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Microbial communities associated with the co-metabolism of free cyanide and thiocyanate under alkaline conditions

Mekuto, Lukhanyo, Ntwampe, SetenoKarabo Obed, Mudumbi, JohnBaptist N.
3 Biotech 2018 v.8 no.2 pp. 93
Bacillus (bacteria), Klebsiella oxytoca, Myroides, Proteus, Providencia, Pseudomonas, biodegradation, cyanides, enzymes, microbial communities, ribosomal RNA, thiocyanates
This study focused on the identification of free cyanide (CDO) and thiocyanate (TDO) degrading microbial communities using a culture-dependent and independent approach. Culturable microbial species were isolated from the CDOs (n = 13) and TDOs (n = 18). The CDOs were largely dominated by Bacillus sp. while the TDOs were dominated by Bacillus sp., Klebsiella oxytoca, Providencia sp. and Pseudomonas sp. However, 16S rRNA amplicon gene-sequencing revealed the complexity and diversity of the microbial communities in contrast to the organisms that were detected using culture-dependent technique. Overall, the organisms were mainly dominated by Myroides odoratimimus and Proteus sp. at 37.82 and 30.5% for CDOs, and 35.26 and 17.58% for TDOs, respectively. The co-culturing of the CDOs and TDOs resulted in biochemical changes of key metabolic enzymes, and this resulted in the complete degradation of CN⁻ and SCN⁻ simultaneously; a phenomenon which has not been witnessed, especially under alkaline conditions. Current ongoing studies are focused on the application of these organisms for the biodegradation of CN⁻ and SCN⁻ in a continuous system, under changing operational parameters, to assess their effectiveness in the biodegradation of CN⁻ and SCN⁻.