Fatty Acid Methyl Esters Biodiesel Research Articles

Saccharomyces cerevisiae cellular engineering for the production of FAME biodiesel

The unsustainable and widespread utilization of fossil fuels continues to drive the rapid depletion of global supplies. Biodiesel has emerged as one of the most promising alternatives to conventional diesel, leading to growing research interest in its production. Microbes can facilitate the de novo synthesis of a type of biodiesel in the form of fatty acid methyl esters (FAMEs). In this study, Saccharomyces cerevisiae metabolic activity was engineered to facilitate enhanced FAME production. Initially, free fatty acid concentrations were increased by deleting two acetyl-CoA synthetase genes (FAA1, FAA4) and an acyl-CoA oxidase gene (POX1). Intracellular S-adenosylmethionine (SAM) levels were then enhanced via the deletion of an adenosine kinase gene (ADO1) and the overexpression of a SAM synthetase gene (SAM2). Lastly, the S. cerevisiae strain overproducing free fatty acids and SAM were manipulated to express a plasmid encoding the Drosophila melanogaster Juvenile Hormone Acid O-Methyltransferase (DmJHAMT). Using this combination of engineering approaches, a FAME concentration of 5.79 ± 0.56 mg/L was achieved using these cells in the context of shaking flask fermentation. To the best of our knowledge, this is the first detailed study of FAME production in S. cerevisiae. These results will provide a valuable basis for future efforts to engineer S. cerevisiae strains for highly efficient production of biodiesel.

Catalytic Upgrading of Biodiesel by Partial Hydrogenation of Its FAME Composition: A Systematic Review

Biodiesel is one of the most popular biofuels as it is a promising substitute for conventional diesel fuel, but for now, it cannot be used as a stand-alone fuel due to its low oxidative stability. For this reason, there have been efforts to upgrade biodiesel in the last few years through the partial hydrogenation of its fatty acid methyl esters (FAMEs). This procedure succeeds in resolving the problem of low oxidative stability, but in some cases, a new issue arises as non-selective hydrogenation deteriorates the fuel’s cold flow properties, which are crucial for vehicle’s operation without damaging the vehicle’s engine. More specifically, the problem of deteriorated cold flow properties is caused by the formation of trans-monounsaturated and fully saturated FAMEs during the hydrogenation reaction. Hydrogenated biodiesels are preferred to contain more cis-monounsaturated FAMEs because these are considered to have the best combination of high oxidative stability and good cold flow properties. As a result, various systems and methods have been tested to achieve selective partial hydrogenation of biodiesel FAMEs. In this review article, the catalytic systems and processes that stood out in various research studies are presented, and the factors that lead to the best possible outcome are investigated and discussed.

Development of a fast GC-response factor method to quantify total FAMEs in biodiesel from various fatty acid sources

Biodiesel is a renewable energy source that can be employed as an alternative fuel to fossil diesel. Monitoring samples in terms of fatty acid methyl esters (FAMEs) content using gas chromatography (GC) is a useful way to evaluate the quality of biodiesel produced. Fast GC can be used to reduce the time of analysis and consequently the costs, even though the equipment required for this may be expensive. Therefore, we developed and validated a Fast GC-response factor (Fast-GCRF) methodology using a low-priced nonpolar column, flame ionization detection (FID) and a standard chromatograph usually destined for conventional GC separations. The method was validated and applied to the quantification of FAMEs produced from various raw materials (soybean, cottonseed, canola, coconut, palm, sesame, sunflower, castor, corn, macauba, almond, peanut, chia seeds, residual frying oils, and chicken fat), being both selective and robust even when subjected to changes in sample preparation. The Fast GCRF method presented respective maximum relative standard deviation (RSD) values for instrumental precision, repeatability, and intermediate precision of 2.3 %, 3.6 %, and 2.8 %. When compared to conventional GC methodologies, accurate results with high degrees of agreement were obtained using the Fast-GCRF method, within an at least four times shorter analysis time.

Biodiesel exhaust particle airway toxicity and the role of polycyclic aromatic hydrocarbons

Renewable alternatives to fossil diesel (FD) including fatty acid methyl ester (FAME) biodiesel have become more prevalent. However, toxicity of exhaust material from their combustion, relative to the fuels they are displacing has not been fully characterised. This study was carried out to examine particle toxicity within the lung epithelium and the role for polycyclic aromatic hydrocarbons (PAHs). Exhaust particles from a 20% (v/v) blend of FAME biodiesel had little impact on primary airway epithelial toxicity compared to FD derived particles but did result in an altered profile of PAHs, including an increase in particle bound carcinogenic B[a]P. Higher blends of biodiesel had significantly increased levels of more carcinogenic PAHs, which was associated with a higher level of stress response gene expression including CYP1A1, NQO1 and IL1B. Removal of semi-volatile material from particulates abolished effects on airway cells. Particle size difference and toxic metals were discounted as causative for biological effects. Finally, combustion of a single component fuel (Methyl decanoate) containing the methyl ester molecular structure found in FAME mixtures, also produced more carcinogenic PAHs at the higher fuel blend levels. These results indicate the use of FAME biodiesel at higher blends may be associated with an increased particle associated carcinogenic and toxicity risk.

Synthesized heterogeneous nano‐catalyst from cow teeth for fatty acid methyl esters production through transesterification of waste vegetable frying oil and methanol: Characterization and optimization studies

AbstractUsing readily available biomass, it is possible to produce fatty acid methyl esters (FAME) at a low cost. This study focused on the transesterification process of waste frying vegetable oil to generate FAME (biodiesel) using a cost‐effective heterogeneous nano‐catalyst synthesized from waste cow teeth (CT). The cow teeth nano‐catalyst (CTNC) was synthesized via a three‐step method of calcination, hydration‐dehydration, and re‐calcination. The synthesized CTNC samples were characterized. The Box–Behnken design of response surface methodology (RSM) was used to obtain the optimal operating conditions that maximize the FAME yield (Y 1 ) and the effects of the transesterification process conditions on FAME production. The results revealed that CTNC is of microporous structure with higher crystallinity. It consists of hydroxyapatite, beta‐tricalcium phosphate, and calcium oxide, having a mean particle size of 43.96 nm, a specific surface area of 124.77 m 2 /g, and a pore volume of 0.303 cm 3 /g. The process conditions that significantly influenced the EWFVOME yield were the CTNC loading, reaction time, and MTOR. A maximum of 98.70% (Y 1 ) was obtained at the optimum transesterification process variables of reaction time (2 h), MTOR (12:1), and CTNC loading (3.75 wt%). The biodiesel fuel properties were found to be within the acceptable values of ASTM D6751 and EN 14214 fuel standards.

Reactive Extraction for Fatty Acid Methyl Ester Production from Castor Seeds Using a Heterogeneous Base Catalyst: Process Parameter Optimization and Characterization

Fatty acid methyl ester (FAME) from oil seeds is conventionally produced via a two/three-process-step method: extraction of oil and subsequent esterification/transesterification to fatty FAME (biodiesel). However, in the present study, we investigated the production of castor kernel oil (CKO) FAME by reactive extraction for extraction and transesterification in a single process using a heterogeneous catalyst. The content of oil that can be extracted was checked by investigating several nonreactive extraction parameters such as solvent type (polar, nonpolar, and mixture), the solvent to kernel ratio, and extraction time. Maximum oil was extracted using methanol as a solvent with a methanol-to-seed ratio of 6.25:1 for 6 h extraction time. The viscosity of CKO obtained by nonreactive extraction was reduced from 288.83 to 19.04 mm2/s by reactive extraction using a 4.09 wt % catalyst concentration (BaO) and a 330.9:1 methanol-to-oil molar ratio for 6 h reaction time at 64 °C. Reactive extraction for transesterification of CKO was performed using BaO, CaO, and ZnO heterogeneous catalysts. BaO results in the increased yield of CKO FAME compared to other catalysts. Central composite design (CCD) using the response surface methodology (RSM) was implemented to design the experimental matrix, process parameter optimization, maximize the yield of CKO FAME, and investigate interaction effects of parameters such as reactive extraction temperature (55-65 °C), catalyst concentration (3-5 wt %), and methanol-to-oil molar ratio (175:1-350:1) on the yield of CKO FAME. A second-order model equation with a p-value < 0.05 and an R 2 value near 1.0 was obtained to predict the yield using the input parameters. The maximum yield CKO FAME of 96.13 wt % with 94.4% purity of produced CKO FAME was obtained at a catalyst concentration of 4.09 wt % and a methanol-to-oil molar ratio of 330.9:1 for 6 h with a reaction temperature of 64 °C. Therefore, a comparable conversion of castor seed oil triglyceride (96.13 wt %) was obtained in a single step directly from castor seeds. Furthermore, the rheological behavior investigation of castor kernel oil and castor methyl ester revealed that the dynamic viscosity of both samples was found to be dependent on triglyceride content and temperature.

Optimization of heterogeneous Catalyst-assisted fatty acid methyl esters biodiesel production from Soybean oil with different Machine learning methods

There is a growing attention to the bio and renewable energies due to fast depletion of fossil fuels as well as the global warming problem. Here, we developed a modeling and simulation method by means of artificial intelligence (AI) for prediction of the bioenergy production from vegetable bean oil. AI methods are well known for prediction of complex and nonlinear process. Three distinct Adaptive Boosted models including Huber regression, LASSO, and Support Vector Regression (SVR) as well as artificial neural network (ANN) were applied in this study to predict actual yield of Fatty acid methyl esters (FAME) production. All boosted utilizing the Adaptive boosting algorithm. The important influencing parameters on the biodiesel production such as the catalyst loading (CAO/Ag, wt%) and methanol to oil (Soybean oil) molar ratio were selected as the input variables of models while the yield of FAME production was selected as output. Model hyper-parameters were tuned to maintain generality while improving prediction accuracy. The models were evaluated using three distinct metrics Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and R2. Error rates of 8.16780E-01, 4.43895E-01, 2.06692E + 00, and 3.92713 E-01 were obtained with the MAE metric for boosted Huber, SVR, LASSO and ANN models. On the other hand, the RMSE error of these models were about 1.092E-02, 1.015E-02, 2.669E-02, and 1.01174E-02, respectively. Finally, the R-square score were calculated for boosted Huber, boosted SVR, and boosted LASSO as 0.976, 0.990, 0.872, and 0.99702, respectively. Therefore, it can be concluded that although the boosted SVR and ANN models were better models for prediction of process efficiency in terms of error, but all algorithms had high accuracy. The optimum yield of 83.77% and 81.60% for biodiesel production were observed at optimum operating values from boosted SVR and ANN models, respectively.

Compatibility of Engine Oil Viscosity Improver and Biodiesel Fatty Acid Methyl Ester

The present work focused on the compatibility of a popular engine oil viscosity improver polymethacrylate (PMA) and a biodiesel fatty acid methyl ester methyl oleate (MO). Thermal oxidation operations of blends of PMA, MO and a mineral base oil were performed for evaluating the interactions between PMA and MO. The viscosity and viscosity index of fresh and oxidized blends were determined and calculated. Thereafter the chemical compositions of oxidized blends were characterized by a gas chromatography coupled to a mass spectrometer. Results showed that viscosities of the blends increased after oxidation, and the increases in viscosity after oxidation for blends containing MO were greater than those for blends without MO. Furthermore, PMA was substantially efficient in improving viscosity index of both fresh and oxidized blends with and without MO, although viscosity index of blends slightly declined with increasing concentrations of MO in a blend. Finally, chemical species of methacrylates were generated in the oxidation processes of blends, despite whether or not there was MO in the blends. The present results preliminarily demonstrated that direct chemical interactions between PMA and MO were unobvious, and confirmed that PMA was well compatible with MO in viscosity index improvement.

Qualitative and quantitative analysis of the influence of biodiesel fatty acid methyl esters on iodine value.

Iodine value (IV) is an indicator to evaluate the degree of unsaturation (DU) of biodiesel. It reflects the biodiesel degradation and oxidation stability (OS) and also has an effect on viscosity, low-temperature flow properties (LTFP), and the combustion performance. To construct a theoretical system for the simultaneous optimization of LTFP and OS of biodiesel using IV, 52 measured experimental data are used to investigate the qualitative and quantitative relationship between IV and biodiesel composition. The relationships between biodiesel physicochemical properties and IV are investigated in this work. The qualitative analysis shows that the poly-unsaturated fatty acid methyl esters (FAMEs) contribute to an increase in IV, whereas saturated and mono-unsaturated FAMEs decrease IV. Multiple linear regression (MLR) and artificial neural network (ANN) are used to estimate IV from FAMEs. The correlation coefficient, root mean squared error (RMSE), and mean absolute percentage error (MAPE) are respectively 0.976, 2.45, and 1.76% for the MLR model and 0.983, 2.14, and 1.57% for the back propagation neural network (BPNN) model; these values indicate the high accuracy of these methods. The performances of the proposed models were compared with three existing IV prediction models and validated by another databank. The results indicate that the application of the developed BPNN model is better and more comprehensive. Additionally, a preliminary conclusion is that biodiesel with a low percentage of both long-chain saturated and poly-unsaturated FAMEs can have solidifying point (SP) and OS in the proper range. Biodiesel with a low IV is generally more combustible and efficient.

Palm Oil-based Fatty Acid Methyl Ester (FAME) Biodiesel to Meet High Blending Rates in Malaysia

Palm oil methyl ester (PME) is a form of fatty acid methyl ester (FAME) which in principle is biodiesel. Malaysia could greatly leverage the abundance of PME sources given its status as a palm oil-producing country. In this paper, palm oil is evaluated for its potential as a biofuel feedstock and its derivatives’ vast use in the domestic market but limited use in other regions. In order to create a growth market of PME, Malaysia has introduced an increase of PME blend component in its nation’s biodiesel use for transport and industrial sectors. A phased increase from 5% to the latest of 20% PME blend in biodiesel certainly has the potential to reduce greenhouse gas emissions, while creating a boost to the local market. However, the government must be careful in managing subsidies of conventional petroleum-based diesel fuel, as this would have an eventual effect on the supply chain of biodiesel in Malaysia. There are limited studies on diesel fuel physicochemical characteristics that are used as base-stock for the biodiesel blend and whether it could be manipulated to maximise yield while maintaining conformance to mandated fuel standards. Multiple relevant research papers were studied of its relevance to PME use as biodiesel FAME to meet high blending rates in Malaysia.

Effects of unsaturated fatty acid methyl esters on the oxidation stability of biodiesel determined by gas chromatography-mass spectrometry and information entropy methods

To explore the trend of fatty acid methyl esters (FAMEs) during the oxidation process of biodiesel, this study uses gas chromatography - mass spectrometry (GC-MS) combined with information entropy theory to propose a new method to analyze the effect of FAMEs on the stability of biodiesel (especially with different amounts of unsaturated FAMEs). The induction periods of the main FAMEs in biodiesel were determined by the Rancimat method. The results showed that the longest induction period of methyl stearate was 248 h, while the induction of methyl linoleate was only 0.12 h. Accelerated oxidation of biodiesel, using GC-MS analysis showed that the oxidation trends of FAMEs was different. The oxidation rate of methyl linoleate was the fastest. A mathematical equation was proposed to calculate the trend of FAMEs. The results showed that during the 5 h accelerated an oxidation process, the content of methyl linoleate decreased from 28.35% to 2.10%, while the content of methyl oleate decreased by 18.21%. Using information entropy, the weighting coefficients of FAMEs in the oxidation process of biodiesel were calculated. The weighting coefficient of methyl linoleate was as high as 0.6797. Methyl linoleate was the main reason why biodiesel was easily oxidized.

Study on the mechanism of auto-oxidation of Jatropha biodiesel and the oxidative cleavage of C[sbnd]C bond

Jatropha biodiesel was obtained according to the continuous preparation process which included vapor esterification - transesterification - methanol steam distillation. Accelerated oxidation of small Jatropha biodiesel was obtained by the Rancimat method. GC–MS and liquid phase micro-extraction were used to study and analyze the components in the oxidation process of Jatropha curcas biodiesel. The electronic effects of the related reactants and products were calculated by density functional theory, followed by the deduction of the related chemical reaction paths. Experimental investigation shows that methyl linoleate is the main factor affecting the oxidation stability of the Jatropha biodiesel. The main volatile products at the initial stages of the oxidation of methyl linoleate are hexanal, methyl octanoate, styrene, and 2-heptenal. The cis/trans-3-octyl-oxiranyl octanoic acid methyl ester (18.03% yield) is produced by the reaction of peroxy acid and methyl oleate during the oxidation of methyl oleate. The hydrogen extraction reaction is difficult to occur, and the oxidation reaction energy barrier is relatively high due to the relatively large bond energy of the CH bond in the methyl stearate molecule. In this manuscript, the auto-oxidation mechanism of the biodiesel fatty acid methyl esters at the initial stage of oxidation, the path of oxidative cleavage of the CC bond of Jatropha biodiesel and the formation process of ethylene oxide structure are obtained through DFT calculation and analysis of the oxidation products.

Soil acidification and impacts over microbial indicators during attenuation of soybean biodiesel (B100) as compared to a diesel-biodiesel blend (B8)

Biodiesel presents a higher degradability than petroleum hydrocarbons in soils. Since microorganisms dominate biodegradation processes, impacts on soil microbiota provide information regarding the course of fuel attenuation. We aimed to evaluate the effects of biodiesel (B100) and a diesel–biodiesel blend (B8) on soil microbial indicators. In microcosms, an oxisol was spiked with B100 (5% and 10%, w w-1 dry soil) or B8 (5% and 10%, w w-1 dry soil). In addition to microbial parameters, phytotoxicity, pH, and fuel attenuation were assessed during 90 days. Spiked soils exhibited increased cumulative respiration than non-contaminated controls; however, it was lower with B100 (140–204%) than with B8 (347–420%). Initial pH (6.0) slightly diminished with B8 after 90 days (~5.7), but decreased to ~3.9 after 30 days with B100. Heterotrophic and B8-degrading bacteria were 1.6–2.4 and 1.5–2.5 Log higher with B8 as compared to controls; conversely, heterotrophic and B100-degrading populations were reduced by B100 (3.5–4.5 and 4.7–6.8 Log lower than controls). B100 resulted in more prominent negative impacts on microbial biomass, metabolic quotient and soil enzyme activities. Phytotoxicity towards cucumber seeds tended to be mitigated in B8-5% soil, whereas the opposite has been observed with B100. Biodiesel fatty acid methyl esters (FAME) were completely (or highly) attenuated in B8 microcosms; nonetheless, in B100 soils, partial attenuation occurred only for unsaturated FAME. These findings are particularly discussed considering the prominent acidification in B100-spiked soils. In addition to B8, the results indicate that heavy soil contaminations with biodiesel pose significant environmental hazards.

Assessment of the Impact of Trace Elements in FAME Biodiesel on Diesel Oxidation Catalyst Activity after Full Lifetime of Operation in A Heavy-Duty Truck

Fatty acid methyl ester (FAME) biodiesel contains some trace amounts of Na, K, P, Ca, and Mg. Our objective was to investigate whether the presence of such elements can poison a diesel oxidation catalyst that has been used for an entire regulatory lifetime in a heavy-duty truck fueled by FAME biodiesel. The investigated vehicle-aged catalyst contained high loadings of S, P, and Na, as well as a visible layer of soot. Activity in the NO oxidation reaction was severely decreased compared to a fresh catalyst of the same type, while the CO and C3H6 oxidation reactions were less affected. Subsequent selective trace element removal procedures, followed by activity tests, were used to decouple the effect of different poisons. Sintering was observed to be the main cause of catalyst deactivation. Of the trace elements present on the catalyst, P had the greatest effect on catalyst activity, while the other trace elements had little effect.

Experimental investigation of effect of biodiesel fatty acid methyl ester on performance of engine oil dispersant additive

In the present work, blends of methyl oleate (MO), polyisobutylene-bis-succinimide (PIBSI) and a mineral lubricant base oil were oxidized and some of their physicochemical properties were evaluated to understand the effects of biodiesel fatty acid methyl esters on the performance of the engine oil dispersant additive PIBSI. The oxidation experimentations of blends were conducted under elevated temperatures. Thereafter, the viscosity and acidity of fresh and oxidized blends were determined. The dispersancy, thermal stability and chemical species of oxidized samples were tested and analyzed by the blotter spot method, a TGA, and a GC/MS, respectively. Results showed that the viscosity and acidity of blends containing MO increased significantly after oxidation. The dispersing ability of PIBSI was markedly impaired by only a small amount of MO in a blend. In addition, the thermal characteristics of blends were altered by MO. Many varieties of oxygenated chemicals in the oxidized blend containing MO were detected. The negative impact of MO on performances of PIBSI was attributed to the accelerated oxidation caused by MO, and to the chemical interactions between MO and PIBSI. The present results demonstrated that PIBSI was incompatible with MO.

Composition of Reduced Mechanisms for Ignition of Biodiesel Surrogates

Chemical kinetics mechanisms describing Fatty Acid Methyl Ester (FAME) biofuel combustion are quite extensive and cannot be implemented in Computational Fluid Dynamics simulations of real engine systems. Using the reduction methodology Ant Colony Reduction (ACR), skeletal reduction followed by optimization has been performed for the C-11 FAME biodiesel components methyl decanoate (MD), methyl 5-decenoate (MDe5), and methyl 9-decenoate (MDe9), and for the alkane n-decane. The aim of the present study was to produce small reduced mechanisms accurately describing ignition of the fuels over a wide range of conditions, and in addition to compare the size and composition of reduced mechanisms constructed from two parent mechanisms of different complexity. Reduction targets were ignition delay times over a wide range of equivalence ratios and pressures, for separate temperature ranges of 600–1100 K (LT) and 1100–1500 K (HT). One of the complex mechanisms was constructed to be simplified by a lumping approach and this one included MD and was also used to perform reduction for the alkane n-decane. The most detailed parent mechanism was used to create reduced mechanisms for all the three methyl esters. The lumped complex mechanisms resulted in more compact reduced mechanisms, 157 reactions for LT of MD, compared to 810 reactions for the more detailed mechanism. MD required the largest fuel breakdown subsets while the unsaturated methyl esters could be described by smaller subsets. All mechanisms had similar subsets for the smallest hydrocarbons and H/O chemistry, independent of the fuel and the choice of parent mechanism. The ACR approach for mechanism reduction created reduced mechanisms with high accuracy for all conditions included in the present study.

Biorefining of Waste Coffee Grounds: Turning an Environmental Problem into an Opportunity

The work presented herein proposes to turn the growing environmental threat posed by coffee waste disposal into an opportunity by proposing a number of valorization routes of waste coffee grounds (WCG) through biorefining. In this process, various steps were studied: drying of WCG on small and medium scales, coffee oil extraction from small to large scale, conversion of coffee oil into biodiesel, and suggestions of designs for the recycling of de-oiled WCG into briquettes. Drying was found to be best performed using an elevated hot air tunnel rather an electric pan or a motorized stirrer. Solvent extraction of coffee oil from dried WCG on a 2000 g scale afforded a 9.2 wt% yield and a solvent recovery yield of 94 vol%. This oil was successfully converted into fatty acid methyl esters biodiesel with a 58% yield. Several original and cost-effective designs were tested, some of which being readily reproducible in most laboratory settings.

Co-production of biodiesel and bioethanol using psychrophilic microalga Chlamydomonas sp. KNM0029C isolated from Arctic sea ice

BackgroundBiofuels, generated using microalgae as sustainable energy, have received a lot of attention. Microalgae can be cultivated at low cost with CO2 and solar energy without competition from edible crops. Psychrophilic microalgae can be a suitable feedstock to produce biofuels without the environmental constraints of low temperatures, because they can grow below 10 °C. However, there is a lack of efficient strategies using psychrophilic microalgae to produce biodiesel and bioethanol. Therefore, the current study aimed to optimize the production of biodiesel and bioethanol from Arctic Chlamydomonas sp. KNM0029C at low temperatures.ResultsAfter incubation in a 20-L photobioreactor, fatty acid methyl ester (FAME) was extracted using modified FAME extraction methods, producing a maximum yield of 0.16-g FAME/g KNM0029C. Residual biomass was pretreated for bioethanol production, and the yields from different methods were compared. The highest bioethanol yield (0.22-g/g residual biomass) was obtained by pretreatment with enzyme (amyloglucosidase) after sonication. Approximately 300-mg biofuel was obtained, including 156-mg FAME biodiesel and 144-mg bioethanol per g dried cells, representing the highest recorded yield from psychrophilic microalgae.ConclusionsThis is the first to attempt at utilizing biomass from psychrophilic Arctic microalga Chlamydomonas sp. KNM0029C for the co-production of bioethanol and biodiesel, and it yielded the highest values among reported studies using psychrophilic organisms. These results can be used as a source for the efficient biofuel production using polar microalgae.

Nanoparticle-mediated Impact on Growth and Fatty Acid Methyl Ester Composition in the Cyanobacterium Fremyella diplosiphon.

Insufficient light supply is a major limitation in cultivation of cyanobacteria for scaled up biofuel production and other biotechnological applications, which has driven interest in nanoparticle-mediated enhancement of cellular light capture. In the present study, Fremyella diplosiphon wild type (Fd33) and halotolerant (HSF33-2) strains were grown in solution with 20, 100, and 200 nm-diameter gold nanoparticles (AuNPs) to determine their impact on biomass accumulation, pigmentation, and fatty acid methyl ester (FAME) production. Results revealed a significant increase in growth of Fd33 (0.244 ± 0.006) and HSF33-2 (0.112 ± 0.003) when treated with 200 nm AuNPs. In addition, we observed a significant increase in chlorophyll a accumulation in 200 nm AuNP-treated Fd33 (25.7%) and HSF33-2 (36.3%) indicating that NPs enhanced photosynthetic pigmentation. We did not observe any alteration in FAME composition and biodiesel properties of transesterified F. diplosiphon lipids among all AuNP treatments. Interactions between F. diplosiphon and AuNPs were visualized using scanning electron microscopy. Energy dispersive X-ray spectroscopy confirmed the presence of AuNPs outside cells with aggregation in high cell density locales. Our findings indicate that nanotechnological approaches could significantly enhance growth of the organism with no negative effect on FAME-derived biodiesel properties, thus augmenting F. diplosiphon as a potential biofuel agent.

Direct production of a genetically-encoded immobilized biodiesel catalyst

The use of immobilized enzymes as biocatalysts has great potential to improve the efficiency and environmental sustainability of many industrial processes. Here, we report a novel approach that allows for the direct production of a highly active immobilized lipase within the bacterium Bacillus thuringiensis. Cry3Aa-lipA crystals were generated by genetically fusing Bacillus subtilis lipase A to Cry3Aa, a protein that naturally forms crystals in the bacteria. The crystal framework significantly stabilized the lipase against denaturation in organic solvents and high temperatures, resulting in a highly efficient fusion crystal that could catalyze the conversion of triacylglycerols to fatty acid methyl ester biodiesel to near-completion over 10 cycles. The simplicity and robustness of the Cry-fusion crystal (CFC) immobilization system could make it an appealing platform for generating industrial biocatalysts for multiple bioprocesses.