Bioremediation of lead contaminated soil with Rhodobacter sphaeroides
Introduction
Lead (Pb) contamination in soil is one of the major public concerns in recent years, as Pb can accumulate in plant or human body leading to irreversible damage to human health, especially for children. Such damage includes impaired development, reduced intelligence, short-term memory loss, disabilities in learning and coordination problems, and risk of cardiovascular disease (Dixit et al., 2015). Heavy metal contamination in soil can be remediated through various mobilization and immobilization techniques (Fan et al., 2012). Compared with physicochemical methods, biotechnological approaches are gaining increasing prominence in the remediation of a variety of environmental matrices because they are cost effective, environmentally friendly, and are associated with fewer side effects. They have therefore emerged as potentially useful alternative technologies for restoring contaminated sites and removing contaminants from the environment (Dhankhar and Hooda, 2011, Mani and Kumar, 2013, Merugu et al. 2014, Aryal and Liakopoulou-Kyriakides, 2015, Dixit et al., 2015, Fonti et al., 2015).
A wide variety of microorganisms (fungi, algae, bacteria, etc.) are already used as tools for heavy metal bioremediation, whose mechanisms mainly include valence transformation, volatilization and extracellular chemical precipitation (Wu et al., 2010, Marques et al., 2011). Rhodobacter sphaeroides is a Gram-negative, phototropic purple non-sulfur bacterium exhibiting several metabolic pathways depending on the growth conditions (Calvano et al., 2014). This versatile bacterium has drawn considerable attention in energy and environment researches; for example, it has been reported to be important in hydrogen production and photobioelectrochemical fuel cell development (Zhu et al., 2002, Rosenbaum et al., 2005, Hakobyan et al., 2012). In addition, it has been widely applied to treat wastewater because of its strong survivability under abiotic stress conditions and high tolerance to carbon starvation (Kanno et al., 2014), herbicides (Zhang et al., 2012), salt (Panwichian et al., 2010b), heavy metals (Buccolieri et al., 2006, Giotta et al., 2006, Panwichian et al., 2011, Volpicella et al., 2014), and organic and eutrophication (Nagadomi et al., 2000, Kim et al., 2004, Kantachote et al., 2005, Takeno et al., 2005, Madukasi et al., 2010, Merugu et al. 2014). The R. sphaeroides strains had been used to degrade various contaminants from soil and sediment mud, such as phosphorus, atrazine, salts and radionuclide (cesium), whilst the removal efficiency, impacting factors and mechanisms of which had also been discussed (Takeno et al., 1999, Du et al., 2011, Panwichian et al., 2012, Sasaki et al., 2012a, Sasaki et al., 2012b). However, the studies concentrated on bioremediation of heavy metal in soil using R. sphaeroides has rarely been reported. Fan et al. (2012) and Panwichian et al. (2012) had used the strain to remove heavy metals from soil and sediment mud, respectively, and plant growth experiments were performed to evaluate the phytotoxicity after bioremediation. But, the bioremediation mechanism for heavy metal contaminated soil has not been well understood until now.
R. sphaeroides had been employed to remedy cadmium (Cd) contaminated soil in our former research (Fan et al., 2012), which concluded that the bacterium could redistribute the geo-speciation of Cd and reduce the Cd phytoavailability in amended soils. In addition, it was noticed that the geo-speciation of Pb also changed remarkably during the bioremediation process. Thus, in this paper, we further investigate the optimum culturing condition of R. sphaeroides and its tolerance to Pb. The remediation efficiency and mechanisms are also discussed in details.
Section snippets
Isolation and identification of R. sphaeroides
The strain isolated from the oil field injection water in DaQing was identified as R. sphaeroides (Fan et al., 2012). Postgate C liquid medium was selected as the culture medium for R. sphaeroides (Postgate, 1979). The culture medium was prepared with oil field injection water. Optical density at 420 nm (OD420) measured by an ultraviolet–visible spectrophotometer (UV-754) was examined for cell counting because a significant positive correlation (r = 0.9850, p < 0.01) was obtained between OD420
Optimum culturing conditions and Pb tolerance of R. sphaeroides
Influences of temperature, pH, and inoculum size on the growth of R. sphaeroides are shown in Fig. 1a–c, respectively. It was found that the influences of temperature, pH, and inoculum size on the growth of R. sphaeroides had similar curves; they increased at first and then decreased over time. The maximum biomass was obtained at T = 35 °C, pH = 7, and inoculum size = 2 × 108 mL−1, but the high biomass was also observed at T = 30 °C. Thus, the optimum temperature was 30–35 °C and the optimum pH
Conclusions
In present study, R. sphaeroides was used for bioremediation of Pb contaminated soils. Optimum culturing conditions of the strain were firstly investigated, and results showed that the optimum culturing conditions of R. sphaeroides were pH = 7, T = 30–35 °C, with the inoculum size of 2 × 108 mL−1. Then, the bioremediation experiments were conducted under these conditions. It was found that, during soils bioremediation, R. sphaeroides did not decrease the total content of Pb in soil but could
Acknowledgments
This work was supported by the National Natural Science Foundation of China (51178019, 51290283 and 51378041), Beijing Natural Science Foundation (8142027), Specialized Research Fund for the Doctoral Program of Higher Education (20131102110035), and Major Science and Technology Program for Water Pollution Control and Treatment of China (2012ZX07501001).
References (53)
- et al.
Remediation of heavy metal contaminated soil washing residue with amino polycarboxylic acids
J. Hazard. Mater
(2010) - et al.
Microbial synthesis of semiconductor lead sulfide nanoparticles using immobilized Rhodobacter sphaeroides
Mater. Lett.
(2009) - et al.
Bioremediation of cadmium by growing Rhodobacter sphaeroides: kinetic characteristic and mechanism studies
Bioresour. Technol.
(2008) - et al.
Simulation study of atrazine-contaminated soil biodegradation by strain W16
Procedia Environ. Sci.
(2011) - et al.
Phytoavailability and geospeciation of cadmium in contaminated soil remediated by Rhodobacter sphaeroides
Chemosphere
(2012) - et al.
Bioremediation of contaminated marine sediments can enhance metal mobility due to changes of bacterial diversity
Water Res.
(2015) - et al.
Heavy metal ion influence on the photosynthetic growth of Rhodobacter sphaeroides
Chemosphere
(2006) - et al.
Bio-hydrogen production and the F0F1-ATPase activity of Rhodobacter sphaeroides: effects of various heavy metal ions
Int. J. Hydrogen Energy
(2012) - et al.
In situ stabilization of cadmium-, lead-, and zinc-contaminated soil using various amendments
Chemosphere
(2009) - et al.
Concentrations and chemical speciations of Cu, Zn, Pb and Cr of urban soils in Nanjing, China
Geodermia
(2003)
Removal of phosphorus from oyster farm mud sediment using a photosynthetic bacterium, Rhodobacter sphaeroides IL106
J. Biosci. Bioeng.
A critical review on the bio-removal of hazardous heavy metals from contaminated soils: issues, progress, eco-environmental concerns and opportunities
J. Hazard. Mater.
Oxidative stress response in atrazine-degrading bacteria exposed to atrazine
J. Hazard. Mater.
Hydrogen production as a novel process of wastewater treatment—studies on tofu wastewater with entrapped R. sphaeroides and mutagenesis
Int. J. Hydrogen Energy
Bioremoval of heavy metals by bacterial biomass
Environ. Monit. Assess.
Texture and geochemistry of the sediments of a tropical mangrove ecosystem, southwest coast of India
Environ. Geol.
Biological synthesis of size-controlled cadmium sulfide nanoparticles using immobilized Rhodobacter sphaeroides
Nanoscale Res. Lett.
Toxic effects of Pb2+, Cd2+ and Cr(Ⅵ) on inhibition of Rhodobacter sphaeroides growth
Chin. J. Appl. Environ. Biol.
Study on transformation and removal of the heavy metal cadmium by Rhodobacter sphaeroides
Acta Sci. Circumstantiae
Studies on removal and transformation mechanism of lead by Rhodobacter sphaeroides
Acta Sci. Circumstantiae
Testing the photosynthetic bacterium Rhodobacter sphaeroides as heavy metal removal tool
Ann. Chim.
The lipidome of the photosynthetic bacterium Rhodobacter sphaeroides R26 is affected by cobalt and chromate ions stress
Biometals Int. J. Role Metal Ions Biol. Biochem. Med.
Mobility and adsorption capacity of Pb and Zn in a polluted soil from a road environment: laboratory batch experiments
Environ. Technol.
Fungal biosorption–an alternative to meet the challenges of heavy metal pollution in aqueous solutions
Environ. Technol.
Bioremediation of heavy metals from soil and aquatic environment: an overview of principles and criteria of fundamental processes
Sustainability
Distribution of Cd, Pb, Zn and Cu and their chemical speciations in soils from a peri-smelter area in northeast China
Environ. Geol.
Cited by (95)
Sulfur source promotes the biosorption and bioprecipitation of Cd in purple non-sulfur bacteria
2024, International Biodeterioration and BiodegradationInsight into adsorption of Pb(II) with wild resistant bacteria TJ6 immobilized on biochar composite: Roles of bacterial cell and biochar
2024, Separation and Purification TechnologyA novel photoanaerobic process as a feasible alternative to the traditional aerobic treatment of refinery wastewater
2023, Journal of Water Process EngineeringLead pollution: Impact on environment and human health and approach for a sustainable solution
2023, Environmental Chemistry and Ecotoxicology