Use of a novel fluorinated organosulfur compound to isolate bacteria capable of carbon-sulfur bond cleavage.
The vacuum residue fraction of heavy crudes contributes to the viscosity of these oils. Specific microbial cleavage of C-S bonds in alkylsulfide bridges that form linkages in this fraction may result in dramatic viscosity reduction. To date, no bacterial strains have been shown conclusively to cleave C-S bonds within alkyl chains. Screening for microbes that can perform this activity was greatly facilitated by the use of a newly synthesized compound, bis-(3-pentafluorophenylpropyl)-sulfide (PFPS), as a novel sulfur source. The terminal pentafluorinated aromatic rings of PFPS preclude growth of aromatic ring-degrading bacteria but allow for selective enrichment of strains capable of cleaving C-S bonds. A unique bacterial strain, Rhodococcus sp. strain JVH1, that used PFPS as a sole sulfur source was isolated from an oil-contaminated environment. Gas chromatography-mass spectrometry analysis revealed that JVH1 oxidized PFPS to a sulfoxide and then a sulfone prior to cleaving the C-S bond to form an alcohol and, presumably, a sulfinate from which sulfur could be extracted for growth. Four known dibenzothiophene-desulfurizing strains, including Rhodococcus sp. strain IGTS8, were all unable to cleave the C-S bond in PFPS but could oxidize PFPS to the sulfone via the sulfoxide. Conversely, JVH1 was unable to oxidize dibenzothiophene but was able to use a variety of alkyl sulfides, in addition to PFPS, as sole sulfur sources. Overall, PFPS is an excellent tool for isolating bacteria capable of cleaving subterminal C-S bonds within alkyl chains. The type of desulfurization displayed by JVH1 differs significantly from previously described reaction results.
Van Hamme
Jonathan D
JD
National Centre for Upgrading Technology, Devon, Alberta T9G 1A8, Canada. jvanhamme@cariboo.bc.ca
Fedorak
Phillip M
PM
Foght
Julia M
JM
Gray
Murray R
MR
Dettman
Heather D
HD
D001419:Bacteria / Q000302:isolation & purification* / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002244:Carbon / Q000378:metabolism; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry / Q000378:metabolism*; D010578:Petroleum / Q000378:metabolism* / Q000382:microbiology*; D012240:Rhodococcus / Q000302:isolation & purification / Q000378:metabolism; D013440:Sulfides / Q000737:chemistry / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism; D014783:Viscosity
D006845:Hydrocarbons, Fluorinated; D010578:Petroleum; D013440:Sulfides; D013455:Sulfur; D002244:Carbon