Fatty Acid Methyl Ester Profiles Research Articles

HETEROGENEOUS CATALYSIS USING BENTONITE-SUPPORTED Fe-Co-Ni TRIMETALLIC NANOPARTICLES

Herein, the synthesis and characterization of a bentonite-supported Fe-Co-Ni trimetallic nanocatalyst applied in transesterification reaction was reported. The synthesized heterogeneous catalyst was used to investigate the production of biodiesel by varying the reaction parameters using Box-Behnken design response surface methodology (RSM-BBD). An optimum biodiesel yield of 95.2 % was obtained at methanol to oil ratio of 10:1, reaction time of 2 hours, reaction temperature of 55 and catalyst concentration of 5 % (w/w of the oil). The biodiesel produced was later analysed using GC-MS analysis and the results shows a fatty acid methyl esters (FAME) profile that confirms the presence of biodiesel.

Characterization of grapevine fungal canker pathogens Fatty Acid Methyl Ester (FAME) profiles

ABSTRACT Fatty acid methyl ester (FAME) analyses can be useful for distinguishing microbial species. This study conducted FAME analyses on 14 fungal species known to cause grapevine trunk diseases. FAME profiles were dominated by oleic acid, albeit profiles were characteristic enough to separate species. Discriminant analyses suggested that palmitoleic acid/sapienic acid, pentadecylic acid, and an unsaturated 17-carbon fatty acid (17:1ω8 c)could explain 79.8% of the variance in the profiles among species in the first three discriminant functions. FAME profile libraries were created for use in a commercialized software, which was able to accurately identify isolates to the species level, with a low rate (9.4%) of samples to be reassessed. Dendrograms created using neighbor-joining cluster analyses with data from FAME profiles were compared with those using internal transcribed spacer (ITS) region sequences. This revealed that FAME profiles, albeit useful for tentative species identification, should not be used for determining phylogenetic relationships because the dendrograms were significantly unconcordant. Regardless, these results demonstrated the potential of FAME analyses in quickly and initially identifying closely related fungal species or confirming conclusions from other species identification techniques that would require independent validation.

Ultrasound-assisted biodiesel synthesis by in–situ transesterification of microalgal biomass: Optimization and kinetic analysis

In-situ transesterification of microalgal biomass has emerged as efficient technique for biodiesel synthesis, as it eliminates the step of lipid extraction. In this paper, we report new insights of in-situ transesterification with application of sonication. The major objectives of our study were: (1) optimization of biomass pretreatment, (2) statistical optimization of transesterification parameters, (3) kinetic and Arrhenius analysis, and (4) determination of fuel properties of biodiesel. Lyophilized microalgal biomass with base catalyst NaOH resulted in the highest biodiesel yield of 31.6% w/w dry biomass. The statistical optimization resulted in biodiesel yield of 33.0 ± 1.1% w/w for parameters: catalyst loading = 1.7% (w/w biomass), methanol to biomass ratio = 30 (v/w), temperature = 50 °C and reaction time = 50 min. Application of sonication during in-situ transesterification showed 60–80% rise in kinetic constants with reduction in activation energy from 26.55 to 21.52 kJ/mol and rise in biodiesel yield from 33.0% to 39.9% w/w dry biomass. These results are attributed to intense micro-convection generated by sonication that not only enhances lipid extraction from biomass but also causes fine emulsification of reaction mixture that enhances the interfacial area. Using fatty acid methyl ester profile of biodiesel, the fuel properties were determined as: Higher heating value = 39.474, cetane number = 54.232, iodine value = 84.306, kinematic viscosity = 3.696, density = 0.875, saponification value = 202.295. These properties are satisfactory are within the prescribed American standards for automotive fuels.

Mesorhizobium comanense sp. nov., isolated from groundwater.

Strain 3P27G6T was isolated from an artesian well connected to the thermal water basin of Comano Terme, Province of Trento, Italy. In phylogenetic analyses based on multilocus sequence analysis, strain 3P27G6T clustered together with Mesorhizobium australicum WSM2073T. Genome sequencing produced a 99.51 % complete genome, with a length of 7 363 057 bp and G+C content of 63.53 mol%, containing 6897 coding sequences, 55 tRNA and three rRNA. Average nucleotide identity analysis revealed that all distances calculated between strain 3P27G6T and the other Mesorhizobium genomes were below 0.9, indicating that strain 3P27G6T represents a new species. Therefore, we propose the name Mesorhizobium comanense sp. nov. with the type strain 3P27G6T (=DSM 110654T=CECT 30067T). Strain 3P27G6T is a Gram-negative, rod-shaped, aerobic bacterium. Growth condition, antibiotic susceptibility, metabolic and fatty acid-methyl esters profiles of the strain were determined. Only few nodulation and nitrogen fixation genes were found in the genome, suggesting that this strain may not be specialized in nodulation or in nitrogen fixation.

A machine learning approach in drying of microalga Chlorella minutissima in a single rotary drum dryer for biodiesel production

Drying of Chlorella minutissima slurry was carried out in a single rotary drum dryer at varied drum surface temperature and rotational speed to achieve higher lipid yield for biodiesel conversion. Residual moisture content and lipid yield of the corresponding drum speed and drum surface temperature were mapped. Application of the machine learning tool classified the range of residual moisture content to be <10% (wet biomass) for high lipid recovery with an accuracy of 97%. Based on the drying time, lipid recovery, and energy consumption, drying at 80°C drum surface temperature with 0.3 rpm resulted ˃90% lipid recovery as compared to the bone-dried biomass. The energy consumption of 7.328 kWh for 1 kg of dried biomass was recorded with profound reduction in drying time as compared to oven and tray drying of algal slurry. The fatty acid methyl ester profile of C. minutissima biodiesel constituted higher proportion of saturated fatty acids followed by monounsaturated fatty acid and polyunsaturated fatty acids. Various fuel characteristics, namely, viscosity, density, free glycerin, triglycerides, diglycerides, monoglycerides, copper strip corrosion, flash point, cetane index, iodine value, calorific value, acid value, saponification value, phosphorous, sulfur, water, and ash contents were analyzed, and showed values within the specified limits of national and international biodiesel standards. Thus, considering the drying time, energy consumption, and lipid recovery with suitable fuel properties, the drum dryer could be recommended for drying the microalgal slurry for large-scale operation.

Bioconversion of chemically captured carbon dioxide into microalgal lipids, a potential source of biodiesel: An integrated technique

The rise of atmospheric carbon dioxide (CO2) concentration due to extensive anthropogenic activity besides rapid exhaustion of non-renewable energy sources demands evolution of clean and ecofriendly alternative fuel source. Recently, lipid rich microalgal biomass is being considerably researched for generation of biodiesel conversely, the expenses incurred on production of microalgal biomass is a substantial obstacle. Almost 80 % of the production cost is generated from the cultivation medium which majorly consists of carbon, nitrogen and phosphate. CO2 absorption by means of aqueous amine solvents is known to be a mature technology and could be integrated with microalgal cultivation unit for efficient utilization of the captured CO2. In this current investigation, piperazine (PZ) promoted aqueous blend of methyldiethanolamine (MDEA) having mass percentage ratio of (8/22 wt%) was used a CO2 capturing agent and then the captured CO2 was utilized as an inorganic carbon source for growing Chlorella sorokiniana BTA 9031 for biodiesel production. The CO2 absorption rate was governed by series of process variables namely, absorption temperature, initial CO2 concentration, solvent flow rate, gas flow rate and the optimal conditions were 315 K, 15 kPa, 3.6 × 10−4 m3 min−1 and 4 × 10−3 m3 min−1 respectively. The highest biomass strength of Chlorella sorokiniana BTA 9031 was observed to be 1.20 ± 0.028 g L−1. The fatty acid methyl esters (FAME) profile was determined after acid transesterification of the extracted microalgal lipids. It was observed to contain fatty acids suitable for biodiesel production.

Palm oil in diets for Nile tilapia (Oreochromis niloticus) post-larvae

The objectives of this research were to evaluate the effects of the substitution of soybean oil by palm oil in the diet of Nile tilapia (Oreochromis niloticus) post-larvae, to observe the performance and attractiveness of the feed, and to evaluate the fatty acid methyl esters profile of palm oil. Four hundred Nile tilapias were used after hatching (seven days old), distributed in 20 fiberglass tanks of 20 L each. The experiment was carried out in a completely randomized design with five treatments and four replicates. The treatments consisted of different levels of inclusion of palm oil, which were: 0.0, 1.5, 3.0, 4.5 and 6.0 %. The concentration of monounsaturated and saturated fatty acids in palm oil was measured, resulting in high amounts of palmitic, oleic and linoleic fatty acids. Significant differences were observed for the variables final weight, total length, weight gain, specific growth rate and condition factor. No significant differences were observed for palatability of the diets. It is concluded that the inclusion of 3% or more palm oil in substitution of soybean oil during the masculinization stage of tilapia larvae contributes to the improvement of productive parameters.

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.

Algal Biomass Harvesting Using Low-Grade Waste Heat: Investigation of Dewatering Algal Suspension by Evaporation

Abstract This study investigated the feasibility of harvesting algae biomass using an original and novel method that uses low-grade waste heat with an integrated heat exchanger, evaporation tank, and reservoir system. Several experiments were conducted. The experimental results showed good agreement with theoretical results estimated with a stagnant-film model. As the inlet gas temperature increased from 175 to 245 °C, the evaporation rate increased by 100%, while an 85% increase was achieved as the air speed increased from 0 to 3.5 m/s. It was also observed that the evaporation rate slightly decreased when doubling the volume of the reservoir while it is independent of the duration of experiment. The amount of lipid extracted from centrifuged algae was slightly higher than algae harvested by evaporation. However, the total amount of fatty acid methyl esters (FAMEs) was significantly higher, by 24%, for the algae harvested by evaporation compared with centrifugation. The FAMEs profiles were the same for both methods and about 98% of FAMEs were C-16 and C-18 carbon chains which are the main components of the algal biodiesel. The method has a potential to be developed into a cost-effective and energy efficient algal biomass dewatering method. It uses low-grade waste heat, which is cheap and readily available, and has simple and inexpensive structure. It was also demonstrated that modifying the proposed system, by adding a second heat exchanger in series, improved the water evaporation rate by 58–121%, depending on the operating conditions.

Aspergillus caespitosus ASEF14, an oleaginous fungus as a potential candidate for biodiesel production using sago processing wastewater (SWW)

BackgroundOleaginous microorganisms are sustainable alternatives for the production of biodiesel. Among them, oleaginous fungi are known for their rapid growth, short life cycles, no light requirement, easy scalability, and the ability to grow in cheap organic resources. Among all the sources used for biodiesel production, industrial wastewater streams have been least explored. We used oleaginous fungi to decontaminate sago processing wastewater and produce biodiesel.ResultsAmong the 15 isolates screened for lipid production and starch utilization using the Nile red staining assay and amylase plate screening, three isolates accumulated > 20% (w/w) of their dry cell mass as lipids. The isolate ASEF14 exhibited the highest lipid accumulation (> 40%) and was identified as Aspergillus caespitosus based on the 28S rRNA gene sequencing. The maximum lipid content of 54.4% in synthetic medium (SM) and 37.2% in sago processing wastewater (SWW) was produced by the strain. The Fourier-transform infrared (FTIR) spectroscopy of the fungal oil revealed the presence of functional peaks corresponding to major lipids. Principal component analysis (PCA) of the FTIR data revealed major changes in the fatty acid composition during the transition from the growth phase (Days 1–3) to the lipid accumulation phase (Days 4–7). The fatty acid methyl esters (FAME) analysis of fungal oil from SWW contained 43.82% and 9.62% of saturated and monounsaturated fatty acids, respectively. The composition and percentage of individual FAME derived from SWW were different from SM, indicating the effect of nutrient and fermentation time. The fuel attributes of the SM- and SWW-grown fungal biodiesel (kinematic viscosity, iodine value, cetane number, cloud and pour point, linolenic acid content, FA > 4 double bonds) met international (ASTM D6751, EN 14214) and national (IS 15607) biodiesel standards. In addition to biodiesel production, the strain removed various contaminants such as total solids (TS), total suspended solids (TSS), total dissolved solids (TDS), dissolved oxygen (DO), chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen (TN), total phosphorus (TP), and cyanide up to 58.6%, 53.0%, 35.2%, 94.5%, 89.3%, 91.3%, 74.0%, 47.0%, and 53.84%, respectively, from SWW.ConclusionThese findings suggested that A. caespitosus ASEF14 is a potential candidate with high lipid accumulating ability (37.27%), capable of using SWW as the primary growth medium. The medium and incubation time alter the FAME profile of this fungus. The physical properties of fungal oil were in accordance with the biodiesel standards. Moreover, it decontaminated SWW by reducing several polluting nutrients and toxicants. The fungal biodiesel produced by this cost-effective method could serve as an alternate path to meet global energy demand.

Vertical distribution and effect of historical residual organochlorine pesticides on microbial community structure in sediment cores from an abandoned oxidation pond after dredging for 15 years.

The vertical distribution pattern of 19 organochlorine pesticides (OCPs), together with microbial ester-linked fatty acid methyl ester (EL-FAME) profiles were investigated in sediments from an abandoned oxidation pond of Ya-Er lake, China, which had been heavily polluted by hexachlorocyclohexanes (HCHs) and chlorobenzenes in 1980s. Subsurface sediment samples were taken from five sediment cores along the transect running from the lakeshore (0.5~2.7 m in depth) to lakebed (0.1~0.4 m). The total OCP concentration ranged from 29.8 to 941.8 ng g-1 dw. Hexachlorobenzene (HCB), HCHs, and dichlorodiphenyl-trichloroethanes (DDTs) were the three dominant OCP classes, accounting for 26.5-97.4%, 1.8-33.2%, and 0.4-15.5% of the total OCP concentration, respectively. Hot spots of HCB, HCHs, and DDTs were detected at 0.9~2.7 m deep layers of the lakeshore, where was oncethe maindredged sediment backfill site for in-situ remediation of the oxidation pond in 2002-2004. HCHs and HCBstill showed high potential ecological risks. The sources of OCPs were identified and quantified using principal component analysis with absolute principal component scores-multiple linear regression model. The firstthree major sources were persistent residues, recent agricultural input, and historical industrial input, contributing on average 28.2%, 17.9%, and 17.1% of total OCPs, respectively. Redundancy analysis of microbial EL-FAME profiles and nine dominant OCPs revealed that the spatial variation in microbial community structure was significantly corresponded with the OCP composition. This is the first study highlighting the concern on historical industrial inputs of OCPs in subsurface sediments of the lakeshore disposal zone. The findings could help to distinguish the artificial backfill sediments from undisturbed polluted sediments for optimization of further dredging plans.

The Fatty Acid Methyl Ester (FAME) profile of Phytophthora agathidicida and its potential use as diagnostic tool.

ABSTRACTPhytophthora diseases cause devastation to crops and native ecosystems worldwide. In New Zealand, Phytophthora agathidicida is threatening the survival of kauri, an endemic, culturally and ecologically important tree species. The current method for detecting P. agathidicida is a soil bating assay that is time-consuming and requires high levels of expertise to assess, thus limiting the analytical sample throughput. Here, we characterized the fatty acid methyl ester (FAME) profile of P. agathidicida. We also compared it with the FAME profile of P. cinnamomi and assessed the efficacy of FAME analysis as a diagnostic tool for detecting the pathogen in soil samples. In FAME analysis, the total fatty acid content is isolated from a sample and converted to FAMEs for analysis, a process that takes less than a day. Unique fatty acid acyl chains can serve as biomarkers for specific organisms. We detected 12 fatty acids in P. agathidicida, two of which (20:4ω6 and 20:5ω3) show promise as potential Phytophthora specific biomarkers. Collectively, these findings advance our fundamental understanding of P. agathidicida biology and provide a promising technique to increase the rate of sample processing and the speed of pathogen detection for P. agathidicida in soil.

The assessment of the engine performance and emissions of a diesel engine fueled by biodiesel produced using different types of catalyst

In the present study, the biodiesel was produced from waste cooking oil using two types of catalyst (homogeneous (Hom. Cat.) and heterogeneous (Het. Cat.)). The produced biodiesels were characterized to obtain their physicochemical properties and fatty acid methyl esters (FAMEs) profile. Then, they were blended with net diesel fuel at volume ratios of 10:90 (B10), 25:75 (B25), and 40:60 (B40) for using in the injection system of a 6-cylinder diesel engine operated at a constant speed of 1500 rpm to compare changes in the combustion (engine performance) and exhaust emissions of engine. The results showed that the catalyst type had an insignificant effect on the physical properties of produced biodiesel such as density, viscosity, flash, cloud and pour point, higher heating value, etc., whereas the compositions of FAME contents slightly changed. On the other hand, the total production duration was lower for the biodiesel produced by heterogeneous catalyst (21 h against 26 h), while the higher amount of energy consumed (2165 against 1650 Wh/L). Blending net diesel fuel with biodiesels slightly improved the engine performance and combustion behavior. The exhaust gas emissions were also showed an appropriate decrease in carbon monoxide (5–40%), unreacted hydrocarbon (40–75%), and smoke opacity (8–25%) emissions using biodiesel produced heterogeneous catalyst. The statistical analysis of results showed that blending the net diesel fuel with 34 vol% of biodiesel and operating the diesel engine at 40% of fuel load can lead to an appropriate engine performance along with a considerably reduction in the exhaust gas emissions.

Adaptation of phenol-degrading Pseudomonas putida KB3 to suboptimal growth condition: A focus on degradative rate, membrane properties and expression of xylE and cfaB genes

Detailed characterization of new Pseudomonas strains that degrade toxic pollutants is required and utterly necessary before their potential use in environmental microbiology and biotechnology applications. Therefore, phenol degradation by Pseudomonas putida KB3 under suboptimal temperatures, pH, and salinity was examined in this study. Parallelly, adaptive mechanisms of bacteria to stressful growth conditions concerning changes in cell membrane properties during phenol exposure as well as the expression level of genes encoding catechol 2,3-dioxygenase (xylE) and cyclopropane fatty acid synthase (cfaB) were determined. It was found that high salinity and the low temperature had the most significant effect on the growth of bacteria and the rate of phenol utilization. Degradation of phenol (300 mg L−1) proceeded 12-fold and seven-fold longer at 10 °C and 5% NaCl compared to the optimal conditions. The ability of bacteria to degrade phenol was coupled with a relatively high activity of catechol 2,3-dioxygenase. The only factor that inhibited enzyme activity by approximately 80% compared to the control sample was salinity. Fatty acid methyl ester (FAMEs) profiling, membrane permeability measurements, and hydrophobicity tests indicated severe alterations in bacteria membrane properties during phenol degradation in suboptimal growth conditions. The highest values of pH, salinity, and temperature led to a decrease in membrane permeability. FAME analysis showed fatty acid saturation indices and cyclopropane fatty acid participation at high temperature and salinity. Genetic data showed that suboptimal growth conditions primarily resulted in down-regulation of xylE and cfaB gene expression.

Synthesis, characterization and application of intracellular Ag/AgCl nanohybrids biosynthesized in Scenedesmus sp. as neutral lipid inducer and antibacterial agent

The current research focuses on the Intracellular biosynthesis of Ag/AgCl nanohybrids in microalgae, Scenedesmus sp. The effect of biosynthesis process on growth and lipid profile of cells is key element of this study. Ag/AgCl nanohybrids synthesized intracellularly were characterized by UV–Vis spectrophotometer, Powder X-Ray Diffraction (P-XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM). 10–20 nm and 10–50 nm sized spherical shaped nanoparticles of polycrystalline nature were grown using 0.5 and 1 mM of AgNO3 precursor, respectively and Scenedesmus sp. as reducing agent. Total lipid content of the cells treated with 0.5 mM and 1 mM AgNO3 was static and found to be 43.2 ± 0.01 μg/mL and 48.2 ± 0.02 μg/mL respectively at 120 h of Ag/AgCl nanoparticles biosynthesis. FAME (Fatty Acid Methyl Ester) profile was improved due to intracellular nanoparticles biosynthesis with maximum C16:0 (palmitic acid) (35.7%) in cells treated with 0.5 mM AgNO3 used for Ag/AgCl nanohybrids synthesis. Palmitic acid in cells exposed to 0.5 mM concentration of metallic precursor increased by 75.86%. Synthesized nanoparticles were tested on four bacterial strains to establish its antibacterial efficiency showing appropriate zone of inhibition at varying concentrations. Present study efficiently demonstrates the utility of microalgae integrating nanoparticles biosynthesis and lipid accumulation.

Impact of hydrogen peroxide on microalgae cultivated in varying salt-nitrate-phosphate conditions

Microalgal biomass has received a great deal of attention as renewable and environmental-friendly biofuel feedstock as a rebuttal to climate change, energy crisis, and global warming. To improve the commercial viability of algal biodiesel production, the rise in lipid accretion and the enrichment of algal fatty acid profile are of utmost importance. In this experiment, lipid content and fatty acid methyl ester profiling of the microalgal strain, Scenedesmus sp. is done to understand the intercalating effect of different media composition for its suitability in context to biodiesel production. Various nutrient combinations (sodium nitrate, NaNO3) and di-potassium hydrogen phosphate, (K2HPO4) were incorporated along with salinity (sodium chloride) exposure for first 48 h stage of algal cultivation, followed by oxidative stress via hydrogen peroxide (H2O2) for the second 24 h stage of cultivation. The results show that the presence of 100 mM NaCl, 35.29 mM NaNO3, and 5.74 mM K2HPO4 followed by the addition of 10 mM H2O2 (S100H10N35.29P5.74) to the algal growth media led to the accumulation of maximum total lipid content (226.49 ± 16.6 μg/mg). Another nutrient combination, S0H10N35.29P0, increased the saturated fatty acid composition (C16:0) to 31.7%. Principal component analysis (PCA) also demonstrated the combined effect of multiple nutrient components and their relative concentrations on the growth parameters and algal biochemical profile, such as biomass, chlorophyll, lipid, carbohydrate, alongwith fatty acid profiling. Hence, this study demonstrate the potential of Scenedesmus sp. in response to a multi-component stress environment that has influenced the fate of fatty acid methyl esters (FAME) composition and significantly improved the quality of algal biofuels produced over a short period.

Nordic cyanobacterial and algal lipids: Triacylglycerol accumulation, chemotaxonomy and bioindustrial potential.

The ability to capture and convert sunlight, water and nutrients into useful compounds make photosynthetic microbes ideal candidates for the bio-industrial factories of the future. However, the suitability of isolates from temperate regions to grow under Nordic conditions is questionable. In this work, we explore the chemotaxonomy of Nordic strains of cyanobacteria and one green alga and evaluate their potential as raw materials for the production of lipid-based bio-industrial compounds. Thin-layer chromatography was used to identify the presence of triacylglycerol, which were detected in the majority of strains. Fatty acid methyl ester profiles were analysed to determine the suitability of strains for the production of biodiesel or the production of polyunsaturated fatty acids for the nutraceutical industry. The Nordic Synechococcus strains were unique in demonstrating fatty acid profiles comprised mostly C14:0, C16:0 and C16:1 and lacking polyunsaturated fatty acids. These properties translated to superior predicted biodiesel qualities, including cetane number, cold filter plugging point and oxidative stability compared to the other evaluated strains. Polyunsaturated fatty acids were detected at high levels (38-53%), with Calothrix sp. 336/3 being abundant in two essential fatty acids, linoleic and alpha-linolenic acid (21 and 17%, respectively). Gamma-linoleic acid was the predominant polyunsaturated fatty acid for the remaining strains (13-21%). In addition to assessing the potential of Nordic strains for bio-industrial production, this work also discusses issues such as taxonomy and predictive modelling, which can affect the identification of prospective high-performing strains.

Evaluation of high salinity adaptation for lipid bio-accumulation in the green microalga Chlorella vulgaris.

Aiming at the reutilizing wastewater for algal growth and biomass production, a saline water rejected from reverse osmosis (RO) facility (salinity 67.59 g L−1) was used to cultivate the pre-adapted green microalga Chlorella vulgaris. The inoculum was prepared by growing cells in modified BG-11 medium, and adaptation was performed by applying a gradual increase in salinity (56.0 g L−1 NaCl and 125 ppm FeSO4·7H2O) to the culture in 200 L photobioreactor. Experiments using the adapted alga were performed using original-rejected water (ORW) and treated rejected water (TRW) comparing with the recommended growth medium (BG-11). The initial salinity of ORW was chemically reduced to 39.1 g L−1 to obtain TRW. Vertical photobioreactors (15 L) was used for indoor growth experiments. Growth in BG-11 resulted in 1.23 g L−1, while the next adaptation growth reached 2.14 g L−1 of dry biomass. The dry weights of re-cultivated Chlorella after adaptation were 1.49 and 2.19 g L−1 from ORW and TRW; respectively. The cellular oil content was only 12% when cells grown under control conditions verses to 14.3 and 15.42% with original and treated water, respectively. Induction of stress affected the fatty acid methyl esters (FAMEs) profile and the properties of the resulting biodiesel. The present results indicated that induction of stress by high salinity improves the quality of FAMEs that can be used as a promising biodiesel fuel.

Potential Assessment of Oleaginous Fungi for Sustainable Biodiesel Production: Screening, Identification and Lipid Production Optimization

The present work, aiming to exploit oleaginous fungi for biodiesel production. Ten fungal strains were isolated from two petroleum polluted soil samples and screened for their abilities to accumulate lipid. Lipid rich three species viz, Aspergillus terreus, Aspergillus niger and Aspergillus flavus were found to be the highest lipid producers. Potential isolates were identified at the species level by morphological (macroscopic and microscopic) examination and molecularly confirmed by using 18S rRNA gene sequencing. Improvement of lipid accumulation was performed by optimization of various parameters of culture conditions. The results reported clearly that the suitable medium for high lipid production (38.33%) by Aspergillus terreus as the most potent lipid producer, was composed of 50 g/L sucrose, 0.5 g/L ammonium nitrate with initial pH 6.0, after seven days of incubation in a static condition. The three promising lipid isolates have been selected for fatty acids analysis by gas chromatograph (GC) after transesterification. Fatty acid methyl esters (FAME) profile indicated the presence of higher saturated fatty acid fractions compared to polyunsaturated fatty acids. The total concentration of fatty acids was 107.98, 38.29, and 37.48 mg/100g of lipid accumulated by A. terreus, A. niger and A. flavus, respectively. Gas chromatographic analysis of A. terreus lipid indicated that oleic acid (C18:1, 18.51%) was the most abundant fatty acid, followed by stearic acid (C18:0, 15.91%) and Myristic acid (C14:0, 14.64%), respectively. Therefore, fatty acid profile of A. terreus has confirmed its potentiality as feedstock for producing lipid for biodiesel manufacturing.

The impact of abiotic factors on the growth and lipid accumulation of some green microalgae for sustainable biodiesel production.

Three species of freshwater planktonic green microalgae: Ankistrodesmus braunii, Ankistrodesmus falcatus, and Scenedesmus incrassatulus, were isolated from the Nile water in Upper Egypt. These microalgae were exposed to nutritional (nitrogen, phosphorus, and iron) limitations and salinity stress to study their effects on the algal growth and to elevate the lipid content within their cells. The results indicated that exposure to these conditions had a significant impact on the algal growth. The lipid content of the studied algae increased as a result of the salinity stress. The highest lipid content was recorded in A. braunii culture treated with 50 mM NaCl (34.4% of dry weight) and S. incrassatulus cultures treated with 100 mM NaCl (37.7% of dry weight) on the 6th day of cultivation, while the culture of A. falcatus treated with 100 mM NaCl recorded the maximum lipid content (53% of dry weight) on the 10th day of the experiment. The biodiesel quality parameters of the fatty acid methyl ester profile of S. incrassatulus appeared to be in agreement with the international criteria. S. incrassatulus could be regarded as a quite promising feedstock for the biodiesel production.