Saturated FAME Research Articles

A cell line derived from the black soldier fly, Hermetia illucens (Diptera:Stratiomyidae).

Insect cell lines are effective tools used in industry and academia. For example, they are used in screening potential insecticides, in making certain proteins for biomedical applications, and in basic research into insect biology. So far, there are no cell lines derived from the black soldier fly, Hermetia illucens (BSF). This may become an issue because BSFs are employed in a range of industrial and household processes. BSFs are used in producing biodiesel, in developing cosmetics and skin creams, and in the production of some medicines and animal feeds. BSF larvae process waste streams from a variety of sources into food for some animals and are also used in household composting. Our BSF cell line, designated BCIRL-HiE0122021-SGS, was developed from eggs using the medium CLG#2 (50% L-15 + 50% EX-CELL 420, with 9% FBS and antibiotics), with many other media being tested. This cell line consists of attached cells with a variety of morphologies and its identity was authenticated using CO1 barcoding. A growth curve was generated and the resulting doubling time was 118 h. We quantified the fatty acid methyl esters (FAMES) and recorded the expected range of saturated, monounsaturated, and polyunsaturated FAMEs, with only trace levels of lauric acid being noted. The BSF cell line is available free of charge by request.

DINAMIKA DAN NYALA API PEMBAKARAN DROPLET CAMPURAN METIL LAURAT – METIL OLEAT

This research intended to investigate the dynamics and flame of the droplet combustion of methyl laurate - methyl oleate blended. Methyl oleate is an unsaturated FAME with a relatively long carbon chain, frequently found as the dominant component in various biodiesel. Meanwhile, methyl laurate is a saturated FAME with a shorter carbon chain, which is the main component in coconut oil biodiesel. The methyl oleate content in the droplets was varied by 0, 20, 40, 60, 80, and 100%. Visual observations and temperature measurements were conducted on the combustion of suspended droplets with a diameter of 1.24 mm. The droplet is supported by a thermocouple junction with a wire diameter of 0.1 mm. The experimental results show that increasing of the methyl oleate content increase the ignition delay time, burning time, thermal expansion of droplets as well as fluctuations in droplet diameter and combustion temperature. Ignition delay time has a much greater value than burning time. This parameter should be suppressed to obtain more complete combustion and cleaner exhaust emissions, especially in internal compression engine applications where the time available for the combustion process is very short. This can be obtained by increasing the percentage of methyl laurate in biodiesel.

Advancing biodiesel production from Pyrus glabra seed oil: Kinetic study and RSM optimization via microwave-assisted transesterification with biocompatible hydroxyapatite catalyst

In this study, a biocompatible hydroxyapatite (HAp) catalyst was synthesized using the chemical precipitation method to create biodiesel (FAME). The HAp was characterized for its structure (FT-IR and XRD), particle size, morphology (SEM and TEM), and surface area (BET). The obtained results indicated that HAp had a spherical shape ranging in size from 28.36 to 51.40 nm, a specific surface area of 21.90 m2/g, and a pore diameter of 15.36 nm. The aforementioned catalyst was employed in the transesterification of Pyrus glabra seed oil, with the assistance of microwaves, and the optimization of the biodiesel production process was achieved using RSM-CCD. The impact of the reaction parameters, including catalyst weight (0.5–1.5 wt%), temperature (60–80 °C), and time (10–30 min), was analyzed. The highest biodiesel yield of 89.21% was achieved in 30 min using a 0.5 wt% catalyst at 80 °C. Microwave-produced FAME was evaluated with FT-IR and GC-MS analysis. GC-MS results revealed 78.02% unsaturated and 13.16% saturated FAME content. The FTIR spectrum validated the presence of methyl and ester groups in the produced biodiesel. Both the FTIR and GC-MS results illustrated that the produced biodiesel had good quality. Transesterification of Pyrus glabra seed Oil followed first-order kinetics with an activation energy of 23.20 kJ/mol and an Arrhenius constant of 2.43 × 104 min−1. The catalyst remained active over six recycling cycles without notable decline. The optimal properties of Pyrus glabra biodiesel, meeting ASTM standards, highlight its potential as a catalyst for large-scale production, aligning with the Sustainable Development Goals (SDGs).

Enzymatic biodiesel synthesis from Trichosporon shinodae yeast through circular economy: A greener approach

In the present study, crude glycerol, a by-product of biodiesel production, was supplemented to Trichosporon shinodae for higher lipid synthesis and further extracted (lipid) using ultrasonic-assisted extraction (UAE). Optimization of enzymatic transesterification (ET) using Response Surface Methodology (RSM) coupled with Central Composite Design (CCD) quadratic model of single-cell oil resulted in 90.03%(v/v) of maximum FAME's yield with methanol to oil ratio of 14.98, solvent to oil ratio of 0.270 in 12.52 h at 25.99 °C with 1.26%(v/v) initial water content. The developed model was significant, with an R2 value of 95.20% and an adj.R2 value of 91.97%. The developed RSM model was further utilized for optimization through the Modified Chaotic Invasive Weed Optimization (MC-IWO). The optimization results showed a maximum FAME's yield of 90.03% utilizing the MC-IWO parameters of 5 seeds with a 6% initial standard deviation using an exponent value of 2 with a population size of 15 in 56 generations. FAME's characterization of T. shinodae has revealed 58.8% (v/v) of saturated FAME's and 41.2% (v/v) of FAME's predominantly with oleic acid methyl ester content (38%,v/v). Fuel properties of T. shinodae showed kinematic viscosity of 3.9–4.4 mm2/s, iodine value (113–115 g I2/100 g), cetane index (46–48), saponification value (203–206 mg/KOH), acid value (1.2–1.4 mg KOH/g) and higher heating value (39–40 MJ/kg). Blending experiments of T. shinodae biodiesel with conventional petroleum showed calorific values of B5, B20 and B100 were 48.63 MJ/kg, 43.45 MJ/kg and 38.35 MJ/kg, respectively. This study showed the potential of T. shinodae biodiesel, which can be used either as an additive or as a blend of conventional fuels.

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

Fuel properties of low-erucic acid pennycress (LEAP) oil biodiesel

Biodiesel is a renewable biobased fuel obtained from transesterification of plant seed oil with methanol. This fuel has physical properties that make it attractive as an alternative fuel for compression-ignition (diesel) engines. In the United States (US), there is a need to increase the production of sustainable and environmentally friendly biofuels, including biodiesel, to supplement fossil fuels. To meet these challenges, emphasis is being placed on expanding the use of low-cost non-food oils as feedstocks for biodiesel. Low-erucic acid pennycress (LEAP) was developed from field pennycress as a cover crop for use in the Upper Midwestern US. The objective of the present study was to convert LEAP oil to biodiesel (fatty acid methyl esters [FAME]) and evaluate its fuel properties. The same process was applied to FAME made from natural field pennycress (FPC) oil as a baseline for comparison of results. The LEAP oil-FAME (LEAP-ME) had a kinematic viscosity at 40 °C (KV40) that was lower than that of FPC oil-FAME (FPC-ME), and nearly equivalent to the KV40 of soybean oil-FAME (SME). The total saturated-FAME (SFAME) concentration of LEAP-ME (5.40 mass%) was greater than that of FPC-ME. Since SFAME have high melting points, this caused LEAP-ME to have a higher cloud point (CP) than FPC-ME. However, the CP of LEAP-ME (−6.8 °C) was lower than those of canola oil-FAME (CaME; −2.5 °C) and SME (−2.8 °C). The oxidative induction period at 110 °C (IP110) of LEAP-ME was poor (0.83 h), indicating that it would need to be treated with antioxidants before distribution as an alternative diesel fuel.

Production of Biodiesel from Spirogyra elongata, a Common Freshwater Green Algae with High Oil Content

The need for exploring nonfood low-cost sustainable sources for biodiesel production is ever increasing. Commercial and industrial algae cultivation has numerous uses in biodiesel production. This study explores S. elongata as a new algal feedstock for the production of biodiesel that does not compete with food production. The major fatty acids identified in S. elongata oil were oleic (30.5%), lauric (29.9%), myristic (17.0%), and palmitic (14.2%) acids. Transesterification to FAME was conducted using basic (KOH), acidic (HCl), and Zeolitic catalysts for assessment. The yields with acidic (54.6%) and zeolitic (72.7%) catalysts were unremarkable during initial screening. The highest biodiesel yield (99.9%) was achieved using KOH, which was obtained with the optimum reaction conditions of 1.0% catalyst, 60 °C, 4 h, and an oil-to-methanol volume ratio of 1:4. The resulting S. elongata oil methyl esters exhibited densities, CNs, and IVs, that were within the ranges specified in the American (ASTM D6751) and European (EN 14214) biodiesel standards, where applicable. In addition, the high SVs and the moderately high CPs and PPs were attributed to the presence of large quantities of short-chain and saturated FAME, respectively. Overall, the composition and properties of FAME prepared from S. elongaae oil indicate that S. elongata is suitable as an alternative algal feedstock for the production of biodiesel.

Optimization of sorbitan monooleate and γ-Al2O3 nanoparticles as cold-flow improver in B30 biodiesel blend using response surface methodology (RSM)

The synergy of sorbitan monooleate (SMO) and γ-Al2O3 nanoparticles, which was prepared via ultrasonic sonochemistry, as cold-flow improvers (CFI) in B30 biodiesel blend is presented in this work. Response surface methodology (RSM) was employed to study the influence of both CFIs on biodiesel's cold-flow properties, i.e., cloud point (CP), cold-filter plugging point (CFPP), filter blocking tendency (FBT), and precipitate. Based on the result, the relationship between CFI and CP's concentration was best expressed with a quadratic model. Meanwhile, two-factor interaction (2FI) models were more suitable for CFPP, FBT, and precipitate. Based on the result, the most optimum concentration of SMO and γ-Al2O3 nanoparticles were achieved at 0.1% w/v and 50ppm, respectively. At this condition, the predicted values of CP, CFPP, FBT, and precipitate of the sample were 8.52°C, 6.056°C, 7.208, and 564mg/L, respectively. It is believed that SMO's surface-activity and the ability of γ-Al2O3 nanoparticles to form Pickering emulsion were responsible for the inhibition of excessive crystallization of saturated FAME but also enhancing their colloidal stability at low temperature.

Biodiesel synthesis optimization from wet and dry based microalgae chlorella vulgaris by reaction time arrangement

Microalgae have the potential to be used as the raw material for biodiesel synthesis. One of promising microalgae species to be used is Chlorella vulgaris. However, in the process of biodiesel synthesis from microalgae needs to be optimized. In this study, optimization of biodiesel synthesis from wet and dry based microalgae Chlorella vulgaris has been studied. Optimization done by arranges the time of transesterification reaction. Transesterification reaction has been done using KOH catalyst. The reaction time was varied at 20, 40, and 60 minutes. From the results, the highest yields of biodiesel are obtained on the 40 minutes reaction time with biodiesel yield is 75% for wet based microalgae and 62.8% for dry based microalgae. Biodiesel from dry based microalgae Chlorella vulgaris composed by several types of FAME, including saturated FAME such as methyl myristate (4.48%), methyl palmitate (28.3%), and methyl stearate (17.1%), and also composed by unsaturated FAME such as methyl palmitoleate (11.1%) and methyl oleate (39.1%).

Evaluation of the separation of saturated fatty acid methyl esters obtained from additive winterization using a nonionic surfactant

Winterization is one means of improving the low temperature flow properties of biodiesel fuel, by the separation of saturated FAMEs. Additives are also employed to improve separation in the winterization process by modifying the crystallization behavior. This process is referred to as additive winterization. In a previous study, we investigated a novel additive winterization method in which FAMEs are separated without agitation during cooling, allowing improved separation of saturated FAME and unsaturated FAME mixtures. This method is both facile and energy-efficient because vacuum filtration is not required. In this study, we examined the effects of additives (sorbitan mono fatty acids) and agitation on the separation of saturated FAMEs from saturated and unsaturated FAME mixtures via winterization. The additive winterization process resulted in significant improvements in the cloud points of the FAME mixtures following a single separation run, with the cloud point being decreased by 8 K under optimum conditions. In contrast, winterization based on agitation required at least two cycles of sequential cooling, agitation and filtration to obtain similar results. This study therefore highlights the potential of additive winterization using sorbitan mono fatty acid esters to enhance the low-temperature flow properties of biodiesel fuels based on a simple process with reduced energy expenditures.

Mitigating crystallization of saturated FAMEs in biodiesel 6: The binary phase behavior of 1, 2-dioleoyl-3-stearoyl sn-glycerol – Methyl stearate

The derivatives of vegetable oils with specific chemical structures, such as TAG (triacylglycerols) having mixed straight and kinked moieties, have proven very effective in lowering the crystallization of biodiesel. SOO (1, 2-dioleoyl-3-stearoyl sn-glycerol)/MeS (methyl stearate) is part of a series of studies of TAG/FAME (fatty acid methyl ester) binary model systems conducted to establish structure–function relationships of lipid-based cold flow improvers in biodiesel with a particular attention to the effect of molecular symmetry in contrast with a previously published study of the OSO (1, 3-dioleoyl-2-stearoyl sn-glycerol)/MeS binary system. The phase behavior of several SOO/MeS mixtures were investigated at different length scales with XRD (X-ray diffraction), DSC (differential scanning calorimetry) and PLM (polarized light microscope). A complete phase diagram including the transformation lines, crystal structure and microstructure was constructed. The solubility behavior was discussed using a simple thermodynamic model based on the Hildebrand equation and pair interactions. The asymmetric position of the oleic moieties of SOO was shown to be crucial in modifying the thermal transformation behavior of MeS. The findings may be used to design effective crystallization modifiers of biodiesel based on particular structural determinants, and underscores the importance of symmetry in such designs.

Mitigating crystallization of saturated fames in biodiesel: 1. Lowering crystallization temperatures via addition of metathesized soybean oil

The addition of self-MSBO (metathesized soybean oil) to biodiesel significantly depresses the onset temperature of crystallization (Ton). MSBO and self-MTO (metathesized triolein), used as model systems, were separated into their constituent “molecular families” using column chromatography and crystallization fractionation and tested as crystallization modifiers of biodiesel. The results indicate that cis-unsaturation combined with a straight chain moiety is a critical structural architecture for disrupting biodiesel crystallization. The data obtained with TAGs (triacylglycerols) propose that the most effective stereospecificity is when the two fatty acids in the cis-configuration are in the sn-1 and sn-3 positions and a trans-/saturated fatty acid is at the sn-2 position. The conversion of cis-double bonds to trans-double bonds by self-metathesis explains the lowering of Ton of biodiesel. The fractionation of MSBO, leading to a liquid fraction enriched with molecules having cis-unsaturated fatty acids out-performed MSBO in lowering Ton of biodiesel. This knowledge can be used for the design of economical and more functional materials from MSBO and other metathesized vegetable oils using selective and practical fractionation methods. The findings of the study suggest that the use of biodiesel with significant saturated methyl ester content can be extended in colder months of the year.

Mitigating crystallization of saturated FAMES in biodiesel: 5. The unusual phase behavior of a structured triacylglycerol dimer and methyl palmitate binary system

A model binary system made of methyl palmitate (MeP) and (E)-1-(1-(oleoyloxy)-3-(stearoyloxy)propan-2-yl) 18-(1-(oleoyloxy)-3-(stearoyloxy) propan-2-yl) octadec-9-enedioate (dimer, D), a structured triacylglycerol dimer, one of a series of fatty molecules that have been found to significantly reduce the crystallization temperature of biodiesel, was investigated with DSC (differential scanning calorimetry), XRD and PLM (polarized light microscopy). A complex and unusual phase behavior was uncovered for this system. The exclusive orthorhombic crystal packing that was detected by XRD was shown to be guided by the bulky D molecules. The findings are explained by the formation of dimer/methyl palmitate composite units in which the dimer associates with the MeP molecules at its fatty acid branches as well as bridges. This association was initiated in the liquid state where the mobility of MeP and free rotation of the fatty branches of D are favorable. The disruptive effect of D on the packing of the saturated FAME was effective only at low concentrations (<0.10) with the system presenting a eutectic at 5% of D, followed by three stepped transformation lines indicating three concentration regions of defined phases of increasing stability. The findings indicate that the dimer may be an effective cold flow improver of biodiesel but only at concentrations lower than 5%.

Selective fermentation of carbohydrate and protein fractions of Scenedesmus, and biohydrogenation of its lipid fraction for enhanced recovery of saturated fatty acids.

Biofuels derived from microalgae have promise as carbon-neutral replacements for petroleum. However, difficulty extracting microalgae-derived lipids and the co-extraction of non-lipid components add major costs that detract from the benefits of microalgae-based biofuel. Selective fermentation could alleviate these problems by managing microbial degradation so that carbohydrates and proteins are hydrolyzed and fermented, but lipids remain intact. We evaluated selective fermentation of Scenedesmus biomass in batch experiments buffered at pH 5.5, 7, or 9. Carbohydrates were fermented up to 45% within the first 6 days, protein fermentation followed after about 20 days, and lipids (measured as fatty acid methyl esters, FAME) were conserved. Fermentation of the non-lipid components generated volatile fatty acids, with acetate, butyrate, and propionate being the dominant products. Selective fermentation of Scenedesmus biomass increased the amount of extractable FAME and the ratio of FAME to crude lipids. It also led to biohydrogenation of unsaturated FAME to more desirable saturated FAME (especially to C16:0 and C18:0), and the degree of saturation was inversely related to the accumulation of hydrogen gas after fermentation. Moreover, the microbial communities after selective fermentation were enriched in bacteria from families known to perform biohydrogenation, i.e., Porphyromonadaceae and Ruminococcaceae. Thus, this study provides proof-of-concept that selective fermentation can improve the quantity and quality of lipids that can be extracted from Scenedesmus.

Batchwise extraction of methyl linolenate (18:3, ALA) from fatty acid methyl esters derived from soybean and canola oils using silver nitrate/silica gel

The incipient wetness impregnation (IWI) method was used to prepare a series of AgNO3/SiO2 adsorbents that were used for the extraction of unsaturated FAMEs from hexane solutions of methyl soyate and methyl canolate. The AgNO3/SiO2‐IWI adsorbents with the highest AgNO3 loadings (40 or 50% w/w) were the most selective for the removal of methyl linolenate (18:3). For example, extractions with 40% AgNO3/SiO2‐IWI reduce the amount of 18:3 from 7.0% in methyl soyate (1.00 mL) to 1.3% while extracting only 9% of the original FAMEs mixture. The extracted FAMEs fraction has a very high 18:3 (55.6%) and 18:2 (41.9%) composition. This adsorbent maintained its selectivity for 18:3 in at least four successive extractions. Similar extractions of methyl canolate yield a biodiesel that contains much smaller amounts of 18:3. The amounts of 18:3 and 18:2 that are extracted can be controlled by the AgNO3 loading and the amount of AgNO3/SiO2‐IWI that is used.Practical applications: Results of the reported studies show that AgNO3/SiO2 is able to preferentially remove methyl linolenate (18:3, ALA) from methyl soyate and methyl canolate. This batchwise process makes these biodiesels a source of the omega‐3 fatty acid ALA and gives a biodiesel that is less sensitive to oxidative deterioration.FAMEs derived from soybean and canola oils, when treated with AgNO3/SiO2, are separated into a portion that is enriched in 18:3 (ALA) and a biodiesel that contains the more saturated FAMEs.

양송이 배지에서 유래한 Lipase 생산균을 이용한 바이오디젤 생산

A lipase producing bacterium was isolated from button mushroom bed, which showing high clear zone on agar media containing Tributyrin as the substrate. The strain was identified as Burkholderia cepacia by analysis of 16S rDNA gene sequence. Crude lipase (CL) was partially purified from 70% ammonium sulfate precipitation using the culture filtrate of B. cepacia. Immobilized lipases were prepared by cross-linking method with CL from B. cepacia and Novozyme lipase (NL) onto silanized Silica-gel as support. Residual activitiy of the immobilized CL (ICL) and immobilized NL (INL) was maintained upto 61% and 72%, respectively. Biodiesel (Fatty acid methyl ester, FAME) was recovered by transesterification and methanolysis of Canola oil using NaOH, CL and ICL as the catalysts to compare the composition of fatty acids and the yield of FAME. Total FAME content was NaOH 781 mg L-1, CL 681 mg L-1 and ICL 596 mg L-1, in which the highest levels of FAME was observed to 50% oleic acid (C18:1) and 22% stearic acid (C18:0). In addition, the unsaturated FAME (C18:1, C18:2) decreased, while saturated FAME (C16:0, C18:0) increased according to increasing the reaction times with both CL and ICL, supporting CL possess both transesterification and interesterification activity. When reusability of ICL and INL was estimated by using the continuous reaction of 4 cycles, the activity of ICL and INL was respectively maintained 66% and 79% until the fourth reaction.

Extraction of extracellular lipids from chemoautotrophic bacteria Serratia sp. ISTD04 for production of biodiesel

A CO2 sequestering bacterial strain, Serratia sp. ISTD04, that produces a significant amount of extracellular lipids was isolated from marble mine rocks. 14C labeling analysis revealed that the rate of assimilation of CO2 by the strain is 0.756×10−9μmolCO2fixedcell−1h−1. It was found to produce 466mg/l of extracellular lipid which was characterized using 1H NMR. After transesterification of lipids, the total saturated and unsaturated FAME was found to be 51% and 49% respectively. The major FAME contained in the biodiesel were palmitic acid methyl ester (C16:0), oleic acid methyl ester (C18:1) and 10-nonadecenoic acid methyl ester (C19:1). Biodiesel produced by Serratia sp. ISTD04 is balanced in terms of FAME composition of good quality. It also contained higher proportion of oleic acid (35%) which makes it suitable for utilization in existing engines. Thus, the strain can be harnessed commercially to sequester CO2 into biodiesel.

Cold Flow Properties and Kinematic Viscosity of Biodiesel

Biodiesel is a substitute diesel fuel produced from vegetable oils or animal fats by trans-esterification in the presence of a catalyst. Due to its environmental friendliness, its use is becoming necessary in all regions, however, there are problems associated with its fluidity in cold temperatures. This paper examines the cold flow properties as well as the kinematic viscosity of produced biodiesels. The review shows that both properties are affected by the length of the carbon chain and degree of saturation. However, these can be improved by blending either with petro-diesel or less saturated FAME, as well as the use of some additives.

Bioprospecting the thermal waters of the Roman baths: isolation of oleaginous species and analysis of the FAME profile for biodiesel production

The extensive diversity of microalgae provides an opportunity to undertake bioprospecting for species possessing features suited to commercial scale cultivation. The outdoor cultivation of microalgae is subject to extreme temperature fluctuations; temperature tolerant microalgae would help mitigate this problem. The waters of the Roman Baths, which have a temperature range between 39°C and 46°C, were sampled for microalgae. A total of 3 green algae, 1 diatom and 4 cyanobacterial species were successfully isolated into ‘unialgal’ culture. Four isolates were filamentous, which could prove advantageous for low energy dewatering of cultures using filtration.Lipid content, profiles and growth rates of the isolates were examined at temperatures of 20, 30, 40°C, with and without nitrogen starvation and compared against the oil producing green algal species, Chlorella emersonii. Some isolates synthesized high levels of lipids, however, all were most productive at temperatures lower than those of the Roman Baths. The eukaryotic algae accumulated a range of saturated and polyunsaturated FAMEs and all isolates generally showed higher lipid accumulation under nitrogen deficient conditions (Klebsormidium sp. increasing from 1.9% to 16.0% and Hantzschia sp. from 31.9 to 40.5%). The cyanobacteria typically accumulated a narrower range of FAMEs that were mostly saturated, but were capable of accumulating a larger quantity of lipid as a proportion of dry weight (M. laminosus, 37.8% fully saturated FAMEs). The maximum productivity of all the isolates was not determined in the current work and will require further effort to optimise key variables such as light intensity and media composition.

Contents of Volume 52 (2003)

A CO2 sequestering bacterial strain, Serratia sp. ISTD04, that produces a significant amount of extracellular lipids was isolated from marble mine rocks. 14C labeling analysis revealed that the rate of assimilation of CO2 by the strain is 0.756 × 10−9 μmol CO2 fixed cell−1 h−1. It was found to produce 466 mg/l of extracellular lipid which was characterized using 1H NMR. After transesterification of lipids, the total saturated and unsaturated FAME was found to be 51% and 49% respectively. The major FAME contained in the biodiesel were palmitic acid methyl ester (C16:0), oleic acid methyl ester (C18:1) and 10-nonadecenoic acid methyl ester (C19:1). Biodiesel produced by Serratia sp. ISTD04 is balanced in terms of FAME composition of good quality. It also contained higher proportion of oleic acid (35%) which makes it suitable for utilization in existing engines. Thus, the strain can be harnessed commercially to sequester CO2 into biodiesel.