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Insight to the early-stage adsorption mechanism of moderately thermophilic consortia and intensified bioleaching of chalcopyrite

Liu, Ronghui, Chen, Jing, Zhou, Wenbo, Cheng, Haina, Zhou, Hongbo
Biochemical engineering journal 2019 v.144 pp. 40-47
Acidithiobacillus caldus, Leptospirillum ferriphilum, adsorption, bioaugmentation, biofilm, bioleaching, confocal laser scanning microscopy, copper, interspecific competition, leaching, models, quantitative polymerase chain reaction, sorption isotherms
Biofilm plays an important role on chalcopyrite bioleaching and early-stage adsorption of cells are essential for biofilm formation. In this study, the interspecies interaction and the early adsorption behavior of moderately thermophilic consortia (Ferroplasma thermophilum, Leptospirillum ferriphilum and Acidithiobacillus caldus) were investigated. qPCR and Confocal laser scanning microscopy (CLSM) were adopted in this study. The bacterial adsorption experiments showed that three pure culture could attach properly on chalcopyrite within a short time and the equilibrium data was well fitted with both Langmuir and Freundlich models. Meanwhile, compared to Ferroplasma thermophilum, Leptospirillum ferriphilum and Acidithiobacillus caldus showed coadsorption relationship and owned competitive adavantages in the binary culture system. The adsorption of both Leptospirillum ferriphilum and Acidithiobacillus caldus together promoted the attachment of Ferroplasma thermophilum. The intensified bioleaching assays based on this attachment mechanism showed that the bioaugmentation of the advanced leaching stage by adapated Ferroplasma thermophilum significantly accelerated copper extraction. Confocal laser scanning microscopy (CLSM) results confirmed the improved biofilm formation by bioaugmentation with adapted Ferroplasma thermophilum. Furthermore, a mechanism model for intensifying chalcopyrite bioleaching by biofilm was established. The results revealed that attachment was complicated but provided an efficient approach to intensify chalcopyrite bioleaching.