Dataset Information

Culturable heavy metal-resistant and plant growth promoting bacteria in V-Ti magnetite mine tailing soil from Panzhihua, China.

ABSTRACT: To provide a basis for using indigenous bacteria for bioremediation of heavy metal contaminated soil, the heavy metal resistance and plant growth-promoting activity of 136 isolates from V-Ti magnetite mine tailing soil were systematically analyzed. Among the 13 identified bacterial genera, the most abundant genus was Bacillus (79 isolates) out of which 32 represented B. subtilis and 14 B. pumilus, followed by Rhizobium sp. (29 isolates) and Ochrobactrum intermedium (13 isolates). Altogether 93 isolates tolerated the highest concentration (1000 mg kg(-1)) of at least one of the six tested heavy metals. Five strains were tolerant against all the tested heavy metals, 71 strains tolerated 1,000 mg kg(-1) cadmium whereas only one strain tolerated 1,000 mg kg(-1) cobalt. Altogether 67% of the bacteria produced indoleacetic acid (IAA), a plant growth-promoting phytohormone. The concentration of IAA produced by 53 isolates was higher than 20 µg ml(-1). In total 21% of the bacteria produced siderophore (5.50-167.67 µg ml(-1)) with two Bacillus sp. producing more than 100 µg ml(-1). Eighteen isolates produced both IAA and siderophore. The results suggested that the indigenous bacteria in the soil have beneficial characteristics for remediating the contaminated mine tailing soil.

SUBMITTER: Yu X

PROVIDER: S-EPMC4154735 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Culturable heavy metal-resistant and plant growth promoting bacteria in V-Ti magnetite mine tailing soil from Panzhihua, China.

Yu Xiumei X Li Yanmei Y Zhang Chu C Liu Huiying H Liu Jin J Zheng Wenwen W Kang Xia X Leng Xuejun X Zhao Ke K Gu Yunfu Y Zhang Xiaoping X Xiang Quanju Q Chen Qiang Q

PloS one 20140904 9

To provide a basis for using indigenous bacteria for bioremediation of heavy metal contaminated soil, the heavy metal resistance and plant growth-promoting activity of 136 isolates from V-Ti magnetite mine tailing soil were systematically analyzed. Among the 13 identified bacterial genera, the most abundant genus was Bacillus (79 isolates) out of which 32 represented B. subtilis and 14 B. pumilus, followed by Rhizobium sp. (29 isolates) and Ochrobactrum intermedium (13 isolates). Altogether 93 i ...[more]

PMID: 25188470

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Project description:Understanding the level of heavy metal contamination coupled with the assessment of environmental and human risks associated with mine waste dumpsites is an important step to initiating efficient measures for mine wasteland restoration, stabilization, and bioremediation. In the present study, concentration of the heavy metals; Copper (Cu), Cobalt (Co), Iron (Fe), Lead (Pb), Manganese (Mn), and Zinc (Zn) in soil from mine waste dumpsites around Kitwe (Sites: TD25 and TD26) and Mufulira (Site: TD10), Zambia, was assessed to determine the level of contamination, ecological risks, and progress made in reclamation. The mine waste dumpsites in the two towns are located in the vicinity of residential areas. Therefore, there is need to provide information for optimization of protocols for post-mining landscape in Zambia and elsewhere to limit soil, river, and groundwater contamination and to accelerate the restoration process . Mean values for soil pH, electrical conductivity, and organic matter varied between 5.9-8.4, 2534.8-538.6 μS/cm, and 0.90-2.75%, respectively. The mean concentrations of heavy metals of TD25, TD26, and TD10 decreased in order of Fe > Cu > Co > Mn > Pb > Zn across all sites. However, the order of overall degree of heavy metal contamination computed using control soil as a baseline in TD25, TD26, and TD10 was Cu > Co > Fe > Pb > Mn > Zn. The pollution load index was 0.355 at TD25, 0.329 at TD26, and 0.189 at TD10, indicating high soil pollution at TD25 and TD26. The Potential Ecological Risk Index for all heavy metals tested at TD25, TD26, and TD10 showed low ecological risk in the vicinity of the studied dumpsites. Furthermore, the present study also showed that the polluted soils around smelter sites and mine waste dumpsites are susceptible to dispersion by wind and water. Additionally, results from TD10 revealed that the initiated remediation of the tailings dam was somewhat successful. Finally, this study provided an updated status regarding the accumulation of heavy metals in mine waste dumpsites of Kitwe and Mufulira, Zambia and baseline information necessary to enhance post-mining landscape reclamation.

Project description:IntroductionThe diversity, nitrogen-fixing capacity and heavy metal tolerance of culturable rhizobia in symbiotic relationship with Pongamia pinnata surviving in vanadium (V) - titanium (Ti) magnetite (VTM) tailings is still unknown, and the rhizobia isolates from the extreme barren VTM tailings contaminated with a variety of metals would provide available rhizobia resources for bioremediation.MethodsP. pinnata plants were cultivated in pots containing the VTM tailings until root nodules formed, and then culturable rhizobia were isolated from root nodules. The diversity, nitrogen-fixing capacity and heavy metal tolerance of rhizobia were performed.ResultsAmong 57 rhizobia isolated from these nodules, only twenty strains showed different levels of tolerance to copper (Cu), nickel (Ni), manganese (Mn) and zinc (Zn), especially strains PP1 and PP76 showing high tolerance against these four heavy metals. Based on the phylogenetic analysis of 16S rRNA and four house-keeping genes (atpD, recA, rpoB, glnII), twelve isolates were identified as Bradyrhizobium pachyrhizi, four as Ochrobactrum anthropic, three as Rhizobium selenitireducens and one as Rhizobium pisi. Some rhizobia isolates showed a high nitrogen-fixing capacity and promoted P. pinnata growth by increasing nitrogen content by 10%-145% in aboveground plant part and 13%-79% in the root. R. pachyrhizi PP1 showed the strongest capacity of nitrogen fixation, plant growth promotion and resistance to heavy metals, which provided effective rhizobia strains for bioremediation of VTM tailings or other contaminated soils. This study demonstrated that there are at least three genera of culturable rhizobia in symbiosis with P. pinnata in VTM tailings.DiscussionAbundant culturable rhizobia with the capacity of nitrogen fixation, plant growth promotion and resistance to heavy metals survived in VTM tailings, indicating more valuable functional microbes could be isolated from extreme soil environments such as VTM tailings.

Project description:Heavy metals (HMs) have become a major environmental pollutant threatening ecosystems and human health. Although hyperaccumulators provide a viable alternative for the bioremediation of HMs, the potential of phytoremediation is often limited by the small biomass and slow growth rate of hyperaccumulators and HM toxicity to plants. Here, plant growth-promoting bacteria (PGPB)-assisted phytoremediation was used to enhance the phytoremediation of HM-contaminated soils. A PGPB with HM-tolerant (HMT-PGPB), Bacillus sp. PGP15 was isolated from the rhizosphere of a cadmium (Cd) hyperaccumulator, Solanum nigrum. Pot experiments demonstrated that inoculation with strain PGP15 could significantly increase the growth of S. nigrum. More importantly, strain PGP15 markedly improved Cd accumulation in S. nigrum while alleviating Cd-induced stress in S. nigrum. Specifically, PGP15 inoculation significantly decreased the contents of H2O2, MDA, and O2·- in S. nigrum, while the activities (per gram plant fresh weight) of SOD, APX, and CAT were significantly increased in the PGP15-inoculated plants compared with the control sample. These results suggested that the interactions between strain PGP15 and S. nigrum could overcome the limits of phytoremediation alone and highlighted the promising application potential of the PGPB-hyperaccumulator collaborative pattern in the bioremediation of HM-contaminated soils. Furthermore, the PGP15 genome was sequenced and compared with other strains to explore the mechanisms underlying plant growth promotion by HMT-PGPB. The results showed that core genes that define the fundamental metabolic capabilities of strain PGP15 might not be necessary for plant growth promotion. Meanwhile, PGP15-specific genes, including many transposable elements, played a crucial role in the adaptive evolution of HM resistance. Overall, our results improve the understanding of interactions between HMT-PGPB and plants and facilitate the application of HMT-PGPB in the phytoremediation of HM-contaminated soils.

Dataset Information

Culturable heavy metal-resistant and plant growth promoting bacteria in V-Ti magnetite mine tailing soil from Panzhihua, China.

Publications

Culturable heavy metal-resistant and plant growth promoting bacteria in V-Ti magnetite mine tailing soil from Panzhihua, China.

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