Co-metabolism of thiocyanate and free cyanide by Exiguobacterium acetylicum and Bacillus marisflavi under alkaline conditions

Lukhanyo Mekuto, Oluwadara Oluwaseun Alegbeleye, Seteno Karabo Obed Ntwampe, Maxwell Mewa Ngongang, John Baptist Mudumbi, Enoch A. Akinpelu

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


The continuous discharge of cyanide-containing effluents to the environment has necessitated for the development of environmentally benign treatment processes that would result in complete detoxification of the cyanide-containing wastewaters, without producing additional environmental toxicants. Since biological detoxification of hazardous chemical compounds has been renowned for its robustness and environmental-friendliness, the ability of the Exiguobacterium acetylicum (GenBank accession number KT282229) and Bacillus marisflavi (GenBank accession number KR016603) to co-metabolise thiocyanate (SCN) and free cyanide (CN) under alkaline conditions was evaluated. E. acetylicum had an SCN degradation efficiency of 99.9 % from an initial SCN concentration of 150 mg SCN/L, but the organism was unable to degrade CN. Consequently, B. marisflavi had a CN degradation efficiency of 99 % from an initial concentration of 200 mg CN/L. Similarly, the organism was unable to degrade SCN; hence, this resulted in the evaluation of co-metabolism of SCN and CN by the two microbial species. Optimisation of operational conditions was evaluated using response surface methodology (RSM). A numeric optimisation technique was used to evaluate the optimisation of the input variables i.e. pH, temperature, SCN and CN concentrations. The optimum conditions were found to be as follows: pH 9.0, temperature 34 °C, 140 mg SCN/L and 205 mg CN/L under which complete SCN and CN degradation would be achieved over a 168-h period. Using the optimised data, co-metabolism of SCN and CN by both E. acetylicum and B. marisflavi was evaluated, achieving a combined degradation efficiency of ≥99.9 %. The high degradative capacity of these organisms has resulted in their supplementation on an active continuous biological degradation system that is treating both SCN and CN.

Original languageEnglish
Article number173
Journal3 Biotech
Issue number2
Publication statusPublished - 1 Dec 2016
Externally publishedYes


  • B. marisflavi
  • Biodegradation
  • Co-metabolism
  • E. acetylicum
  • Free cyanide
  • Thiocyanate

ASJC Scopus subject areas

  • Biotechnology
  • Environmental Science (miscellaneous)
  • Agricultural and Biological Sciences (miscellaneous)


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