The microbiology of biomining: development and optimization of mineral-oxidizing microbial consortia

Abstract

Biomining, the use of micro-organisms to recover precious and base metals from mineral ores and concentrates, has developed into a successful and expanding area of biotechnology. While careful considerations are made in the design and engineering of biomining operations, microbiological aspects have been subjected to far less scrutiny and control. Biomining processes employ microbial consortia that are dominated by acidophilic, autotrophic iron-or sulfur-oxidizing prokaryotes. Mineral biooxidation takes place in highly aerated, continuous-flow, stirred-tank reactors or in irrigated dump or heap reactors, both of which provide an open, non-sterile environment. Continuous-flow, stirred tanks are characterized by homogeneous and constant growth conditions where the selection is for rapid growth, and consequently tank consortia tend to be dominated by two or three species of micro-organisms. In contrast, heap reactors provide highly heterogeneous growth environments that change with the age of the heap, and these tend to be colonized by a much greater variety of micro-organisms. Heap micro-organisms grow as biofilms that are not subject to washout and the major challenge is to provide sufficient biodiversity for optimum performance throughout the life of a heap. This review discusses theoretical and pragmatic aspects of assembling microbial consortia to process different mineral ores and concentrates, and the challenges for using constructed consortia in non-sterile industrial-scale operations.

Copper Bioleaching in Chile

“…The inoculation of pure microbial strains or consortia has been proposed [23][24][25], but up to now this has not been a common practice. During heap operation, a great diversity of microbes are present, mostly bacteria and archaea [26][27][28]. The most well-known and first identified bioleaching bacteria are Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, and Acidithiobacillus thiooxidans.…”

Enhancement of Biofilm Formation on Pyrite by Sulfobacillus thermosulfidooxidans

“…They can oxidize ferrous iron, RISCs such as tetrathionate, thiosulfate and elemental sulfur, as well as sulfide minerals in the presence of 0.02% yeast extract. Because of the versatile metabolism and tolerance to a hostile environment characterized by low pH and high metal concentrations, the genus Sulfobacillus has been considered for optimization of microbial consortia [10], and they are crucial in mixed cultures during leaching. It is reported that the smaller proportion of Sulfobacillus in leaching consortia under continuous conditions was correlated with the reduction of chalcopyrite leaching kinetics than in batch mode.…”

Community transcriptomics reveals unexpected high microbial diversity in acidophilic biofilm communities

“…The acid mine drainage (AMD) environment has been established as a model ecosystem, due in part to microbial compositional characteristics that make the biofilms tractable for cultivation-independent molecular analyses (reviewed by Denef et al, 2010b). AMD and other acidic environments have also been extensively studied due to their importance in acid and metal contamination, and application in the biomining industry (reviewed by Rawlings and Johnson, 2007;Gadd, 2010).…”