Formation of dimethyloligosulfides in Lake Kinneret

Dimethyloligosulfides were recently identified as a primary source of mild malodorous emissions from Lake Kinneret, Israel. The seasonal odor episodes coincide with a bloom of Peridinium gatunense algae. The possibility that the dimethyloligosulfides are formed by bacterial degradation of Peridinium gatunense lysis products, under oxygen rich conditions was investigated. Several bacterial strains were isolated from the lake. Addition of Peridinium cells to the isolated bacteria cultures yielded dimethyldisulfide and dimethyltrisulfide. One of the bacteria strains, identified as Acinetobacter lwoffii, an obligatory aerobe was singled out for detailed investigation. Addition of Peridinium cells or methionine to the Acinetobacter culture yielded, under aerobic conditions dimethyldisulfide and dimethyltrisulfide. Cystein feed yielded only inorganic oligosulfides, which were converted to dimethylsulfides by addition of d³-methyliodide.