Biodesulfurization of water‐soluble coal‐derived material by Rhodococcus rhodochrous IGTS8

Abstract

Rhodococcus rhodochrous IGTS8 was previously isolated because of its ability to use coal as its sole source of sulfur for growth. Subsequent growth studies have revealed that IGTS8 is capable of using a variety of organosulfur compounds as sources of sulfur but not carbon. In this article, the ability of IGTS8 to selectively remove organic sulfur from water-soluble coal-derived material is investigated. The microbial removal of organic sulfur from coal requires microorganisms capable of cleaving carbon-sulfur bonds and the accessibility of these bonds to microorganisms. The use of water-soluble coal-derived material effectively overcomes the problem of accessibility and allows the ability of microorganisms to cleave carbon-sulfur bonds present in coal-derived material to be assessed directly. Three coals, two coal solubilization procedures, and two methods of biodesulfurization were examined. The results of these experiments reveal that the microbial removal of significant amounts of organic sulfur from water-soluble coal-derived material with treatment times as brief as 24 h is possible. Moreover, the carbon content and calorific value of biotreated products are largely unaffected. Biotreatment does result, however, in an increased hydrogen and nitrogen content and a decreased oxygen content of the coal-derived material. The aqueous supernatant obtained from biodesulfurization experiments does not contain sulfate, sulfite, or other forms of soluble sulfur at increased concentrations in comparison with control samples. Sulfur removed from water-soluble coal-derived material appears to be incorporated into biomass.

Utilization of organosulphur compounds by axenic and mixed cultures of Rhodococcus rhodochrous IGTS8

“…Rhodococcus rhodochrous IGTS8 is capable of the selective cleavage of carbonsulphur bonds in DBT, yielding 2-HBP as the sole detectable metabolite (Kilbane, 1989(Kilbane, , 1990a. The removal of sulphur from coal and some model compounds by strain IGTS8 has also been demonstrated (Kilbane, 1989(Kilbane, , 1990a(Kilbane, , b, 1991Kilbane & Jackowski, 1992). In this paper, the range of organosulphur compounds metabolized by R. rhodochrous IGTS8 and the kinetics of metabolism of organosulphur compounds by axenic and mixed cell cultures of R. rhodochrous IGTS8 are reported.…”

“…These data imply a close association between strain IGTSS and E. cloacae such that E. cloacae is capable of interrupting the uptake of sulphur by strain IGTS8 cells in the mixed culture, 'stealing' sulphur liberated from DBT. This, plus the fact that polymeric organosulphur compounds far too large to be taken into the cytoplasm of bacterial cells are nonetheless successfully desulphurized by strain IGTS8 (Kilbane, 1991 ;Kilbane & Jackowski, 1992), indicates that desulphurization occurs at the external surface of these cells.…”

“…Media (BSM) and growth conditions for R. rhodochrous IGTS8 (ATCC 53968) have been described previously (Kilbane, 1989(Kilbane, , 1990aKilbane & Jackowski, 1992). The majority of mixed cell culture experiments were mixtures of Enterobacter cloacae and R. rhodochrous IGTS8.…”

“…The majority of mixed cell culture experiments were mixtures of Enterobacter cloacae and R. rhodochrous IGTS8. The sulphur bioavailability assay (Kilbane, 1989(Kilbane, , 1990bKilbane & Jackowski, 1992) was used to monitor the ability of R. rhodochrous IGTS8 to use various organosulphur compounds as sole sources of sulphur. Growth tests using BSM lacking glycerol were performed to determine if R.…”

Biodesulfurization of Sour Crude Oil

“…By the late l980s, R. erythropolis IGTS8, which is a unique strain, showed the highest sulfur removal capability (Kilbane, 1990;Kilbane & Jackowski, 1992). Here, the bacteria of interest is the genus Rhodococcus within the Actinobacteria class, Actinomycetales order, ocardiaceae family, and Rhodococcus species (Kayser, 2002).…”