. Although microalgae are seen as a valuable source in majority part of the world for production of biofuels and bioproducts, still they are unable to accomplish sustainable large-scale algal biofuel production. Wastewater has organic and inorganic supplements required for algal growth. The coupling of microalgae with wastewater is an effective way of waste remediation and a cost-effective microalgal biofuel production. In this review article, we will primarily discuss the possibilities and current scenario regarding coupling of microalgal cultivation with biofuel production emphasizing recent progress in this area.