/pdf/a-realistic-technology-and-engineering-assessment-of-algae-vagir2udsx.pdf

A Realistic Technology and Engineering Assessment of Algae Biofuel Production

Endosperm and embryo tissues from the seeds of Euonymus alatus (Burning Bush) accumulate high levels of 3-acetyl-1,2-diacyl-sn-glycerols (acTAGs) as their major storage lipids. In contrast, the aril tissue surrounding the seed produces long-chain triacylglycerols (lcTAGs) typical of most other organisms. The presence of the sn-3 acetyl group imparts acTAGs with different physical and chemical properties, such as a 30% reduction in viscosity, compared to lcTAGs. Comparative transcriptome analysis of developing endosperm and aril tissues using pyrosequencing technology was performed to isolate the enzyme necessary for the synthesis of acTAGs. An uncharacterized membrane-bound O-acyltransferase (MBOAT) family member was the most abundant acyltransferase in the endosperm but was absent from the aril. Expression of this MBOAT in yeast resulted in the accumulation of acTAGs but not lcTAG; hence, the enzyme was named EaDAcT (Euonymus alatus diacylglycerol acetyltransferase). Yeast microsomes expressing EaDAcT possessed acetyl-CoA diacylglycerol acetyltransferase activity but lacked long-chain acyl-CoA diacylglycerol acyltransferase activity. Expression of EaDAcT under the control of a strong, seed-specific promoter in Arabidopsis resulted in the accumulation of acTAGs, up to 40 mol % of total TAG in the seed oil. These results demonstrate the utility of deep transcriptional profiling with multiple tissues as a gene discovery strategy for low-abundance proteins. They also show that EaDAcT is the acetyltransferase necessary and sufficient for the production of acTAGs in Euonymus seeds, and that this activity can be introduced into the seeds of other plants, allowing the evaluation of these unusual TAGs for biofuel and other applications.

https://www.pnas.org/content/pnas/107/20/9464.full.pdf

A distinct DGAT with sn-3 acetyltransferase activity that synthesizes unusual, reduced-viscosity oils in Euonymus and transgenic seeds

To optimize biodiesel manufacturing, many reported studies have built simulation models to quantify the relationship between operating conditions and process performance. For mass and energy balance simulations, it is essential to know the four fundamental thermophysical properties of the feed oil: liquid density (ρL), vapor pressure (Pvap), liquid heat capacity (CPL), and heat of vaporization (ΔHvap). Additionally, to characterize the fuel qualities, it is critical to develop quantitative correlations to predict three biodiesel properties, namely, viscosity, cetane number, and flash point. Also, to ensure the operability of biodiesel in cold weather, one needs to quantitatively predict three low-temperature flow properties: cloud point (CP), pour point (PP), and cold filter plugging point (CFPP). This article presents the results from a comprehensive evaluation of the methods for predicting these four essential feed oil properties and six key biodiesel fuel properties. We compare the predictions to repor...

/pdf/selection-of-prediction-methods-for-thermophysical-1wcass1h1d.pdf

Selection of Prediction Methods for Thermophysical Properties for Process Modeling and Product Design of Biodiesel Manufacturing

The liquid density of fatty acids can be accurately estimated by the modified Rackett equation over a wide range of temperatures. The modified Rackett equation requires the critical properties and an empirical parameter,Z
 RA
 , for each acid as the basis for computing density as a function of temperature. The liquid density of vegetable oils can be estimated by using mixture properties corresponding to the fatty acid composition and a correction for the triglyceride form. The density prediction is explicitly temperature-dependent.

Density estimation for fatty acids and vegetable oils based on their fatty acid composition

Mathematical modeling of vegetable oil-solvent extraction in a multistage horizontal extractor

Density data for soybean oil/acetone and soybean oil/n-hexane mixtures were measured at 20, 30 and 40 C using a PAAR DMA digital readout calculating precision density meter over the complete range of concentrations. When plotted as molar volume versus molar concentration the mixtures exhibited near ideal linear behavior. To check whether other oil/solvent mixtures behaved in a similar way, data from published literature were replotted in this form and the near ideal linear behavior was observed.

W. Hamm

Papers

Densities of soybean oil/solvent mixtures