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Biodiesel derived from vegetable oils has drawn considerable attention with increasing environmental consciousness. We attempted continuous methanolysis of vegetable oil by an enzymatic process. Immobilized Candida antarctica lipase was found to be the most effective for the methanolysis among lipases tested. The enzyme was inactivated by shaking in a mixture containing more than 1.5 molar equivalents of methanol against the oil. To fully convert the oil to its corresponding methyl esters, at least 3 molar equivalents of methanol are needed. Thus, the reaction was conducted by adding methanol stepwise to avoid lipase inactivation. The first step of the reaction was conducted at 30°C for 10 h in a mixture of oil/methanol (1:1, mol/mol) and 4% immobilized lipase with shaking at 130 oscillations/min. After more than 95% methanol was consumed in ester formation, a second molar equivalent of methanol was added and the reaction continued for 14 h. The third molar equivalent of methanol was finally added and the reaction continued for 24 h (total reaction time, 48 h). This three-step process converted 98.4% of the oil to its corresponding methyl esters. To investigate the stability of the lipase, the three-step methanolysis process was repeated by transferring the immobilized lipase to a fresh substrate mixture. As a result, more than 95% of the ester conversion was maintained even after 50 cycles of the reaction (100 d).Paper no. J9045 in JAOCS 76, 789-793 (July 1999). KEY WORDS:Biodiesel, Candida antarctica lipase, immobilized enzyme, methanolysis, vegetable oil.Biodiesel (fatty acid methyl esters) is produced by alcoholysis of vegetable oils and animal fats. The main advantages of biodiesel are its biodegradability, renewability, and improved exhaust emissions. Because of these environmental advantages, biodiesel has drawn considerable attention. Currently, biodiesel is produced from vegetable oils in Europe and North America (1,2), and from waste edible oil in Japan. At present, chemical methods are used for biodiesel production, but these methods have drawbacks, such as, difficulties in the recovery of glycerol, the need for removal of catalyst, and the energyintensive nature of the processes. Furthermore, oils containing free fatty acids and/or water are incompletely transesterified using chemical methods. A biochemical approach can overcome these problems, but has not been adopted industrially because of the high cost of the enzyme catalyst. The establishment of a continuous production process using an immobilized enzyme is strongly needed to decrease the production cost of biodiesel using this approach. Several studies report alcoholyses of vegetable oils and animal fats with primary and secondary alcohols and straightand branched-chain alcohols using lipases as catalysts (3-6). However, these reports do not contain the continuous methanolysis of oils and fats in an organic solvent-free environment. A continuous reaction system without organic solvent is necessary for the industrial production of biodiesel. Our ...

Bacterial abundance and leucine incorporation rate were measured throughout the water column (depth, 4,000-6,000 m) at stations occupied in the equatorial, subtropical, and subarctic Pacific as well as in the Bering Sea during three cruises conducted between 1993 and 1997. In general, depth-dependent decreases of bacterial abundance and leucine incorporation in the bathypelagic layer (depth, Ͼ1,000 m) were well described by a power function with remarkably uniform exponents among distant locations: average exponents were Ϫ0.900 and Ϫ1.33 for abundance and leucine incorporation, respectively. Depth profiles of bacterial properties were complex at some subarctic stations, suggesting lateral transport of organic carbon by local eddies. Organic carbon fluxes from abyssal sediment to overlying water would explain increases in bacterial abundance and leucine incorporation in near-bottom layers. Biomass was twofold to fourfold and the production was threefold to sevenfold greater in subarctic than in subtropical regions. This latitudinal pattern was consistent with the basin-scale distribution of sinking fluxes of particulate organic carbon (POC) reported in the literature. Rates of bacterial carbon uptake accounted for 51% (range, 31-153) and 23% (14-58) of deep sinking POC fluxes in subarctic and subtropical regions, respectively. Average turnover time of deep bacterial assemblages was estimated to be 1-30 yr. These results suggest that deep bacterial biomass and production are generally coupled with sinking POC fluxes and that organic carbon is substantially transformed within bathypelagic environments via a sinking POC → dissolved organic carbon → bacteria pathway, as previously suggested in the mesopelagic zone.

Hepatitis B virus envelope L particles form hollow nanoparticles displaying a peptide that is indispensable for liver-specific infection by hepatitis B virus in humans. Here we demonstrate the use of L particles for the efficient and specific transfer of a gene or drug into human hepatocytes both in culture and in a mouse xenograft model. In this model, intravenous injection of L particles carrying the gene for green fluorescent protein (GFP) or a fluorescent dye resulted in observable fluorescence only in human hepatocellular carcinomas but not in other human carcinomas or in mouse tissues. When the gene encoding human clotting factor IX was transferred into the xenograft model using L particles, factor IX was produced at levels relevant to the treatment of hemophilia B. The yeast-derived L particle is free of viral genomes, highly specific to human liver cells and able to accommodate drugs as well as genes. These advantages should facilitate targeted delivery of genes and drugs to the human liver.