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Meng Y.,China Agricultural University | Meng Y.,Qinhuangdao Leading Science and Technology Development Co. | Wang G.,China Agricultural University | Yang N.,Qinhuangdao Leading Science and Technology Development Co. | And 6 more authors.
Biotechnology for Biofuels | Year: 2011

Background: Enzymatic biodiesel production by transesterification in solvent media has been investigated intensively, but glycerol, as a by-product, could block the immobilized enzyme and excess n-hexane, as a solution aid, would reduce the productivity of the enzyme. Esterification, a solvent-free and no-glycerol-release system for biodiesel production, has been developed, and two-step catalysis of soybean oil, hydrolysis followed by esterification, with Yarrowia lipolytica lipase is reported in this paper. Results: First, soybean oil was hydrolyzed at 40°C by 100 U of lipase broth per 1 g of oil with approximately 30% to 60% (vol/vol) water. The free fatty acid (FFA) distilled from this hydrolysis mixture was used for the esterification of FFA to fatty acid ethyl ester by immobilized lipase. A mixture of 2.82 g of FFA and equimolar ethanol (addition in three steps) were shaken at 30°C with 18 U of lipase per 1 gram of FFA. The degree of esterification reached 85% after 3 hours. The lipase membranes were taken out, dehydrated and subjected to fresh esterification so that over 82% of esterification was maintained, even though the esterification was repeated every 3 hours for 25 batches. Conclusion: The two-step enzymatic process without glycerol released and solvent-free demonstrated higher efficiency and safety than enzymatic transesterification, which seems very promising for lipase-catalyzed, large-scale production of biodiesel, especially from high acid value waste oil. © 2011 Meng et al; licensee BioMed Central Ltd.

Meng Y.-H.,Beijing University of Chemical Technology | Meng Y.-H.,Qinhuangdao Leading Science and Technology Development Co. | Chen B.-Q.,Beijing University of Chemical Technology | Yang N.,Qinhuangdao Leading Science and Technology Development Co. | And 3 more authors.
Journal of Biobased Materials and Bioenergy | Year: 2010

Oleic acid is a major component in fatty acid, a by-product in refining of vegetable oil. In this study, oleic acid was esterified with ethanol using Yarrowia lipolytica lipase immobilized on fabric membranes. Water content and ethanol addition method affected the reaction equilibrium. Esterification degree reached 94.5% under optimal water content and stepwise ethanol addition at 30 °C. The optimal condition allowed 82 batches and 30 days with >66.3% and 82.6% conversion, respectively, in 1.41 g oleic acid and 20% immobilized Y. lipolytica lipase. The method described is suitable for large-scale production in view of the lower cost, higher substrate concentration, and greater production volume without use of an organic solvent. Copyright © 2010 American Scientific Publishers. All rights reserved.

Huang B.,Beijing University of Chemical Technology | Qin P.,Beijing University of Chemical Technology | Xu Z.,Qinhuangdao Leading Science and Technology Development Co. | Zhu R.,Qinhuangdao Leading Science and Technology Development Co. | Meng Y.,Qinhuangdao Leading Science and Technology Development Co.
Bioresource Technology | Year: 2011

CaCl2 was used as a novel additive to enhance poly-(γ-glutamic acid) (γ-PGA) production by Bacillus subtilis strain CGMCC 2108. Addition of CaCl2 to medium effectively reduced viscosity of culture broth, and increased consumption of extracellular glutamate by 11.4%, leading to γ-PGA yield of 9.07g/l, compared to 7.88g/l in control. CaCl2 also increased activities of three key enzymes around the crucial 2-oxoglutarate branch of the γ-PGA biosynthesis pathway: isocitrate dehydrogenase (ICDH), glutamate dehydrogenase (GDH), and 2-oxoglutarate dehydrogenase complex (ODHC). In particular, GDH activity was increased more than 8-fold, indicating that more 2-oxoglutarate was directed to synthesis of glutamate, the substrate of γ-PGA. Interestingly, the molecular weight of γ-PGA remained constant regardless of CaCl2 addition. © 2010 Elsevier Ltd.

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