View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Institute of Hydrobiology, Chinese Academy Of Sciences Extremophiles (2018) 22:851–863 https://doi.org/10.1007/s00792-018-1042-7 ORIGINAL PAPER Bioleaching of copper‑ and zinc‑bearing ore using consortia of indigenous iron‑oxidizing bacteria Wasim Sajjad1,2 · Guodong Zheng1 · Gaosen Zhang3 · Xiangxian Ma1 · Wang Xu1,2 · Suliman Khan2,4 Received: 28 May 2018 / Accepted: 9 July 2018 / Published online: 19 July 2018 © Springer Japan KK, part of Springer Nature 2018 Abstract Indigenous iron-oxidizing bacteria were isolated on modifed selective 9KFe­ 2+ medium from Baiyin copper mine stope, China. Three distinct acidophilic bacteria were isolated and identifed by analyzing the sequences of 16S rRNA gene. Based on published sequences of 16S rRNA gene in the GenBank, a phylogenetic tree was constructed. The sequence of isolate WG101 showed 99% homology with Acidithiobacillus ferrooxidans strain AS2. Isolate WG102 exhibited 98% similarity with Leptospirillum ferriphilum strain YSK. Similarly, isolate WG103 showed 98% similarity with Leptospirillum ferrooxidans strain L15. Furthermore, the biotechnological potential of these isolates in consortia form was evaluated to recover copper and zinc from their ore. Under optimized conditions, 77.68 ± 3.55% of copper and 70.58 ± 3.77% of zinc were dissolved. During the bioleaching process, analytical study of pH and oxidation–reduction potential fuctuations were monitored that refected efcient activity of the bacterial consortia. The FTIR analysis confrmed the variation in bands after treatment with consortia. The impact of consortia on iron speciation within bioleached ore was analyzed using Mössbauer spectroscopy and clear changes in iron speciation was reported. The use of indigenous bacterial consortia is more efcient compared to pure inoculum. This study provided the basic essential conditions for further upscaling bioleaching application for metal extraction. Keywords Bioleaching · Iron-oxidizing bacteria · Acidithiobacillus ferrooxidans · Mössbauer spectroscopy Introduction In human civilization, metal extraction has been an essen- tial activity since Bronze and Iron times. Depletion of high- grade ore resources due to global rise in human population Communicated by A. Driessen. and industrial development has increased the demands of metals. Over the previous several years, extraction of met- * Guodong Zheng als from low- and lean-grade ores using microorganisms [email protected] has been developed into an efective and growing area in 1 Key Laboratory of Petroleum Resources, Gansu Province/ biotechnology (Panda et al. 2015). These microorganisms Key Laboratory of Petroleum Resources Research, Institute catalyze the metals recovery by dissolution of metals present of Geology and Geophysics, Chinese Academy of Sciences, in low-grade sulfde minerals through bioleaching technique Lanzhou 730000, People’s Republic of China or dissolve sulfde minerals to unlock the associated met- 2 University of Chinese Academy of Sciences, Beijing 100049, als within refractory ores (biooxidation) such as gold that People’s Republic of China would be fnally extracted through conventional methods 3 Key Laboratory of Extreme Environmental Microbial (Johnson 2013). Bioleaching has been successfully applied Resources and Engineering, Gansu Province/Key Laboratory of Desert and Desertifcation, Northwest Institute for copper extraction from secondary copper sulfde ores. of Eco‑Environment and Resources, Chinese Academy Today, about 20–25% of copper production is achieved of Sciences, Lanzhou, People’s Republic of China through bio-hydrometallurgical techniques (Panda et al. 4 The Key Laboratory of Aquatic Biodiversity 2014). Reduction of high-grade ore resources is not only and Conservation, Sciences, Institute of Hydrology, concern for mining industry but the concurrent increase in Chinese Academy of Sciences Wuhan, Hubei 430072, low-grade ores leads to numerous environmental issues and People’s Republic of China Vol.:(0123456789)1 3 852 Extremophiles (2018) 22:851–863 occupies additional land area because of higher dump activi- Isolation of iron‑oxidizing bacteria ties (Panda et al. 2015). Several selected bacteria are gaining momentum in Indigenous iron-oxidizing bacteria were isolated by inocu- bioleaching to extract metals from their respective ores in lating acid mine drainage (AMD) water collected from Bai- more economic and environmentally friendly way (Zeng yin copper mine stope, China in a highly selective 9KFe 2+ et al. 2015; Mishra et al. 2016; Yang et al. 2016). Numerous medium with pH 1.5 (Silverman and Lundgren 1959). The 2+ acidophilic chemolithotrophic bacteria have been reported composition of the 9KFe medium (g/L): [(NH4)2SO4, 3.0; Acid- and characterized. Iron- and sulfur-oxidizing bacteria K2HPO4, 0.5; MgSO4·7H2O, 0.5; KCl, 0.1 and Ca(NO3)2, ithiobacillus ferrooxidans that efciently acts for dissolution 0.012] separately autoclaved in distilled water (900 mL) of metals from their respective ores through a biochemical having pH 2.0. Hydrated ferrous sulfate (FeSO 4·7H2O) of mechanism that is now well explained (Sand et al. 2001; 44.4 g was dissolved in 100 mL of distilled water having pH Osorio et al. 2013). In addition, the use of sulfur-oxidizing 1.5 and sterilized by fltration (0.22 μm Millipore GVWP Acidithiobacillus thiooxidans along with iron-oxidizing flters) and mixed with the basal salt solution and fnal pH bacteria established a remarkably efective consortium for of 1.5 was adjusted with diluted sulfuric acid. AMD water of extraction of heavy metals from their ores and industrial 5 mL was inoculated in 95 mL of 9KFe2+ media in 250-mL wastes (Baba et al. 2011; Panda et al. 2013b). Such consortia Erlenmeyer fasks and incubated at 150 rpm, 30 ± 0.5 °C for of iron- and sulfur-oxidizing acidophiles are difcult to con- 15 days and control was run in parallel. The media color was taminate by unwanted microorganisms that make consortia regularly checked for growth confrmation of iron oxidizers. industrially important for novel applications in many sectors Culture broth of 2 mL was re-inoculated to fresh 9KFe 2+ (Mishra et al. 2016; Zhu et al. 2011). Bioleaching studies medium and re-incubated. This practice was repeated three of several minerals have exhibited satisfactory recovery of times and bacteria were harvested through centrifugation at metals using acidophilic bacteria. However, some difcul- 14000 rpm for 20 min at 4 ± 0.5 °C. The pellet containing ties such as higher sensitivity of bacterial cell wall towards cells was resuspended in sterile acidifed water (pH 1.5) and pulp density, lower ability of metal tolerance, and higher put into sterile separating funnel and incubated overnight energy requirement to maintain microbial populations have at 4 ± 0.5 °C. All the suspended ferric iron particles were limited its applications to upscale. Nowadays, attention has settled down and the milky supernatant containing bacteria been given to use of acidophilic consortia in bioleaching was collected and again centrifuged at 14000 rpm for 20 min processes (Panda et al. 2012, 2013a). Recently, consortia at 4 ± 0.5 °C. The obtained pellet was washed two times of acidophilic bacteria such as At. ferrooxidans, At. thioox- with sterile acidifed water. Cells collected at pellet were idans, and Leptospirillum ferrooxidans have shown auspi- suspended into sterile acidifed water and spread 100 µL cious results for copper extraction from low-grade ores and on solid 9KFe2+ medium of fnal pH 2.5 having agarose a favored consortium for large-scale heap bioleaching pro- (0.5% w/v separately sterilized in 100 mL distilled water) as cess (Panda et al. 2012, 2015). It is strongly believed that a solidifying agent and incubated at 30 ± 0.5 °C for 20 days. the indigenous microorganisms obtained from the same site Plates were regularly checked for growth of bacteria, colo- would be more efcient to recover metals from the ores as nies were sub-cultured to purify and preserved in 20% glyc- indigenous bacteria are more compatible with the mineral- erol at − 80 ± 0.5 °C. ogy of the rocks. In view of the above facts, culturable diver- sity of acidophilic iron-oxidizing bacteria was studied from Baiyin copper mine stope, China. Owing to the reputation DNA extraction and phylogenetic analysis of these commercially vital bacteria, further, the biotechno- logical potential of these indigenous bacteria in consortia In the late exponential phase, the bacterial cells were har- form was evaluated to recover copper and zinc from the ore vested through centrifugation and commercially available body. Physico-chemical parameters have been optimized for DNA isolation kit was used according to manufacturer efcient metal extraction and appropriate conditions have instruction for DNA extraction (ThermoFisher Scientifc been established for upscaling the study. A29790). The extracted DNA was resuspended in 70 μL TE bufer mixed with RNase and its quantity and quality was assessed on agarose gel 0.8% (w/v) and by NanoDrop ND-1000 spectrophotometer (NanoDrop Technologies, Materials and methods Wilmington, USA) and stored at 4 ± 0.5 °C for subsequent analysis. The entire chemicals and reagents consumed in current For the identifcation of bacterial isolates, sequencing research were of analytical grade and purchased from Sigma- of 16S rRNA gene was performed. Almost full length of Aldrich Chemical Co and Merck. 1 3 Extremophiles (2018) 22:851–863 853 the gene was amplifed from extracted DNA using 27F’ indigenous iron-oxidizing bacterial strains for copper and (5′-AGA GTT TGA TCC TGG CTC AG-3′) and 1492R′ zinc dissolution. (5-TAC GYT ACC TTG TTA CGA CTT-3) bacterial prim- ers (Hassanshahian and Ghoebani 2018). PCR reaction Bacteria and culture conditions mixture of 20 µL consisted of DNA sample 1 µL, 2 µL of deoxynucleotide triphosphate (dNTP), PCR bufer 2, 2 µL Consortia of indigenous iron-oxidizing bacteria were used each reverse and forward primer, ex taq DNA polymer- as an inoculum in the present study of bioleaching. For ase 0.5 µL (Takara Shuzo, Otsu) and 10.5 µL PCR water.