Fatty Acid Methyl Ester Profiles Research Articles

Selecting the most effective plant growth-promoting bacteria from oil palm (Elaeis guineensis Jacq) roots

A total of 30 bacterial isolates were isolated from soil, rhizoplane, and internal tissue of oil palm roots. The isolates were qualitatively tested for their potential to fix N2, solubilize inorganic P and K, and produce phytohormone indole-3-acetic acid. Of the 30 isolates, six isolates were able to exhibit multiple beneficial traits. All six isolates were then identified based on fatty acid methyl esters profile as Escherichia coli strain EX2, Serratia sp. strain EN1, Pantoea ananatis strain EN3, Bacillus sp. strain EN5, Pantoea ananatis strain EN8 and Pantoea sp. strain EN9. Subsequently, all shortlisted isolates were evaluated for plant growth-promoting potential by using shallot as a test plant. The plant test showed no significant difference (p>0.05) between inoculated and uninoculated plants except for Pantoea sp. strain EN9 inoculation which increased significantly (p<0.05) total root length over uninoculated control. Host specificity and IAA capacity of the isolates may be among the important factors affecting their effectiveness in plant growth promotion.
 J Bangladesh Agril Univ 17(3): 344–348, 2019

Improved transesterification conditions for production of clean fuel from municipal wastewater microalgae feedstock

Abstract Microalgae have great potential to be used as feedstock for biofuel production. Municipal wastewater is an economically appealing culture medium to produce microalgae. Downstream processing of wastewater-adapted microalgae, i.e. transesterification of extracted lipid, needs to be more investigated due to the difference between lipid profile of pure culture microalgae and wastewater-adapted microalgae. Based on quantitative parameters of acidity, acid value, and triglyceride content it was indicated that free fatty acid and triglyceride contents of wastewater-adapted algal lipid were between the two limits i.e pure microalgal lipid and vegetable oil. Optimal transesterification conditions for wastewater-adapted algal lipid were investigated in terms of acid-catalyzed versus alkaline-catalyzed reactions, temperature and reaction time, and the type of catalyst. It was found that acid-catalyzed transesterification at 70 °C for 35 h using sulfuric acid as the catalyst is required to achieve the highest percentage of fatty acid methyl esters of 53.9 ± 9.6% in the end product. This is quite different from reaction conditions recommended for pure microalgal lipid and vegetable oil transesterification. These operating conditions resulted in a dominant fatty acid methyl ester profile of palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid in the product that satisfied international standards specified for biodiesel. The results of this study customizes the transesterification reaction conditions for wastewater-adapted algal lipid and is one step forward towards commercial production of clean fuel from microalgae feedstock obtained from wastewater.

A facile and mild one-pot process for direct extraction of lipids from wet energy insects of black soldier fly larvae

The insect lipids were recovered using one-pot manner via a high speed homogeniser from the wet black soldier fly larvae as the novelty lipid feedstocks at room temperature and pressure in this study. The comparison of the influences of different conditions (solvent types, solute-solvent ratios, water contents, and homogenization intensities) on the lipid extraction efficiency and lipid compositions were studied and evaluated. The results indicated that all the binary solvents tested in this work present a higher extraction capacity (70–74%) than the monophasic solvent increasing two-fold the lipid extraction yield. There was a significant difference between the 30.96% and 86.67% in saponifiable lipids purity for different extraction solvent systems. The effects of water contents on the lipid extraction process for relatively low contents of non-polar solvent in the binary extraction solvents system were greater than that of high contents of non-polar solvent. However, fatty acid methyl esters profiles from the energy biomass indicate that relevant fatty acids were present in all solvent extracts, with no significant variation in the FAME composition provided for different investigated conditions. Key characteristics of the recovered lipids indicate that the pretreatment process-cell disruption was a critical step in the recovery of intracellular lipids from the wet biomass, which significantly enhancing the lipid extraction process. In combination with SEM images of the damaged cells, the precise mechanism of cell disruption via the high speed homogeniser was comprehensively described. At last, the kinetic model (r2 ≥ 0.9937) of lipid extraction from the ruptured cell at various homogenization intensities (6000–14000 rpm) was explored in preliminary. The extraction constants were determined for the lipid extraction process, ranging from 0.0531 to 0.0681 s−1. Considering its energy-efficiency and potential for scale-up, the one-pot manner may be a promising method to achieve industrial-scale lipid extraction from wet biomass.

RETRACTED: A Sugarcane-Bagasse-Based Adsorbent Employed for Mitigating Eutrophication Threats and Producing Biodiesel Simultaneously

Eutrophication is an inevitable phenomenon, and it has recently become an unabated threat. As a positive, the thriving microalgal biomass in eutrophic water is conventionally perceived to be loaded with myriad valuable biochemical compounds. Therefore, a sugarcane-bagasse-based adsorbent was proposed in this study to harvest the microalgal biomass for producing biodiesel. By activating the sugarcane-bagasse-based adsorbent with 1.5 M of H2SO4, a highest adsorption capacity of 108.9 ± 0.3 mg/g was attained. This was fundamentally due to the surface potential of the 1.5 M H2SO4 acid-modified sugarcane-bagasse-based adsorbent possessing the lowest surface positivity value as calculated from its point of zero charge. The adsorption capacity was then improved to 192.9 ± 0.1 mg/g by stepwise optimizing the adsorbent size to 6.7–8.0 mm, adsorption medium pH to 2–4, and adsorbent dosage to 0.4 g per 100 mL of adsorption medium. This resulted in 91.5% microalgae removal efficiency. Excellent-quality biodiesel was also obtained as reflected by the fatty acid methyl ester (FAME) profile, showing the dominant species of C16–C18 encompassing 71% of the overall FAMEs. The sustainability of harvesting microalgal biomass via an adsorption-enhanced flocculation processes was also evidenced by the potentiality to reuse the spent acid-modified adsorbent.

Benchtop flow NMR spectroscopy as an online device for the in vivo monitoring of lipid accumulation in microalgae

The sustainable production of lipids by microalgae is widely developed among the bioprocess community targeting various applications such as feed, food, health or bioenergy. The cultivation of microalgae needs dedicated systems with the optimal illumination geometry. Performing non-invasive online analyses on these bioprocesses is limited to few analytical techniques, often based on optical properties and can however rarely be related to intracellular products. The real-time knowledge of the lipids accumulation in microalgae is –in this case– not possible. In this article, the proof-of-concept that the recent benchtop NMR spectroscopy device can be used for the non-invasive and selective detection of lipids inside microalgae cells is carried out. Three cultures of Nannochloropsis gaditana were analyzed in flow conditions. The relative quantitative feature is confirmed by the correlation with a reference technique classically used for lipid analysis, i.e. the FAME (Fatty Acid Methyl Ester) profiling by gas chromatography.

Biological fixation of carbon dioxide and biodiesel production using microalgae isolated from sewage waste water.

The present research investigates potential of microalgae isolated from sewage treatment plant to utilize sodium bicarbonate as carbon source for CO2 sequestration and biodiesel production. Eight algal isolates were isolated from waste water of sewage treatment plant, Amity University Haryana, India. The most potent algal isolates were identified and characterized on the basis of growth and lipid content. The efficient isolates ASW1 and ASW2 were identified as Chlorella sp. and Arthronema sp. by 18srRNA and 16srRNA sequencing method. In both isolates, maximum growth was observed under 20-W fluorescent bulb (3500 flux light intensity) with continuous light cycle of 24h at pH9.0 and 25°C on the 20th day of incubation period. CO2 utilization efficiency of both algal isolates were observed in terms of total CO2 consumption rate. Under optimized culture conditions, total lipid content and lipid yield was higher in Arthronema sp. (180mgl-1; 32.14%) as compared to Chlorella sp. (98mgl-1; 29.6%) in 50mM NaHCO3. Transesterified lipids were analysed by GC-MS. The fatty acid methyl ester profile of Arthronema sp. was 34.42% saturated and 65.58% unsaturated fatty acid. Chlorella sp. produces 29.80% saturated and 70.20% unsaturated fatty acid. In both isolates, C16 and C18 fatty acids dominated, which is a promising component for biodiesel. Graphical abstract.

A green garlic (Allium sativum L.) based intercropping system reduces the strain of continuous monocropping in cucumber (Cucumis sativus L.) by adjusting the micro-ecological environment of soil.

The continuous cropping obstacle of cucumber (Cucumis sativus L.) under facility cultivation is more prevalent in China. This is associated with an imbalance in soil microbial and ecological environment in long-term monocultures. It was postulated that intercropping with green garlic would relieve the continuous cropping obstacle of cucumber by altering the soil micro-ecology status. A pot-based experiment was conducted to investigate the green garlic-cucumber intercropping and cucumber monocropping systems. The results showed that the cucumber shoot biomass was improved by intercropping with green garlic. However, the population of soil bacteria and actinomycetes increased, while the fungal population decreased. The fatty acid methyl ester (FAME) profiles indicated that soil contained more fungal FAME biomarkers (18:1ω9c, 18:2ω6, 9) and higher fungal:bacterial ratio in the monoculture system, whereas clustering of more bacterial FAME biomarkers (cy17:0, cy19:0, 16:1ω7c10, Me16:0, 10Me17:0, 10Me18:0) was observed under intercropping conditions. Moreover, significantly (P < 0.05) higher soil invertase and alkaline phosphatase activities, organic matter, and available N, P and K contents were observed under intercropping systems. These were high in both bulk and rhizosphere soils in the intercropping system when compared to monocropping system. These findings suggest that intercropping with green garlic can alleviate continuous cropping obstacle of cucumber by improving the diverse composition of soil microbial community, enzyme activities, and nutrient availability.

Isolation and Characterization of Microalgae from Diverse Pakistani Habitats: Exploring Third-Generation Biofuel Potential

Production of microalgae as feedstock for biofuels must deal with a number of challenges including constraints imposed by local conditions. One solution is to use indigenous strains adapted to local climatic conditions. The present report describes the isolation, identification, and characterization of 32 microalgal strains from different ecological habitats: desert freshwater channels, northern region, and saline regions of Pakistan. The effects of temperature on algal growth rates, biomass productivity, and lipid content were determined through growth at 12, 20, and 35 °C for 15 days under 2% CO2 Responses to temperature varied among species with 20 °C being the optimum temperature in general, although, exceptionally, the best overall growth rate was found for strain S29 (0.311 d−1) at 12 °C. In some cases high biomass productivity was observed at 35 °C, and, depending upon the strain, the maximum lipid content was obtained at different temperatures, including 12 °C. Fatty acid methyl ester (FAME) analysis showed that the major fatty acids present were palmitic, stearic, oleic, linoleic, and linolenic. Oleic acid (C18:1) was the predominant fatty acid, with the specific FAME profile varying with strain. Thus, there is a rich diversity of microalgal strains native to Pakistan, some of which, characterized here, could be suitable for biodiesel production or other biotechnological applications.

Amelioration of biomass and lipid in marine alga by an endophytic fungus Piriformospora indica

BackgroundMany studies have been carried out on the growth-modulating efficiency of plants by the colonization of an endophytic fungus Piriformospora indica. However, studies involving the co-culture of alga with endophytic fungal strains for enhanced biodiesel production are rare. In this study, the interaction between P. indica and Parachlorella kessleri-I, a marine algal strain, was assessed at metabolic level.ResultsIn association with an endophytic fungus, the algal biomass enhanced from 471.6 to 704 mg/L, and the fatty acid methyl ester (FAME) profile of P. kessleri-I increased substantially. In case of FAME profile of co-cultured P. kessleri-I, two essential components of biodiesel, i.e. elaidic acid and oleic acid, increased by 1.4- and 1.8-fold, respectively. To ascertain changes in the metabolic profile of P. kessleri-I by P. indica co-culture, gas chromatography–mass spectrometry (GC–MS)-based untargeted metabolomics study was performed to identify the metabolites involved; and differential nature of the essential metabolites was also confirmed using HPLC and LC–MS. Significant modulation of the bioactive metabolites such as succinate, oxo-propanoate, l-alanine, glutamate, acetate and 1,2 propanediol, hydroxy butane was observed.ConclusionThe metabolites like glutamate and succinate that usually belong to the GABA shunt pathway were observed to be upregulated. The pathway links nitrogen metabolism and carbon metabolism, thus influencing the growth and lipid profile of the algae. These differential metabolites thus indicated the important commensal association between the endophytic fungus and autotrophic marine alga, and established that endophytic fungus can be handy for the sustainability of algal biofuel industries.

Biomass and lipid productivity of Dunaliella tertiolecta in a produced water-based medium over a range of salinities

Dunaliella tertiolecta was grown in an oilfield-produced water-based medium (PW) over a wide range of salinities (30–210 g total dissolved solids (TDS) L−1). Similar biomass productivity was observed from 30 to 120 g TDS L−1 with decreased growth at the higher salinities of 180 and 210 g TDS L−1. Biomass productivity in all PW conditions was higher than in the commercial f/2 algae growth medium (35 g TDS L−1), which may have been the result of higher bicarbonate concentration of the PW (20 vs. 2 mM). In the lower salinity conditions (30 and 60 g TDS L−1), the total lipid component of biomass was highest at about 35–40% coinciding with nutrient depletion (nitrogen and phosphorus). The lipid fraction then decreased in the nutrient-depleted media as the culture added biomass. Early lipid enrichment in the 30 and 60 g TDS L−1 conditions coincided with peak pH which likely represented maximum bicarbonate uptake. The higher salinities tested (120, 180, and 210 g TDS L−1) displayed a different pattern of an increasing lipid fraction of biomass in a nutrient-depleted media until stationary phase (peak total lipid fraction approximately 31–34%). Fatty acid methyl ester profiles (FAME) at all salinities tested were dominated by C16:0 with a lesser amount of unsaturated C18 carbon chains and should produce a quality biodiesel. The characteristic of the FAME did not vary considerably by salinity. Increased biomass and lipid productivity might result from utilizing hypersaline PW with high bicarbonate concentrations (often already present) for algae cultivation.

Microbial lipids from cellulolytic oleaginous fungus Penicillium citrinum PKB20 as a potential feedstock for biodiesel production

Microbial lipids derived from oleaginous fungi are considered as an alternative feedstock for biodiesel production. We attempt to isolate a cellulolytic oleaginous fungi as a potential feedstock for biodiesel production. The fungus was identified by 5.8 S-ITS rRNA gene sequencing. The extracellular enzyme activities were recorded after every 24 h for 7 days. Nile red staining and fluorescence microscopy was used to visualise the lipid bodies within the fungal hyphae. A renewable heterogeneous base catalyst derived from Musa balbisiana cola peels was used for the transesterification of Penicillium citrinum PKB20 derived oil into biodiesel. GC-MS analysis was used to analyse the fatty acid methyl esters (FAME) profile of the transesterified lipids. Penicillium citrinum PKB20 was isolated from detritus rich soil of Assam, India. The endoglucanase, xylanase and β-glucosidase enzyme activities were found to be 292.83 ± 0.29, 111.72 ± 0.45 and 6.54 ± 0.13 U/mg respectively. The specific enzyme activity for extracellular lipase was found to be 3.12 ± 0.16 U/mg. It could accumulate up to 60.61% of lipids in nitrogen-limited medium (7.34 ± 0.45 g/L biomass production). The extracted lipids were converted to biodiesel with 89.3% conversion efficiency. The predominant fatty acids were oleic acid (30.09%), palmitic acid (20.25%) and linoleic acid (33.14%) suggesting a balance between oxidative stability and cold flow properties for suitable biodiesel quality. Penicillium citrinum PKB20 was found to be a potential feedstock for biodiesel production with desirable fuel properties. The cellulolytic nature could be utilised for simultaneous lipid production directly on cellulosic substrates.

Fatty Acid Methyl Ester (FAME) Profiling Identifies Carbapenemase-Producing Klebsiella pneumoniae Belonging to Clonal Complex 258

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is one of the most extensively antibiotic-resistant pathogens encountered in the clinical setting today. A few studies to-date suggest that CRKP and carbapenem-susceptible K. pneumoniae (CSKP) differ from one another not only with respect to their underlying genetics, but also their transcriptomic and metabolomic fingerprints. Within this context, we characterize the fatty acid methyl ester (FAME) profiles of these pathogens in vitro. Specifically, we evaluated the FAME profiles of six Klebsiella pneumoniae carbapenemase (KPC)-producing isolates belonging to the CC258 lineage (KPC+/258+), six KPC-producing isolates belonging to non-CC258 lineages (KPC+/258−), and six non-KPC-producing isolates belonging to non-CC258 lineages (KPC−/258−). We utilized a single-step sample preparation method to simultaneously lyse bacterial cells and transesterify the lipid fraction, and identified 14 unique FAMEs using gas chromatography-mass spectrometry. The machine learning algorithm Random Forest identified four FAMEs that were highly discriminatory between CC258 and non-CC258 isolates (9(Z)-octadecenoate, 2-phenylacetate, pentadecanoate, and hexadecanoate), of which three were also significantly different in relative abundance between these two groups. These findings suggest that distinct differences exist between CC258 and non-CC258 K. pneumoniae isolates with respect to the metabolism of both fatty acids and amino acids, a hypothesis that is supported by previously-acquired transcriptomic data.

Effects of LED-controlled spatially-averaged light intensity and wavelength on Neochloris oleoabundans growth and lipid composition

This study evaluated variations in Neochloris oleoabundans' growth rate and biochemical characteristics (fatty acid methyl ester (FAME) profile and lipid granule properties) in response to light-emitting diodes (LEDs) at a range of spatially-averaged light intensities (LISA) in either the red or white spectra. The red-light spectra (630–700 nm) yielded the greatest proportions of total lipids (25.2 ± 0.2 wt%) as well as monounsaturated fatty acids (MUFAs) such as C16:1 and C18:1, producing a high-quality FAMEs profile for biodiesel production. Using white and red spectra, the half-maximum-rate light irradiance (KL) was 35 and 37 μE m−2 s−1 and the half-inhibition-rate light irradiance (KI) was 299 and 502 μE m−2 s−1, respectively. The greater red-light KI value suggests that N. oleoabundans is less sensitive to photoinhibition by light of that spectra. Transmission electron microscope (TEM) images also showed enlarged lipid bodies in algal cells grown under high light intensities in the red spectra, a clear advantage for lipid production. These results demonstrate that control over light wavelength is a powerful tool for the production of high-quality fatty acids in microalgae could be a viable and sustainable medium for algae cultivation.

Augmenting Fremyella diplosiphon Cellular Lipid Content and Unsaturated Fatty Acid Methyl Esters Via Sterol Desaturase Gene Overexpression.

Cyanobacteria have immense prospective as a platform for renewable energy; however, a major barrier in achieving optimal productivity is the low lipid yield. Fremyella diplosiphon, a model cyanobacterium, is an ideal biofuel agent due to its desirable fatty acid methyl esters (FAMEs). To enhance lipid content, we overexpressed the sterol desaturase (SD) gene in F. diplosiphon B481 wild type by genetic transformation. This effort resulted in a transformant (B481-SD) with a 64-fold increase in the SD gene at the mRNA transcript level, with no loss in growth and pigmentation. The transformant was persistently grown for over 32 generations indicating long-term stability and vitality. We observed 27.3% and 23% increases in total lipid content and unsaturated FAMEs respectively in B481-SD transesterified lipids with methyl octadecadienoate as the most abundant unsaturated component. In addition, we detected an 81% increase in FAME composition in the transformant compared with the wild type. Theoretical physical and chemical properties confirmed a FAME profile with very high cetane number (65.972-67.494) and oxidative stability (50.493-18.66h) in the engineered strain. Results of the study offer a promising approach to augment F. diplosiphon total lipid content and unsaturated FAMEs, thus paving the way to enhance biofuel capacity of the organism.

Effect of Immobilization Method on the Growth of &lt;i&gt;Chlorella vulgaris&lt;/i&gt; and Fatty Acid Profile for Biodiesel Production

The aim of this research is to study the immobilization effect on growth cell of microalgae Chlorella vulgaris. The comparison of lipid production between immobilized microalgae and free cell culture was also studied and the fatty acid methyl ester for biodiesel production was identified in this research. Four important steps were done in this research which included microalgae cultivation, harvesting method by immobilization, lipid extraction and transesterification of oil. In the immobilization method, the combination of matrix system of sodium alginate and sodium carboxymethylcellulose (SA and CMC) gave the highest number of cells of microalgae after the 9th day of the cultivation process. However, the immobilized microalgae matrix system of SA at volumetric ratio of 0.3:1 showed better results for extraction of oil, attaining an oil yield percentage of 46% compared with other matrix systems studied; SA + CA + CMC (43.00%), SA + CA (41.19%), SA + CMC (40.38%) and free cell culture (42.57%). Furthermore, the fatty acids methyl ester profile of the extracted oil showed high potential for biodiesel production. The results proved that the immobilization of microalgae had improved the oil yield and fatty acid composition as compared to the free cell culture, which may have useful application for the biofuel industry.

Fe2O3 nanocatalyst aided transesterification for biodiesel production from lipid-intact wet microalgal biomass: A biorefinery approach

Biodiesel production from non-edible feedstock such as microalgae is gaining importance in present day, as they do not interfere with global food economy in addition to higher photosynthetic efficiency as compared to plants. Fresh water grown Neochloris oleoabundans UTEX 1185 is considered as a potential source for biodiesel production. The present study investigated different direct lipid extraction process from wet microalgal biomass through autoclaving, microwave, and ultrasonication pretreatments. Autoclave treatment showed a higher efficiency for lipid extraction as compared to other two pretreatments. Furthermore, transesterification process was carried out in presence of Fe2O3 catalyst and compared with conventional acid (HCl) and base (NaOH) catalysts. Fe2O3 nanoparticles used were synthesized from extract of Hibiscus rosa-sinensis by green procedure. The synthesized Fe2O3 catalyst played an important role in improving the biodiesel yield up to 81%, which is higher than that obtained with HCl (64%) and NaOH (48%). Thereafter transesterification process parameter like catalyst content, reaction temperature and reaction time were optimized and finally 86% biodiesel yield was obtained. Fatty acid methyl esters (FAME) profile analysis and fuel properties revealed the suitability of algal lipid for biodiesel production. 20.2% w/w of carbohydrate present in lipid extracted microalgal biomass was further converted into biohydrogen by dark fermentation and bioethanol under anaerobic condition using acidogenic mixed consortia and Saccharomyces cerevisiae (INVSC-1), respectively. The life cycle assessment study of the overall process was also done.

Fatty acid profile of peel and pulp of Spanish jujube (Ziziphus jujuba Mill.) fruit

The fatty acid methyl esters (FAMEs) profiles of fruit peel and pulp of 4 Spanish cultivars of Ziziphus jujuba were studied. The FAMEs profile of the cultivar ‘GAL’ was studied under two farming practices, (i) organic, ‘GAL-E’ and conventional, ‘GAL-T’. Eleven FAMEs were identified, the predominant ones were cis-palmitoleic acid (pulp) and oleic and palmitic acid (peel). When comparing the FAMEs profiles between organic and conventional ‘GAL’ peel jujube fruits, the ‘GAL-E’ (organic) presented a higher unsaturated/saturated ratio than the ‘GAL-T’ cultivar (conventional), while this relationship in the pulp was the opposite. The ‘DAT’ cultivar was interesting for its high palmitoleic acid content while the ‘GAL-E’ and ‘GAL-T’ cultivars had high contents of oleic, palmitic and linoleic acids. The LDA (linear discriminant analysis) model showed that the FAMEs contents could be used to discriminate the studied cultivars, and the agricultural practice, because all groups were clearly separated with no overlaps.

Safflower Biodiesel: Improvement of its Oxidative Stability by Using BHA and TBHQ

Biodiesel is gaining more and more importance due to environmental issues. This way, alternative and sustainable crops as new biofuel sources are demanded. Safflower could be a sustainable raw material for biodiesel production, showing one disadvantage (as many biodiesels from vegetable oils), that is, a short oxidative stability. Consequently, the use of antioxidants to increase this parameter is mandatory. The aim of this research work was to assess the effect of two antioxidants (butylated hydroxyanisole, BHA, and tert-butylhydroquinone, TBHQ) on the oxidative stability of safflower biodiesel, which was characterized paying attention to its fatty acid methyl ester profile. For oxidative stability, the Rancimat method was used, whereas for fatty acid profile gas chromatography was selected. For the remaining parameters, the methods were followed according to the UNE-EN 14214 standard. The overall conclusion was that safflower biodiesel could comply with the standard, thanks to the use of antioxidants, with TBHQ being more effective than BHA. On the other hand, the combined use of these antioxidants did not show, especially at low concentrations, a synergic or additive effect, which makes the mixture of these antioxidants unsuitable to improve the oxidative stability.

Identification of Green Alga Chlorella vulgaris Isolated from Freshwater and Improvement Biodiesel Productivity via UV Irradiation

Chlorella vulgaris was isolated from the Nile River, Qalubia Governorate, Egypt, for possible use in biodiesel production. BG-II nutrient growth media was used for isolation and laboratory growth. Identification was performed via 18S rRNA gene amplification, followed by sequencing. The alga was exposed to UVC (254 nm) for 15, 30, and 45 s to improve dry weight accumulation and to increase the oil production. Daily measurements of dry weight (g·l-1) were performed; oil content and volumetric lipid productivity were also determined. UV-C exposure led to an increase in the volumetric lipid productivity by 27, 27.3, and 32.4 mg·l-1·d-1 with 15, 30, and 45 s, respectively, as compared with the control, which resulted in 18 mg·l-1·d-1. Of the examined mutants, the one with the highest productivity was re-irradiated by UV-C (254 nm) for 15, 30, 45, and 60 s. For 15 s of exposure time, the oil content increased to 34%, while it was 31% at 30 s; further, it decreased to 22% at 45 and 60 s exposures. The fatty acid methyl ester profile was 82.22% in the first mutant at 45 s, compared with the wild strain that contained a total of 66.01% of FAs. Furthermore, the highest levels of polyunsaturated fatty acid methyl ester were observed in the mutant exposed for 45 s, and it reached 11.41%, which reduced the cetane number to 71.3.

Recovery of Fatty Acids from Mineralogic Mars Analogs by TMAH Thermochemolysis for the Sample Analysis at Mars Wet Chemistry Experiment on the Curiosity Rover.

The Mars Curiosity rover carries a diverse instrument payload to characterize habitable environments in the sedimentary layers of Aeolis Mons. One of these instruments is Sample Analysis at Mars (SAM), which contains a mass spectrometer that is capable of detecting organic compounds via pyrolysis gas chromatography mass spectrometry (py-GC-MS). To identify polar organic molecules, the SAM instrument carries the thermochemolysis reagent tetramethylammonium hydroxide (TMAH) in methanol (hereafter referred to as TMAH). TMAH can liberate fatty acids bound in macromolecules or chemically bound monomers associated with mineral phases and make these organics detectable via gas chromatography mass spectrometry (GC-MS) by methylation. Fatty acids, a type of carboxylic acid that contains a carboxyl functional group, are of particular interest given their presence in both biotic and abiotic materials. This work represents the first analyses of a suite of Mars-analog samples using the TMAH experiment under select SAM-like conditions. Samples analyzed include iron oxyhydroxides and iron oxyhydroxysulfates, a mixture of iron oxides/oxyhydroxides and clays, iron sulfide, siliceous sinter, carbonates, and shale. The TMAH experiments produced detectable signals under SAM-like pyrolysis conditions when organics were present either at high concentrations or in geologically modern systems. Although only a few analog samples exhibited a high abundance and variety of fatty acid methyl esters (FAMEs), FAMEs were detected in the majority of analog samples tested. When utilized, the TMAH thermochemolysis experiment on SAM could be an opportunity to detect organic molecules bound in macromolecules on Mars. The detection of a FAME profile is of great astrobiological interest, as it could provide information regarding the source of martian organic material detected by SAM.