Fatty Acid Methyl Ester Profiles Research Articles

Effect of salt stress on the biomass productivity and potential bioenergy feedstock of Graesiella emersonii KNUA204 isolated from Ulleungdo Island, South Korea

Microalgae are versatile, profitable, and promising sources of bioenergy and high-value products, having various applications in the biotechnology industry. Herein, G. emersonii KNUA204 was isolated from Ulleungdo Island, South Korea, and exposed to stressors, i.e., MgCl2 (75 and 150 mM) and NaCl (200 and 400 mM), to investigate improvement in its biomass productivity and feasibility of the application of biomass. Treatment with mild MgCl2 (75 mM) afforded the highest specific growth rate (μ = 0.13 d−1), dry cell weight (3 g L−1), and total carbohydrate content (29.87%). Although all salt treatments decreased chlorophyll and carotenoid contents, treatment with high NaCl concentration (400 mM) afforded the highest zeaxanthin content (0.3 mg g−1). The proximate and ultimate analyses of biomass following treatment with 150 mM MgCl2 revealed 93.85% volatile matter and 22.55 MJ kg−1 calorific value, respectively, indicating that Graesiella emersonii KNUA204 can be potentially used as bioenergy feedstock. The biodiesel quality was established based on the fatty acid methyl ester profiles, and MgCl2 treatment increased the cetane number more than the control. Therefore, the treatment of G. emersonii KNUA204 with MgCl2 during cultivation could provide a microalgae-based bioenergy feedstock with high productivity.

Identifications of Surfactin-Type Biosurfactants Produced by Bacillus Species Isolated from Rhizosphere of Vegetables.

Surfactins are cyclic lipopeptides consisting of a β-hydroxy fatty acid of variable chain length and a peptide ring of seven amino acids linked together by a lactone bridge, forming the cyclic structure of the peptide chain. These compounds are produced mainly by Bacillus species and are well regarded for their antibacterial, antifungal, and antiviral activities. For their surfactin production profiling, several Bacillus strains isolated from vegetable rhizospheres were identified by their fatty acid methyl ester profiles and were tested against phytopathogen bacteria and fungi. The isolates showed significant inhibition against of E. amylovora, X. campestris, B. cinerea, and F. culmorum and caused moderate effects on P. syringae, E. carotovora, A. tumefaciens, F. graminearum, F. solani, and C. gloeosporioides. Then, an HPLC-HESI-MS/MS method was applied to simultaneously carry out the quantitative and in-depth qualitative characterisations on the extracted ferment broths. More than half of the examined Bacillus strains produced surfactin, and the MS/MS spectra analyses of their sodiated precursor ions revealed a total of 29 surfactin variants and homologues, some of them with an extremely large number of peaks with different retention times, suggesting a large number of variations in the branching of their fatty acid chains.

Phycoremediation of cashew nut processing wastewater and production of biodiesel using Planktochlorella nurekis and Chlamydomonas reinhardtii

The present study examined the biomass enrichment of two microalgal strains, Planktochlorella nurekis and Chlamydomonas reinhardtii in cashew nut processing wastewater (CNPW) along with the simultaneous production of biofuel as well as wastewater treatment. The strains were initially grown in Bold's Basal Medium (BBM) before being introduced into CNPW under experimental conditions. The physico-chemical parameters, heavy metal concentration and biomass content were analyzed periodically. The produced biomass was used for the production of biodiesel and the Fatty acid methyl esters (FAME) of the biodiesel were estimated along with its quality. The results of the study revealed a significant improvement in the quality of CNPW within 13 days. P. nurekis (1.914 ± 0.02 g/L) showed higher biomass production than C. reinhardtii (1.503 ± 0.069 g/L). The physico-chemical analysis showed that P. nurekis and C. reinhardtii could significantly reduce nitrate, phosphate and COD from CNPW. The percentage reduction of heavy metals such as Cd, Cr, Ni, Cu and As were 93.2 %, 99.7 %, 98.7 %, 99 % and 90.6 %, respectively when treated with P. nurekis. Similarly, the percentage reduction of the aforesaid heavy metals by C. reinhardtii were 75.7 %, 65.9 %, 72.5 %, 78.5 % and 87.4 % respectively. The FTIR analysis revealed the presence of the functional groups such as amines, alkenes, carboxylic acid, phenol, nitro compound, amide and alcohols in both strains. The FAME profile of both strains showed a moderate concentration of C16–C18 fatty acids content. The quality analysis of biodiesel produced by both species revealed that all the physical properties were within the permissible limits as per ASTM D6751–02 and EN 14214. Comparatively, P.nurekis exhibited notable phycoremediation capacity as well as lipid production potential than C. reinhardtii. The present study has shown that both species are the promising candidates for wastewater treatment.

Fatty acids methyl esters from soybean oil for biobased surfactants industry: Obtention C16 / C18 concentrate for use as feedstock

Soybean fatty acid methyl esters (FAMEs) are used as biodiesel, a co-fuel according to current consumption figures. In addition, FAMEs are becoming increasingly important as biodegradable substitutes for mineral oils, such as oil for chainsaws, gearboxes, hydraulics, and lubricants for crude oil production. Therefore, the possibility of producing a wide spectrum of value-added products in oleochemical industry will guarantee the competitiveness of biodiesel plants in the market. In this way, soybean FAMEs of local production were modified to obtain the desired characteristics to produce biobased surfactants as methyl ester sulfonated (MES). In order to incorporate soybean FAMEs into the conventional MES manufacturing process, their lipid profile must be similar to that of the traditionally used raw material, that is, palm oil. This oil is composed of acids with a length between C12 and C18 and 44–50 % of unsaturated acids, a higher concentration of unsaturated acids is not convenient because generated impurities could affect the final color of the product. Thus, the objective of this work is to achieve a ratio between soybean C16/C18 FAMEs of 60/40, the maximum possible ratio from the initial C16/C18 of 11.0/87.6. In this study, molecular distillation and urea complexation were used as individual and combined techniques to obtain C16/C18 concentrate. In the molecular distillation a ratio of 16.2 / 83.1 was obtained with a yield of 23.2 % (evaporation temperature of 70 °C) while by urea complexation a ratio of 35.4/ 60.8 was obtained with a yield of 32.0 % (urea: FAMEs mass ratio of 1: 1). The most suitable combination of both techniques was a urea complexation stage followed by a molecular distillation stage. The obtained product had a ratio of 56.7 / 43.3 and a yield of 41.8 %. The results of this study could be applied to other vegetable sources to obtain an appropriate profile of FAMEs. Also, the developed process in this work could be used in the industry of green surfactants to produce the segmentation of biodiesel industry. • FAMEs from soybean oil could be used in the biobased surfactants industry. • Urea Complexation and Molecular Distillation combined could join to biodiesel industry. • This method of purification allows a greater productive diversification of biodiesel. • The combination of two techniques allows modifying the FAMEs profile of soybean oil.

Maximizing Nitrogen Removal and Lipid Production by Microalgae under Mixotrophic Growth Using Response Surface Methodology: Towards Enhanced Biodiesel Production

The present study aimed to optimize synthetic wastewater composition as a mixotrophic medium for enhanced growth and lipid accumulation coupled with high nitrogen removal by the green microalga Chlorella sp. Individual effects of the three main independent variables (nitrate concentration, seawater ratio, and glycerol supplementation) were tested initially, then response surface methodology (RSM) was subsequently performed to explore the optimum combined conditions. The highest lipid productivity of 37.60 mg/L day was recorded at 25% seawater. Glycerol supplementation enhanced both lipid content and biomass production, which resulted in the highest recorded lipid productivity of 42.61 mg/L day at 4 g/L glycerol. Central composite design followed by numerical optimization was further applied which suggested NaNO3 concentration at 101.5 mg/L, seawater ration of 23.8%, and glycerol supplementation of 0.25 g/L as the optimum conditions for dual maximum lipid productivity and nitrogen removal of 46.9 mg/L day and 98.0%, respectively. Under the optimized conditions, dry weight and lipid content increased by 31.9% and 20.3%, respectively, over the control, which resulted in increase in lipid productivity by 71.5%. In addition, optimization process resulted in pronounced changes in fatty acid proportions where saturated fatty acids increased by 7.4% in the optimized culture with simultaneous reduction of polyunsaturated fatty acids. The estimated biodiesel characteristics calculated from the fatty acid methyl ester (FAMEs) profile showed agreement with the international standards, while optimized cultures showed an 8.5% lower degree of unsaturation, which resulted in higher cetane numbers and lower iodine values. This study provides economical approach for optimization and efficient nutrient recycling through cultivation of Chlorella sp. for further enhanced biodiesel production.

Study on the Potential for Biodiesel Production of Microalgal Consortia from Brackish Water Environment in Rayong Province, Thailand

Microalgae are photoautotrophic microorganisms that can be grown in a wide variety of water environments. They are the most promising biodiesel source, with the potential to replace fossil diesel. In this study, microalgae samples were collected from the brackish water environment of three locations in Rayong province, Thailand including Phra Chedi Klang Nam (PKC), Noen Kho Canal (NKC), and Raksamae Bridge (RSM), and induced to form multi-algae communities or microalgal consortia (MC). All consortia were cultured and analyzed for their ability to produce biomass and lipid. The result was found that the biomass concentration of MC-RSM was 0.65 ± 0.05 mg.L-1, which is higher than 1.2 and 1.5-times of MC-PCK and MC-NKC, respectively. The most common microalgae species found under all cultures were green algae (Chlorophyta) and diatom (Bacillariophyta), and the dominant species was the green algae, Chlorella sp. The lipid content of all samples ranged from 28.07 ± 0.60 to 33.21 ± 0.79% of dry weight, and the highest value was noticed in the MC-RSM sample. The fatty acid composition of fatty acid methyl ester (FAME) was also evaluated as feasibility for biodiesel production. FAME profiles of each sample showed high amounts of saturated fatty acids (SFAs) ranging from 67.82%-71.31% of total fatty acids. The majority of the SFAs in all were palmitic acid (C16:0) followed by myristic acid (C14:0, and stearic acid (C18:0). Therefore, all microalgal consortia showed great fatty acid profiles and these have the potential for use as feedstock for biodiesel production.

Green synthesis of magnesium oxide nanosheets by using Citrullus colocynthis fruit extract and its use in biofuel production

The present study focuses on the novel green synthesis approach of heterogeneous MgO nanocatalyst for biodiesel production from a novel Citrullus colocynthis fruit extract while the tea plant (Camellia assamica) is used as a source for oil. The green synthesis method is an environmentally friendly, cost-effective, non-toxic, and easy method yielding high biodiesel synthesis efficiency as compared to a homogenous catalyst. The XRD results confirm the required MgO phase with an average crystallite size of 42.6 nm. A sheet-like porous morphology of MgO in the range of 1–5 nm is observed from FESEM/EDX analysis with a surface area of 147.4 m2 g−1 and mesopores laying in the range of 20–30 nm as calculated from the BET and BJH analysis, respectively. This novel nanocatalyst showed high conversion efficiency of the green tea seed oil into fatty acid methyl ester (Biodiesel). The GC-MS and FTIR are used to confirm the conversion of tea seed oil into biodiesel. The maximum biodiesel yield of ∼100% was obtained at a temperature of 60 °C, a methanol/oil molar ratio of 6:2, a catalyst content of 6.25 wt%, and a reaction time of 1.5 h. The fuel properties of the produced biodiesel are well within the range of international standards and the fatty acid methyl ester profile confirms its viability and reliability as an alternative fuel source for an internal combustion engine.

A high throughput method for fatty acid profiling using simultaneous microwave-assisted extraction and derivatization followed by reversed fill/flush flow modulation comprehensive multidimensional gas chromatography

The fatty acid composition of a food product provides information regarding the origin of the product and its overall quality, such as its nutritional value. This work proposes a fast and accurate method for preparing fatty acid methyl esters from a wide variety of food products by using a single-step microwave-assisted extraction and derivatization coupled to reversed fill/flush flow modulation comprehensive two-dimensional gas chromatography (GC×GC) – flame ionization detector (FID) to tentatively identify and quantify the individual fatty acid. The robustness of the GC×GC – FID platform was successfully assessed, as well as the reliability of the entire proposed procedure, assuring repeatability largely below 10%. The enhanced separation obtained by the use of GC×GC allowed for the identification of 81 FAMEs in a single run of 30 min. The fatty acid methyl esters profiles obtained with the proposed microwave-assisted extraction and derivatization were comparable with reference methods from the literature and the American Oil Chemistry Society. This method also proved to be a significant step towards a greener procedure than the reference one when evaluated based on the PrepAGREE metrics that have been recently proposed.

Impact of edaphoclimatic conditions and crop season on olive oil's fatty acids

AbstractThe olive tree (Olea europaea L.) fruit oil attracts widespread interest because of its high content of monounsaturated fatty acids. However, a neglected area in the field is the edaphoclimatic factors impact, which is poorly understood. Bearing this in mind, the purpose of this investigation was to evaluate the impact of the edaphoclimatic conditions on the fatty acids’ composition. Therefore, we have investigated the fatty acids methyl ester (FAME) profile in 38 monovarietal Moroccan ‘Picholine Marocaine’ extra‐virgin olive oils (EVOOs) from two successive crop years (2018–2019 and 2019–2020). Significant differences were detected in olive oils from distinct geographical origins with about 10 and 4% of the difference in oleic and palmitic acid amounts in both seasons; however, linoleic acid showed 5 and 8% in 2018–2019 and 2019–2020 oils, respectively. Furthermore, regions of high altitude and low temperature resulted in olive oils rich in oleic acid and monounsaturated fatty acids (MUFAs). This study also revealed the negative impact of rainfall, sand percentage, and nitrogen on saturated fatty acids (SFAs) and of pH and conductivity on the major MUFAs.

Enhancing growth environment for attached microalgae to populate onto spent coffee grounds in producing biodiesel

One of the economical approaches to harvest mature microalgal biomass is through the attached growth system, in which the microalgal cells form attachment onto support material to facilitate its separation from the cultivation medium. Hence, the spent coffee grounds (SCG) was employed as the support material, proffering alimentation, and platform for Chlorella vulgaris sp. microalgae, to populate its surface. The SCG dosage of 8 g L−1 was revealed as optimum in enhancing the attached microalgal growth, i.e., achieving the microalgae density of 2.43 ± 0.04 g g-SCG−1 under continuous illumination. The introduction of a 20:4 photoperiod regime with the dark period cycle of 4 h day−1 and the remaining 20 h day−1 of illumination yielded a maximum microalgal density of 3.970 ± 0.8 g g-SCG−1. In this regard, the dark period had allowed the attached microalgae to strengthen their mixotrophic growth, i.e., assimilating more carbon from SCG effectively amidst heterotrophic mode. Besides, the extension of the dark period to 20 h day−1 had been identified as the threshold requirement to stress the attached microalgae in accumulating a significant amount of lipid which was about fivefold more productive than the attached microalgae growing under the continuous illumination. The fatty acid methyl esters (FAME) profile derived from harvested attached microalgal biomass was loaded primarily with alkyl chains of C12 to C18. Also, the high saturation degree of FAME had indicated the stability of biodiesel produced from attached microalgae growing onto SCG feedstock.

Electrostatic field and nano-adsorbent refining of fatty acid methyl esters

Conventional crude fatty acid methyl ester (FAME) refining requires the use of expensive infrastructure, demands large water inputs, generates substantial amounts of waste, and is associated with substantial amounts of loss of FAME. In this study, electrostatic field (E-field) and nano-adsorbents were employed as novel tools in refining crude FAME. A reduction (37.6%) in soap content was immediately observed after treatment via E-field; however, total glyceride content remained unchanged. Soap content in crude FAME was further significantly reduced through the addition (<4 wt %) of nano-adsorbents (Al2O3, SiO2, and TiO2) in 6 min, with minimal agitation (≤600 rpm), and at ambient temperature. After adsorption, the spent Al2O3, SiO2, and TiO2 nano-adsorbents were successfully removed from FAME via E-field treatment, as observed by a reduction of 79.3 wt %, 75.4 wt % and 19.0 wt %, respectively. In addition, minimal FAME loss (0.66 wt %) was observed when using E-field treatment. Similarly, nano-adsorbent treatments were reported causing FAME loss of 0.45 wt %, 2.7 wt %, and 2.1 wt % for Al2O3, SiO2, and TiO2 nano-adsorbents, respectively. Furthermore, none of these treatments affected the FAME profile and, therefore, it is likely that exposure to the E-field did not affect FAME chemistry. The Al2O3 nano-adsorbent was successfully washed and reused for refining FAME. Altogether, crude FAME refining utilizing both E-field and nano-adsorbents treatment technologies offers distinct advantages as alternatives to conventional FAME refining methods.

The effect of biodiesel production method on its combustion behavior in an agricultural tractor engine.

In this study, biodiesel fuel was produced from waste cooking oil (WCO) using a heterogeneous catalyst under microwave (MB) and conventional (CB) heating, and fueled in an agricultural tractor engine to evaluate the engine performance as well as emissions. The biodiesels presented different fatty acid methyl ester (FAME) profiles where MB had lower unsaturated FAME chains. Beyond the transesterification reaction time, the energy consumed for MB biodiesel production diminished by around eight times compared to that required for CB production. The engine results confirmed the positive influence of blending net diesel fuel with biodiesel for enhancing the engine performance and reducing the emissions. More than 20% increment in the engine power and torque was detected at all engine loads (the engine speed was adjusted at 1500rpm). The hydrocarbon (HC), carbon monoxide (CO), and smoke opacity (SO) indicated significant reductions compared to when net diesel fuel was used. According to statistical analysis, CB25 and MB25 fuels presented a suitable combination as fuel where MB25 provided better engine performance, lower HC and SO emissions, with CO emissions reaching the minimum amount by CB fuels.

Integrating eco-technological approach for textile dye effluent treatment and carbon dioxide capturing from unicellular microalga Chlorella vulgaris RDS03: a synergistic method

A pilot-scale treatment method was used in the present study to test the biosorption of textile dye from textile effluent and carbon dioxide using Chlorella vulgaris RDS03. The textile dye effluent treatment achieved that textile dye biosorption capacity (qmax) rate of 98.84% on 15 days of treatment using Chlorella vulgaris RDS03. The Langmuir and Freundlich isotherm kinetics model indicated that the higher R2 value 0.98. The microalga Chlorella vulgaris RDS03 was captured-96.86% of CO2 analyzed by CO2 utilization and biofixation kinetics, 4.65 mgmL−1 of biomass, 189.26 mgg−1 of carbohydrate, 233.89 mgg−1 of lipid, 4.3 mLg−1 of bioethanol and 4.9 mLg−1 of biodiesel produced. We performed fatty acid methyl ester (FAME) profiling using gas chromatography-mass spectrometry (GCMS). We found 40 types of biodiesel compounds, specifically myristic acid, pentadecanoic acid, octadecanoic acid, palmitic acid, and oleic acid. The high-performance liquid chromatography (HPLC) validated and analyzed the produced bioethanol. Novelty of the Research • Unicellular microalga Chlorella vulgaris RDS03 was isolated from the freshwater region and investigated their biosorption efficiency against hazardous synthetic azo textile dyes. • Chlorella vulgaris RDS03 ability to biosorption 96.86% of environmental polluted carbon dioxide • Treated biomass was used to produce ecofriendly, unpolluted and green energy such as biofuels (biodiesel and bioethanol)

Cold stress stimulates algae to produce value-added compounds

Two cold-tolerant microalgae, Chlorella vulgaris and Scenedesmus sp., were grown at 22 and 5 °C. At the lower temperature, the microalgae showed substantial biochemical and morphological changes. The soluble sugar profile in response to low-temperature cultivation was very different in the two strains. C. vulgaris increased both the sucrose and raffinose family oligosaccharides (RFOs) content at 5 °C while Scenedesmus sp. drastically reduced the sucrose content. Both strains increased the total fatty acid methyl ester (FAME) content when grown at 5 °C. However, the FAME profiles were very different: C. vulgaris mainly increased C18:1 and less so C18:3, while Scenedesmus sp. decreased C18:1 but greatly increased C18:3. The morphology of C. vulgaris changed slightly at the lower temperature, while Scenedesmus sp. showed substantial changes in the size and shape. Low temperature triggered the synthesis of unsaturated fatty acids that are essential for human nutrition.

ISOLATION, CHARACTERIZATION AND IDENTIFICATION OF AN As(V)-RESISTANT PLANT GROWTH PROMOTING RHIZOBACTERIUM ASSOCIATED WITH THE RHIZOSPHERE OF Azolla microphylla

In the present study, bacterial strains were obtained from the rhizosphere of Azolla microphylla Kaulf. and their arsenic (As) tolerance was tested under in-vitro conditions. Out of the two bacteria screened for As(V) tolerance, strain R1 was found to have the highest As(V) tolerance level at 2000 mg/l and was found to retain up to 58.76% of As given in the medium solution within its cells, as revealed by inductively coupled plasma optical emission spectroscopy analysis. This efficient As(V)-resistant strain was identified using16S rRNA sequencing and fatty acid methyl ester profile analysis, and was found to be a strain of Bacillus cereus (GenBank accession number MH819519). Along with showing abundance of hallmark fatty acids of the Bacillus cereus group, some unique fatty acids were also detected in the bacterial strain R1, namely 15:1 ω5C, 17:1 iso ω10C, 17:1 ante isoA, 17:0, 18:0 iso, 18:1 ω9c, and 17:1 iso ω5C. At its maximum tolerable As(V) dose of 2000 mg/l, strain R1 showed 59.9% As(V) reduction, which was assessed through arsenate reductase enzyme activity. Not only this, under As(V) stress, strain R1 was found to produce 20.4% more cellular protein and display 30.3% antioxidant activity assayed as DPPH reduction. The bacterium is also capable of exhibiting plant growth promoting traits such as solubilisation of inorganic phosphate, production of siderophore and biosynthesis of the plant growth regulator indole acetic acid. Thus, this bacterium has the potential to remediate As(V) from environment and also assist the growth of plants growing in As-polluted ecosystems.

NITROGEN STARVATION INDUCED LIPID ACCUMULATION BY Chlorococcum infusionum (EAU-10) AS POTENTIAL RENEWABLE SOURCE OF LIPID FOR BIODIESEL PRODUCTION

Microalgae are organisms effective of accumulating high quantity of industrially important lipids with promising characteristics as an excellent feedstock for biodiesel production. This study assess the possibility of using a green microalga, Chlorococcum infusionum (EAU-10) for biodiesel production by evaluating the growth characteristic, lipid yield and fatty acid profile of the microalga cultivated at varying concentrations of nitrogen source (0.375 - 1.50 g L-1 NaNO3). High lipid accumulation was observed in nitrogen-starved cultivation condition (0.375 g L-1 NaNO3) after 23 days of growth. Maximum biomass concentration of Chlorococcum infusionum (EAU-10) under nitrogen starved condition is 0.577 ± 0.003 g L−1 with 21.26% oil content per dry weight of algal biomass and lipid productivity of 22.08 mg L−1 day−1. Nitrogen starvation caused an increase in the total oil content and a decrease in biomass production of the microalga. Profiling of fatty acids of the obtained algal biodiesel shows methyl palmitate (C16:0) and methyl nonadecanoate (C19:0) contribute to almost 70% of Chlorococcum infusionum (EAU-10) fatty acid methyl esters (FAME) profile. Overall, a total of 74.58% of saturated fatty acid (SAFA) methyl ester content is present in the algal lipid, which is exceedingly high in contrast to other similar studies. Analysis of C. infusionum FAME profile in relation to some important fuel properties showed that the algal oil has the potential to produce biodiesel with excellent fuel qualities.

Bioenergy characteristics of microalgae under elevated carbon dioxide

Nowadays, biological mitigation of carbon dioxide (CO2) by means of microalgae is one of the promising approaches, as biomass can be used to produce renewable fuels such as biodiesel and crude bio-oil. In this study, the growth ofDesmodesmussp. in response to different CO2levels (ambient air, 5%, 10%, 15%, 20%, 25%, 30%, and 35% CO2) was studied, and then the suitability of the biomass for bio-oil and biodiesel production was evaluated. The studied strain was able to grow efficiently in a broad range of elevated CO2(5–30%,v/v), suggesting its suitability for CO2mitigation. The highest specific growth rate (0.769 d−1) and biomass productivity (0.033 g L−1d−1) were achieved at 15% CO2; therefore, the concentration of 15% CO2was selected as the optimum. Alpha-Linolenic acid (ALA) was the dominant polyunsaturated fatty acids (PUFAs) in studiedDesmodesmusstrain, and its content increased from 31.82% under ambient air to 41.94% and 50.11% under 15% CO and 30% CO2, respectively, suggesting a key role of ALA in response to CO2elevation. Using fatty acid methyl ester (FAME) profiles of cultures in different CO2conditions, biodiesel parameters such as cetane number (CN), saponification value (SV), iodine value (IV), long chain saturation factor (LCSF), oxidative stability (OS), higher heating value (HHV) and degree of unsaturation (DU) were estimated. Overall, the lipid extract was not suitable for biodiesel production due to high PUFA content ranging between 52.91% and 71.14%. Under optimum CO2(15%), saturated fatty acids (SFAs) content increased to 31.91% and PUFA content reduced to 52.91%. This could significantly improve the CN to 38.07, which was 11% and 13% higher than theair and 30% CO2. Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) was used to analyze the potential of microalgal biomass for bio-oil production upon CO2changes. The pyrolysate contained 40–47% acid content due to the high content of fatty acids. The pyrolysate quality declined under 15% CO2due to the higher accumulation of acidic and nitrogen-containing compounds and reduced hydrocarbon proportion.In conclusion, the optimum CO2could enhance biodiesel parameters such as CN, but demonstrated negative effects on bio-oil quality.

Biodiesel (fatty acid methyl ester) from Chlorococcalean Chlorella vulgaris by single step in-situ transesterification

Objectives: To study the single step in-situ transesterification process for synthesis of fatty acid methyl ester (biodiesel) from microalgae biomass Chlorococcalean Chlorella vulgaris. Methods: The growth and lipid productivity of an isolated microalgae C. vulgaris were studied under Chu‘s 10 modified media under phototrophic cultivation conditions. In-situ transesterification of this dry biomass with methanol in presence of base catalyst at 60 º C was carried out to investigate the fatty acid methyl ester’s biochemical composition by FTIR & analysis performed using GCMS technique. The cetane number was also calculated. Findings: The biodiesel fraction from C. vulgaris biomass was found to be 85.58%. The 43.40% lipid fraction was obtained from the biomass of C. vulgaris. In the in-situ transesterification process, the optimal concentration of potassium hydroxide (KOH) and methanol yields an 85.58 percent biodiesel fraction. The presence of lipid compounds and the biochemical composition of fatty acid methyl ester were verified with the help of FTIR spectral analysis. The gas chromatography-mass spectrometry analysis explores the fatty acid methyl ester profile, which comprises 29.05% and 56.54 percent saturated and unsaturated FAMEs. Through GCMS, the fatty acid methyl ester composition of C. vulgaris microalgae species was revealed through six types of fatty acid methyl esters, of which 54.95%, 11-octadecenoic acid methyl ester, is the dominant one. The cetane number of C. vulgaris biodiesel was determined to be 67.726; this is comparable to diesel fuel according to ASTM-D613, and the presence of a higher fatty acid methyl ester composition indicates favourable biofuel qualities. Novelty: The calculation of cetane number by theoretical method and affirmation of ecofriendly single step in-situ transesterification method for biodiesel production. Keywords: Chlorococcalean Chlorella vulgaris; Biodiesel; GCMS; FTIR; Cetane Number

Modeling the effects of biodiesel chemical composition on iodine value using novel machine learning algorithm

Biodiesel is a promising renewable energy the use of which facilitates the goals of carbon neutrality and timely carbon peak. The iodine value (IV), one of the major properties of biodiesel, denotes the degree of unsaturation and correlates with the chemical composition of biodiesel. In this work, a novel approach based on random forest (RF) and least squares support vector machine (LSSVM) algorithms optimized by whale optimization algorithm (WOA) is proposed for estimating the IV of biodiesel as a function of fatty acid methyl ester profiles. In doing so, the compositions and IVs of 52 biodiesel/binary biodiesel blends were determined by gas chromatography mass spectrometry and EN14111 standard. Then, LSSVM algorithm was assessed as the most appropriate predictive method compared to the adaptive neuro fuzzy inference system, multi-layer perceptron neural network, and decision tree algorithms. Continuously, four feature selection approaches (Pearson’s correlation coefficient, principal component analysis, ReliefF algorithm, and RF) were utilized to choose the most influencing fatty acid methyl ester combination as input. The RF-LSSVM model was found to be superior to other Ⅰ hybrid models. Then, WOA was incorporated into the modeling process and the RF-WOA-LSSVM model achieved a high performance with a root mean square error and correlation coefficient of 1.1893 and 0.9977, respectively. The accuracy and error of the RF-WOA-LSSVM model have been validated. Comparison with previous biodiesel IV machine learning models and application of other new experimental datasets from the literature prove the feasibility of the proposed hybrid RF-WOA-LSSVM model for estimating the IV of different biodiesels types.

Directed evolution of Chlorella sp. HS2 towards enhanced lipid accumulation by ethyl methanesulfonate mutagenesis in conjunction with fluorescence-activated cell sorting based screening

The present study aimed to improve the lipid content and lipid productivity of Chlorella sp. HS2 by exposing them to ethyl methanesulfonate (EMS) to generate a mutant and followed with fluorescent assorted cell sorting (FACS) for the selection of mutant cells having desirable phenotypes. The microalgae were subjected under 100 μ mol mL−1 concentration of EMS for 30 min, followed by intracellular lipid staining with boron-dipyrromethene (BODIPY) fluorophore for FACS based selection. The biomass growth, lipid content, lipid productivity, and fatty acid composition of the selected mutagenized strain (SMS, TE+F) of Chlorella sp. HS2 were compared against those of FACS selected strain without mutagenesis (FSS, TF) and parent wild strain (PWS, TC), under two different carbon supplementation schemes (only CO2 supply and optimized carbon supply). The highest lipid content and productivity of 35.6% and 248.7 mg L-1 d-1, respectively were observed in the SMS grown under optimized carbon supplementation (1% CO2 (v/v) and 0.5 g L-1 NaHCO3), which was a substantial improvement over those of FSS (26.6% and 193.4 mg L-1 d-1) and PWS (24.7% and 153.6 mg L-1 d-1). The fatty acid methyl ester (FAME) profile of the lipids derived from SMS showed a marked increase in the proportion of saturated fatty acids (SFA) and mono-unsaturated fatty acids (MUFA) (76.7%) over those of FSS (70.2%) and PWS (69.6%). Lastly, fuel properties were found to be appropriate for biodiesel production, as they corroborate with international fuel standards. These results indicate that directed evolution using EMS mutagenesis with FACS is a powerful tool to achieve microalgal strain improvement for biofuel production.