A study of chemolithoautotrophic bacterial rhodanese, and its potential contribution to cyanide wastage during cyanidation of biooxidized concentrates

Simple item page
dc.contributor.authorGardner, Murray Newellen_ZA
dc.date.accessioned2014-11-16T20:02:39Z
dc.date.available2014-11-16T20:02:39Z
dc.date.issued1998en_ZA
dc.descriptionBibliography: leaves 119-129.en_ZA
dc.description.abstractRefractory gold-bearing metal-sulfide ores and concentrates can be successfully and economically treated by biooxidation prior to cyanidation. However, one of the major drawbacks of the biooxidation process is the excessive consumption of cyanide during the gold dissolution process. The largest proportion of cyanide wastage is attributed to thiocyanate formation. Thiocyanate can be formed by spontaneous chemical reactions between reactive sulfur species and cyanide. The enzyme rhodanese (thiosulfate: cyanide sulfurtransferase EC 2.8.1.1) is also able to catalyze the formation of thiocyanate using thiosulfate and cyanide as substrates. Therefore, the most relevant members of the microbial consortium responsible for biooxidation of gold-bearing ores or concentrates were investigated to determine whether they were able to contribute to thiocyanate formation by means of a enzyme reaction mechanism indicative of rhodanese. Together with a Thiobacillus caldus strain (T. caldus MNG), isolated from a biooxidation pilot plant, the sulfur-oxidizers Thiobacillus ferrooxidans ATCC 33020 (also able to oxidize iron) and Thiobacillus thiooxidans ATCC 19377 demonstrated rhodanese activity. However, the obligate iron-oxidizer Leptospirillum ferrooxidans DSM 2705 had no detectable rhodanese activity. High levels of rhodanese activity were detected from the mixed microbial population of a biooxidation pilot plant, which appeared to be dominated by T. caldus MNG. This T. caldus strain was initially identified in the biooxidation pilot plant using the PCR based 16S rDNA profiling technique of Rawlings (1995), and the identification confirmed by 16S rDNA sequencing. Therefore, T. caldus MNG is considered the major contributor to the rhodanese activity of the biooxidation pilot plant mixed culture. Within the range of sulfur substrates tested, the rhodanese enzyme of T. caldus MNG behaved exclusively as a thiosulfate: cyanide sulfurtransferase, and the rhodanese activity of T. caldus MNG appeared to be dependent on the physiological state of the cell during batch growth. An attempt to isolate a rhodanese gene from T. caldus MNG by Southern hybridization, using the Azotobacter vinelandii rhdA gene as a probe, was unsuccessful. On balance of the information available from this study, and reported elsewhere, rhodanese activity probably does not contribute as much to thiocyanate formation in the cyanidation plant as does the spontaneous chemical formation of thiocyanate.en_ZA
dc.identifier.apacitationGardner, M. N. (1998). <i>A study of chemolithoautotrophic bacterial rhodanese, and its potential contribution to cyanide wastage during cyanidation of biooxidized concentrates</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Molecular and Cell Biology. Retrieved from http://hdl.handle.net/11427/9686en_ZA
dc.identifier.chicagocitationGardner, Murray Newell. <i>"A study of chemolithoautotrophic bacterial rhodanese, and its potential contribution to cyanide wastage during cyanidation of biooxidized concentrates."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Molecular and Cell Biology, 1998. http://hdl.handle.net/11427/9686en_ZA
dc.identifier.citationGardner, M. 1998. A study of chemolithoautotrophic bacterial rhodanese, and its potential contribution to cyanide wastage during cyanidation of biooxidized concentrates. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Gardner, Murray Newell AB - Refractory gold-bearing metal-sulfide ores and concentrates can be successfully and economically treated by biooxidation prior to cyanidation. However, one of the major drawbacks of the biooxidation process is the excessive consumption of cyanide during the gold dissolution process. The largest proportion of cyanide wastage is attributed to thiocyanate formation. Thiocyanate can be formed by spontaneous chemical reactions between reactive sulfur species and cyanide. The enzyme rhodanese (thiosulfate: cyanide sulfurtransferase EC 2.8.1.1) is also able to catalyze the formation of thiocyanate using thiosulfate and cyanide as substrates. Therefore, the most relevant members of the microbial consortium responsible for biooxidation of gold-bearing ores or concentrates were investigated to determine whether they were able to contribute to thiocyanate formation by means of a enzyme reaction mechanism indicative of rhodanese. Together with a Thiobacillus caldus strain (T. caldus MNG), isolated from a biooxidation pilot plant, the sulfur-oxidizers Thiobacillus ferrooxidans ATCC 33020 (also able to oxidize iron) and Thiobacillus thiooxidans ATCC 19377 demonstrated rhodanese activity. However, the obligate iron-oxidizer Leptospirillum ferrooxidans DSM 2705 had no detectable rhodanese activity. High levels of rhodanese activity were detected from the mixed microbial population of a biooxidation pilot plant, which appeared to be dominated by T. caldus MNG. This T. caldus strain was initially identified in the biooxidation pilot plant using the PCR based 16S rDNA profiling technique of Rawlings (1995), and the identification confirmed by 16S rDNA sequencing. Therefore, T. caldus MNG is considered the major contributor to the rhodanese activity of the biooxidation pilot plant mixed culture. Within the range of sulfur substrates tested, the rhodanese enzyme of T. caldus MNG behaved exclusively as a thiosulfate: cyanide sulfurtransferase, and the rhodanese activity of T. caldus MNG appeared to be dependent on the physiological state of the cell during batch growth. An attempt to isolate a rhodanese gene from T. caldus MNG by Southern hybridization, using the Azotobacter vinelandii rhdA gene as a probe, was unsuccessful. On balance of the information available from this study, and reported elsewhere, rhodanese activity probably does not contribute as much to thiocyanate formation in the cyanidation plant as does the spontaneous chemical formation of thiocyanate. DA - 1998 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1998 T1 - A study of chemolithoautotrophic bacterial rhodanese, and its potential contribution to cyanide wastage during cyanidation of biooxidized concentrates TI - A study of chemolithoautotrophic bacterial rhodanese, and its potential contribution to cyanide wastage during cyanidation of biooxidized concentrates UR - http://hdl.handle.net/11427/9686 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/9686
dc.identifier.vancouvercitationGardner MN. A study of chemolithoautotrophic bacterial rhodanese, and its potential contribution to cyanide wastage during cyanidation of biooxidized concentrates. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Molecular and Cell Biology, 1998 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/9686en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Molecular and Cell Biologyen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherMicrobiologyen_ZA
dc.titleA study of chemolithoautotrophic bacterial rhodanese, and its potential contribution to cyanide wastage during cyanidation of biooxidized concentratesen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
thesis_sci_1998_gardner_mn.pdf
Size:
10.38 MB
Format:
Adobe Portable Document Format
Description:
Download
Collections
Masters