Bioleaching of heavy metals from a contaminated soil using indigenous Penicillium chrysogenum strain F1
ABSTRACT Bioleaching of heavy metals from contaminated soil using Penicillium chrysogenum strain F1 was investigated. Batch experiments were performed to compare leaching efficiencies of heavy metals between one-step and two-step processes and to determine the transformation of heavy metal fractions before and after bioleaching. The results showed that two-step process had higher leaching efficiencies of heavy metals than one-step process. When the mass ratio of soil to culture medium containing P. chrysogenum strain F1 was 5% (w/v), 50%, 35%, 9% and 40% of Cd, Cu, Pb and Zn were removed in one-step process, respectively. The two-step process had higher removals of 63% Cd, 56% Cu, 14% Pb and 54% Zn as compared with one-step process. The results of the sequential extraction showed that the metals remaining in the soil were mainly bonded in stable fractions after bioleaching. The results of TEM and SEM showed that during bioleaching process, although the mycelium of P. chrysogenum was broken into fragments, no damage was obviously observed on the surface of the living cell except for thinner cell wall, smaller vacuoles and concentrated cytoplasm. The result implied that P. chrysogenum strain F1 can be used to remove heavy metals from polluted soil.
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ABSTRACT: Fungi can facilitate phytoremediation of mine tailing soil containing heavy metal(loid)s (HMs). Penicil-lium aculeatum PDR-4 and Trichoderma sp. PDR-16, isolated from the rhizosphere of Pinus koraiensis inmine tailing soil, exhibited high HM tolerance and plant growth-promoting characteristics. The isolatesincreased available P in a 1:1 (w/w) mixture of soil and liquid media by 14–43% and the bioavailabilityof As, Cu, Pb and Zn was also increased. Both isolates exhibited phosphatase, phytase and siderophoreactivity. ACC deaminase activity was greater in PDR-16 than in PDR-4; IAA was produced by PDR-4 but notby PDR-16. Sorghum-sudangrass (Sorghum bicolor × sudanense) produced 37–95% more aboveground drybiomass and contained 74–128% more chlorophyll in inoculated soil. In soil inoculated with both isolates,HM concentrations increased in roots by 109% (As), 39% (Cu), 50% (Pb) and 38% (Zn), and in shoots by72% (As), 69% (Pb) and 82% (Zn) compared to those of control plants (Cu concentration did not increase inshoots). HM bioavailability and available soil P, as well as plant biomass, chlorophyll content and plant As,Pb and Zn concentrations were highest in soil inoculated with both fungi. Results suggest that inoculatingsoil with P. aculeatum PDR-4 and Trichoderma sp. PDR-16 will be beneficial for phytoremediation andproduction of sorghum-sudangrass as a bioenergy crop in HM-contaminated soils.Ecological Engineering 05/2014; 69:186-191. · 3.04 Impact Factor
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ABSTRACT: Purpose The objective of this study was to investigate the bioleaching of heavy metals from contaminated sediments by Aspergillus niger strain SY1. To achieve this, three targets were identified: (1) identify organic acids produced by the isolated A. niger strain SY1 from contaminated sediments, (2) compare the leaching ability and transformation of chemical speciation of heavy metals during the bioleaching processes, and (3) determine the toxic characteristic of sediment before and after bioleaching. Materials and methods The contaminated sediment was collected from the dredging of the Xihe River, China. The A. niger strain SY1 was isolated from this sediment. Bioleaching experiments were carried out in 250 ml autoclaved conical flasks with 10 g autoclaved sediment, 1 ml of spore suspension, and 99 ml culture medium; the flasks were placed in a shaking incubator (220 rpm) at 30 °C for 7 days. Toxicity characteristic leaching procedure (TCLP) tests were carried out according to USEPA-SW846 Method 1311, and the wheat and earthworm toxicity tests were carried out according to OECD “Guidelines for the Testing of Chemicals.” Fractionation of heavy metals was undertaken by the three-step sequential extraction procedure. The metabolites were determined with a HPLC system. Results and discussion There was 11.5 % leaching efficiency of Pb from the polluted sediment in the one-step bioleaching process; while in the two-step bioleaching process, the highest extraction efficiency of Pb was 65.4 %. In one-step bioleaching, 93.5 % Cd, 62.3 % Cu, and 68.2 % Zn were leached out; whereas, the highest metal extraction efficiencies of Cd, Cu, and Zn were 99.5, 56, 71.9, and 76.4 %, respectively, in two-step bioleaching. After the bioleaching, the metals remaining in the sediment were mainly found in the stable fractions. Cd, Pb, Cu, and Zn concentrations in extracted liquor of TCLP tests were reduced to far below the levels in two Chinese standards, and the sediment after bioleaching had a lower toxicity on wheat and earthworm. Conclusions A. niger strain SY1 can effectively remove heavy metals in contaminated sediment. The bioleaching efficiencies of heavy metals in the two-step bioleaching were better than that in one-step bioleaching. After the bioleaching, metals remaining in the sediment were mainly found in the stable fractions, and the toxicity of it was reduced to a level for it to be used safely in landfill or used in land application. A. niger strain SY1 is a cost-effective, environmentally friendly, and efficient bioleacher of heavy metals.Journal of Soils and Sediments 04/2015; 15(4). DOI:10.1007/s11368-015-1076-8 · 2.11 Impact Factor