Bioreduction of chromium (VI) by Bacillus sp. isolated from soils of iron mineral area

doi:10.1016/j.ejsobi.2009.06.009

European Journal of Soil Biology

Volume 45, Issues 5–6, September–December 2009, Pages 483-487

https://doi.org/10.1016/j.ejsobi.2009.06.009 Get rights and content

Abstract

Extensive use of chromium in industry has caused environmental contamination. Chromium-resistant bacteria are capable of reducing toxic Cr (VI) to less toxic Cr (III). Eight isolates, which can grow on LB agar containing 500 mg/L of Cr (VI), were isolated from soil samples of iron mineral area. The bacterial isolates were identified as Bacillus sp. by the 16S rRNA gene sequences. Phylogenetic tree analysis indicates the isolates can be divided into two groups. The bacterial isolates can be resistant to other heavy metals and reduce Cr (VI) at different levels. One bacterial isolate (MDS05), which can tolerate 2500 mg/L Cr (VI) and was able to reduce almost 100% of Cr (VI) at the concentration of 10 mg/L in 24 h, was selected to study the effects of some environmental factors such as pH, temperature, and time on Cr (VI) reduction and growth. The cell growth of MDS05 was affected by the presence of Cr (VI), especially at the concentration of 100 mg/L. It reduced more amount of Cr (VI) under a wide range of concentrations from 5 to 50 mg/L, and reduction was optimum at 37 °C and pH 8. MDS05 showed great promise for use in Cr (VI) detoxification under a wide range of environmental conditions.

Introduction

Chromate has many industrial applications and defense applications such as stainless steel, chrome plating, leather tanning, dyes, pigments and nuclear weapons production, and often causes a widespread environmental contaminant [1]. It generally exists in two stable oxidation states, trivalent or chromium III and hexavalent or chromium VI. The trivalent chromium is less toxic and mobile, while the hexavalent form of chromium, Cr (VI), is highly soluble and a strong oxidizing agent that is reduced intracellularly to Cr⁵⁺ and reacts with nucleic acids and other cell components to produce mutagenic and carcinogenic effects on biological systems [2]. Hence, reduction of Cr (VI) to Cr (III) is an attractive and useful method for Cr (VI) pollution [3].

Conventional physicochemical methods for removing toxic CrO₄^2- include electrochemical treatment, precipitation, ion exchange, evaporation, reverse osmosis, and adsorption on activated coal. However, most of these methods are often inefficient and very expensive especially for metals at low concentration [2], [4], and hence biological approach has been considered as an alternative remediation for chromium(VI) contamination due to the lower costs and the significant smaller quantities of the produced sludge [5].

Biological approach could be initiated by the microbial reduction of Cr (VI). Microbial populations in Cr (VI) polluted environments adapt to toxic concentrations of Cr (VI) and become chromium (VI)-resistant and chromium (VI)-reducing strains [6]. In previous researches, a number of microorganisms have been reported to be able to reduce Cr (VI), including strains of Pseudomonas [7], [8], Bacillus [9], Enterobacter [10], [11], Escherichia coli [12], Shewanella [13], [14], and several other bacterial isolates [15], [16].

The objectives of this study was to isolate bacteria from iron mineral area where the hexavalent chromium and other heavy metal level is quite high, to measure the bacterial minimum inhibitory concentrations (MIC) of heavy metals, and to research the characterization of factors involved in hexavalent chromium reduction. These results obtained in this study may provide the useful knowledge for the bioremediation of chromate pollution.

Section snippets

Soil samples and isolation of bacteria

Soil samples were collected from iron mineral area in HuBei Province, China that proved many minerals such as iron, manganese, chromium and copper. For the isolation of bacteria, soil samples were serially diluted and plated onto Luria–Bertani (LB) agar. The molten medium was supplemented with Cr (VI) as K₂CrO₄ to final concentration 500 mg/L [2]. The Cr(VI) stock solution was filter sterilized with a 0.22 μm membrane filter. Plates were incubated at 37 °C for 48 h. Colonies of different

Screening and identification of bacterial isolates

Eight isolates (MDS01-MDS08) with inherent ability of 500 mg/L Chromate resistance have been isolated from the soils of iron mineral area in HuBei Province, China. The isolates showed significant growth in LB medium containing 500 mg/L Cr (VI). All the isolates formed spores and were gram-positive. The isolates were identified by initial PCR amplification of the 16S rRNA genes, which were then sequenced, and the nucleotide sequences were analyzed for homology using BlastN (Table 1). The results

Discussion

Metal-polluted environments pose serious health and ecological risk. Metal containing industrial effluents constitute a major source of metallic pollution [23]. Soil is a common environment for Cr(VI) contamination, and most Cr (VI)-resistant bacteria reported to date have been isolated from soil. Here we describe the identification of 8 Cr(VI)-resistant bacterial isolates and the characterization of Cr(VI) reduction by selected isolate. Most of the isolates were able to reduce Cr(VI), but at

Conclusions

Microorganisms with the ability to tolerate and reduce Cr (VI) can be used for detoxification of environment contaminated with Cr (VI). In this study, we report the isolation and screening of eight Cr (VI)-resistant bacterial isolates and the characterization of Cr (VI) reduction. Isolate MDS05 that exhibited more resistance to different heavy metals and substantial reduction of Cr (VI) was further studied. The factors that affected Cr(VI) reduction studied here (pH, temperature, and Cr

Acknowledgements

This work was supported by a grant from Key Natural Science Foundation of South-Central University for Nationalities (YZZ06013).

References (31)

Y. Liu et al.
Cr (VI). reduction by Bacillus sp. isolated from chromium landfill
Process Biochem.
(2006)
S. Zafar et al.
Metal tolerance and biosorption potential of filamentous fungi isolated from metal contaminated agricultural soil
Bioresour. Technol.
(2007)
S. Congeevaram et al.
Biosorption of chromium and nickel by heavy metal resistant fungal and bacterial isolates
J. Hazard. Mater.
(2007)
H. Guha et al.
Kinetics of chromium (VI) reduction by a type strain Shewanella alga under different growth conditions
Environ. Pollut.
(2001)
M.T. Hassan et al.
Identification of a gene cluster, czr, involved in cadmium and zinc resistance in pseudomonas aeruginosa
Gene
(1999)
A. Hassen et al.
Effects of heavy metals on Pseudomonas aeruginosa and Bacillus huringiensis
Bioresour. Technol.
(1998)
E.I. Yilmaz
Metal tolerance and biosorption capacity of Bacillus circulans strain EB1
Res. Microbiol.
(2003)
M.A. Amoozegar et al.
Evaluation of hexavalent chromium reduction by chromate-resistant moderately halophile, Nesterenkonia sp. strain MF2
Process Biochem.
(2007)
Y.T. Wang et al.
Factors affecting hexavalent chromium reduction in pure cultures of bacteria
Wat. Res.
(1995)
S. Sultan et al.
Reduction of toxic hexavalent chromium by Ochrobactrum intermedium strain SDCr-5 stimulated by heavy metals
Bioresour. Technol.
(2007)

K. Chourey et al.

Global molecular and morphological effects of 24-hour chromium(vi) exposure on Shewanella oneidensis MR-1

Appl. Environ. Microbiol.

(2006)

F.A.O. Camargo et al.

Chromate reduction by chromium-resistant bacteria isolated from soils contaminated with dichromate

J. Environ. Qual.

(2003)

B. Prasenjit et al.

Uptake of chromium by Aspergillus foetidus

J. Mater. Cycles Waste Manag.

(2005)

A.H. Alvarez et al.

Chromate efflux by means of the chrA chromate resistance protein from Pseudomonas aeruginosa

J. Bacteriol.

(1999)

L.H. Bopp et al.

Chromate resistance and reduction in Pseudomonas fluorescence strain LB300

Arch. Microbiol.

(1988)

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Original articleBioreduction of chromium (VI) by Bacillus sp. isolated from soils of iron mineral area

Abstract

Introduction

Section snippets

Soil samples and isolation of bacteria

Screening and identification of bacterial isolates

Discussion

Conclusions

Acknowledgements

Process Biochem.

Bioresour. Technol.

J. Hazard. Mater.

Environ. Pollut.

Gene

Bioresour. Technol.

Res. Microbiol.

Process Biochem.

Wat. Res.

Bioresour. Technol.

Global molecular and morphological effects of 24-hour chromium(vi) exposure on Shewanella oneidensis MR-1

Appl. Environ. Microbiol.

Chromate reduction by chromium-resistant bacteria isolated from soils contaminated with dichromate

J. Environ. Qual.

Uptake of chromium by Aspergillus foetidus

J. Mater. Cycles Waste Manag.

Chromate efflux by means of the chrA chromate resistance protein from Pseudomonas aeruginosa

J. Bacteriol.

Chromate resistance and reduction in Pseudomonas fluorescence strain LB300

Arch. Microbiol.

Original article
Bioreduction of chromium (VI) by Bacillus sp. isolated from soils of iron mineral area