Bacteria of the sulphur cycle: An overview of microbiology, biokinetics and their role in petroleum and mining industries

Bacteria of the sulphur cycle, in particular sulphate reducing and sulphide oxidizing bacteria, are of immense importance from the industrial and environmental point of views. While biogenic production of H2S by sulphate reducing bacteria creates severe processing and environmental problems for the petroleum industry and agriculture sector, when used in a properly designed and controlled bioreactor sulphate reducing bacteria could play an instrumental role in the treatment of acid mine drainage, a major environmental challenge faced by the mining industry. Biooxidation of sulphide and intermediary sulphur compounds carried out by sulphide oxidizing bacteria are crucial in biotreatment of acid mine drainage and in the bioleaching of refractory minerals. Moreover, sulphide oxidizing bacteria are known as major players in the in situ removal of H2S from the onshore and offshore oil reservoirs and are used in the ex situ processes for the treatment of sour gas and sulphide laden waters. Owing to the numerous environmental and industrial applications, the bacteria of the sulphur cycle have been subject of numerous studies. The present article aims to provide an overview of the microbiology, biokinetics, current and potential applications of the bacteria of sulphur cycle and the reactions which are carried out by these versatile microorganisms. Special consideration is given to the role of these bacteria in the biotreatment of acid mine drainage, oil reservoir souring and the treatment of H2S-containing gaseous and liquid streams.