Gasoline Biodesulfurization DE-FC07-97ID13570. Final Report

摘要

Sulfur in gasoline is not only a source of air pollution, but also plays a significant role in determining the tailpipe emissions of other pollutants, such as nitrogen oxides, carbon monoxide and unburned hydrocarbons. The biological removal of sulfur from gasoline, a process called Biocatalytic Desulfurization (BDS) under development at Enchira Biotechnology Corporation (EBC), is an innovative approach that offers the petroleum industry and the U.S. economy potentially great rewards. The purpose of this project was to develop gasoline BDS technology to the point of readiness for operation in a continuous test unit, which would provide the basis for economically attractive commercial designs. Nine strains were identified to grow with gasoline as sole sulfur source. Two different genes were cloned from Gordonia terrae KGB1 and tested for the ability to support gasoline BDS. The first of these, fmoA, was cloned by screening a KGB1 gene library for the ability to convert indole to indigo (a sulfur-regulated capability in KGB1). The fmoA gene was overexpressed in a gasoline tolerant strain of Pseudomonas putida PpG1 and the recombinant strain was shown to convert thiophene to a dimer of thiophene sulfoxide at rates nearly two orders of magnitude higher than KGB1 could catalyze the reaction. Despite this high activity the recombinant PpG1 was unable to demonstrate any activity against gasoline either in shake flask or in bench-scale gasoline BDS bioreactor.