Abstract
A chemolithotrophic bacterium was isolated from sulfur hot spring. According to phenotypic traits and 16-23S rDNA intergenic spacer region analysis, the isolate was identified and named as Acidithiobacillus sp. MR39, which was a gram-negative, rod- shape and non-motile bacterium. The strain was able to grow in a synthetic liquid medium supplemented with the mineral ore as the source of energy. The optimum conditions were found to be within initial pH range of 2.0-2.5, at 34±1˚C and with shaking at 120 rpm. The bacterium had a remarkable potential for mineralization of 88% iron, 75% copper, 59% zinc, 59% nickel and 40% cobalt upon their growth in the liquid media. After adapting the bacterial cells to copper ions in 100 mM for 5-day incubation, biorecovery of Cu increased about 10% comparing to unadapted cells that are able to dissolve approximately 15% of total cu of mineral concentrate. Considering the finding in this study, the strain MR39 offers a great prospect for in situ extraction of metals from various ores along with other indigenous bacteria that can grow under ambient conditions.
Highlights
MATERIAL AND METHODSBioleaching refers to extraction of different minerals using environmentally adapted microorganisms as a cost-benefit and eco-friendly process in low-grade mineral ores (Martínez-Bussenius et al, 2017)
Among the known microorganisms involved in bioleaching process, Acidothiobacillus species has been investigated by many researchers and companies (Raheb et al, 2007; Wei et al, 2018)
The majority of acidophilic bacteria are discovered to be responsible for extraction of several metals such as copper, iron, uranium, gold, among others suggesting their reliability in metal mining activities (Mishra & Rhee, 2014; Pathak et al, 2018; ShahrozKhan et al, 2012; Wang et al, 2017)
Summary
Bioleaching refers to extraction of different minerals using environmentally adapted microorganisms as a cost-benefit and eco-friendly process in low-grade mineral ores (Martínez-Bussenius et al, 2017). These microorganisms have been recognized as the operators in bioreactors processing metal recovery through oxidation reactions (Zhao et al, 2013). In many extremely acidic environments, sulfur-oxidizing microorganisms are known as unique types of highly tolerant to extreme acidic conditions (Wang et al, 2016; Romo et al, 2013) Such bacteria acquire their energy from the oxidation of mineral sulfides for metabolic activity (He et al, 2012; Qiu et al, 2017). We focused our attempts on finding native acidophilus bacteria with interested criteria, which would be suitable for industrial uses
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