PURPOSE: To selectively cleave organic C-S bonds by a microorganism-based biochemical reagent.

CONSTITUTION: This invention relates to a microbial process for selective cleavage of organic C-S bonds by contacting sulfur-contg. organic carbonaceous materials with at least one sulfur-specific reactant agent which may be at least one species of microorganism under growth conditions, an extract of microorganism cell membrane fragments or at least one enzyme associated with a microorganism cell membrane, wherein each sulfur-specific reactant agent has the ability of selective cleavage of organic C-S bonds. Microorganisms of Rhodococcus rhodochrous and Bacillus sphaericus and their derivatives have been found which have the ability of selective cleavage of organic C-S bonds, particularly preferred microorganisms are Rhodococcus rhodochrous strain ATCC 53968 and Bacillus sphaericus strain ATCC 53969 and their derivatives. The C-S bond cleavage may be used for reduction of organically bound sulfur in coal and hydrocarbon oils and in the biochemical inactivation and modification of defensins.