Task 1.10 -- Biodesulfurization, Year 2. Semi-annual report, January 1--June 30, 1995

The main focus in this task is the application of desulfurization enzymes to remove sulfur from crude oil, diesel fuel, or resid precursors for needle cokes. The most important question to be answered is how to utilize the Rhodococcus desulfurization complex in a nonaqueous solvent or medium, such as the oil itself. Successful application of nonaqueous enzymology to this problem will involve finding ways to stabilize the active conformations of the enzymes and provide for easy recovery of the enzymes, perhaps in an immobilized-enzyme packed-bed reactor. A second objective is to explore biological systems that can catalyze the cleavage or organometallics in fossil fuels, such as metal porphyrins. A biodemetallation function could greatly aid in the refining of high-metal, high-sulfur crudes and bitumens. During this period, work was initiated to develop new rapid and highly quantitative assays for specific desulfurization activities in isolated and separated enzyme fractions. The preparation of water-soluble chlorophyllin was carried out for use in assaying for demetallation activity in microorganisms. Cleavage of the dark green porphyrin system in the chlorophyllin will be an indicator of activity that may be useful for cleavage of other metal porphyrins in crudes and bitumens