Iron Sulfide Production by Shewanella Strain Isolated from Black Powder

Microbially-influenced corrosion (MIC) is a serious problem affecting oil and gas industry facilities throughout the world. Traditionally, the sulphate-reducing bacteria group has been considered the foremost responsible for MIC. However, recent studies suggest that other bacteria such as metal-reducing bacteria and methanogens may play a key role in MIC. Shewanella are facultative anaerobic iron-reducing bacteria that are well known for their versatile metabolism. Because of their ability to reduce ferric iron and sulphite, oxidize hydrogen gas, and produce sulphide, these bacteria may be involved in MIC. In the present study, the corrosive activity of a strain of Shewanella sp was investigated. This strain was isolated from a gas pipeline (black powder) and identified by 16S rDNA sequence analysis. Experiments were conducted to analyse the potential involvement of Shewanella sp in MIC. The corrosion products were characterized by X-ray diffractometry identifying iron sulphides, iron oxides, and sulphur. Our results indicate that the strain isolated plays a key role in corrosion problems in gas pipelines. Further studies related to the interaction between Desulfovibrio and Shewanella, and its implications to biocorrosion are underway, as well as DGGE analysis from several gas pipeline samples. Key-words: black powder, MIC, Shewanella