Gas Technology United States

The second development for which IGT is known world-wide is their work on biodesulfurization. The IGT intellectual property package, developed by Kilbane s group, includes two microorganisms, R. rhodochrous strain ATCC 53968 (IGTS8) and B. sphaericus strain ATCC 53969 as well as the enzymes derived from them and cell-free extracts. The biocatalysts and their use were protected in a series of eight patents (plus one US equivalent) and though in some patents a process is claimed, the main emphasis is on biocatalyst. A summary of these patents and the comparison with the early patents of EBC was given in Chapter 3. The patents were entitled  

The two organisms were capable of cleaving the C—S bond in molecules found in oil fractions in a specific manner. Kilbane s intellectual property (specifically, EP0441462 [67] and EP0445896 [68]) focused on the following  

The invented biocatalysts based on R. rhodochrous strain ATCC No. 53968 and on B. sphaericus strain ATCC No. 53969, were protected not only as whole cell biocatalysts, but also their derivatives. Biocatalyst definition includes in addition to whole cells cell membranes, cell extracts and enzymes from those microorganisms. It should be noted that the first six patents are actually sets of similar patents with the first one providing coverage in Europe and the second one in US. This strategy involves coverage in US as well as Europe (the total number of patents is higher than the number of inventions) however, the allowed claims in US were always smaller than that allowed in Europe. IGT s last patent (May 1996) was filed in July 1994, when they already had begun 

These two strains, B. sphaericus strain ATCC 53969 and R. rhodochrous strain ATCC 53968 discovered by Kilbane as being capable of dibenzothiophene desulfurization were patented as two separate (European) patents [67,91], respectively. These two patents issued by 1991 also described the use of the enzymes derived from these organisms and their cell-free extracts for desulfurization applications. Both strains were reported to carry out selective cleavage of C—S bonds in organic carbonaceous materials. The organism, Bacillus sphaericus strain ATCC 53969, was, however, reported in Exxon patents, to be capable of C—C bond cleavage as well and therefore its ability to perform desulfurization without loss of fuel value is questionable. 

The two patents described above were particularly important in the initiation of the developments of biodesulfurization catalysts. The bioreactor arrays required for operation and growth method constituted key elements in the following developments of the area, which would condition viability and successful path to industrialization. A sulfur bioavailability assay was incorporated into the screen for monitoring the sulfur uptake by the microorganisms, and the concept formed a claim in the patents [67,91], The objective 

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