Advertisement

Environmental Science and Pollution Research

, Volume 17, Issue 2, pp 288–296 | Cite as

Effects of Cd and Pb on soil microbial community structure and activities

  • Sardar Khan
  • Abd El-Latif Hesham
  • Min Qiao
  • Shafiqur Rehman
  • Ji-Zheng He
AREA 1.1 • BEHAVIOR OF CHEMICALS IN SOILS / INTERACTIONS WITH BIOTA • RESEARCH ARTICLE

Abstract

Background, aim, and scope

Soil contamination with heavy metals occurs as a result of both anthropogenic and natural activities. Heavy metals could have long-term hazardous impacts on the health of soil ecosystems and adverse influences on soil biological processes. Soil enzymatic activities are recognized as sensors towards any natural and anthropogenic disturbance occurring in the soil ecosystem. Similarly, microbial biomass carbon (MBC) is also considered as one of the important soil biological activities frequently influenced by heavy metal contamination. The polymerase chain reaction–denaturing gradient gel electrophoresis (DGGE) has recently been used to investigate changes in soil microbial community composition in response to environmental stresses. Soil microbial community structure and activities are difficult to elucidate using single monitoring approach; therefore, for a better insight and complete depiction of the soil microbial situation, different approaches need to be used. This study was conducted in a greenhouse for a period of 12 weeks to evaluate the changes in indigenous microbial community structure and activities in the soil amended with different application rates of Cd, Pb, and Cd/Pb mix. In a field environment, soil is contaminated with single or mixed heavy metals; so that, in this research, we used the selected metals in both single and mixed forms at different application rates and investigated their toxic effects on microbial community structure and activities, using soil enzyme assays, plate counting, and advanced molecular DGGE technique. Soil microbial activities, including acid phosphatase (ACP), urease (URE), and MBC, and microbial community structure were studied.

Materials and methods

A soil sample (0–20 cm) with an unknown history of heavy metal contamination was collected and amended with Cd, Pb, and Cd/Pb mix using the CdSO4 and Pb(NO3)2 solutions at different application rates. The amended soils were incubated in the greenhouse at 25 ± 4°C and 60% water-holding capacity for 12 weeks. During the incubation period, samples were collected from each pot at 0, 2, 9, and 12 weeks for enzyme assays, MBC, numeration of microbes, and DNA extraction. Fumigation–extraction method was used to measure the MBC, while plate counting techniques were used to numerate viable heterotrophic bacteria, fungi, and actinomycetes. Soil DNAs were extracted from the samples and used for DGGE analysis.

Results

ACP, URE, and MBC activities of microbial community were significantly lower (p < 0.05) in the metal-amended samples than those in the control. The enzyme inhibition extent was obvious between different incubation periods and varied as the incubation proceeded, and the highest rate was detected in the samples after 2 weeks. However, the lowest values of ACP and URE activities (35.6% and 36.6% of the control, respectively) were found in the Cd3/Pb3-treated sample after 2 weeks. Similarly, MBC was strongly decreased in both Cd/Pb-amended samples and highest reduction (52.4%) was detected for Cd3/Pb3 treatment. The number of bacteria and actinomycetes were significantly decreased in the heavy metal-amended samples compared to the control, while fungal cells were not significantly different (from 2.3% to 23.87%). In this study, the DGGE profile indicated that the high dose of metal amendment caused a greater change in the number of bands. DGGE banding patterns confirmed that the addition of metals had a significant impact on microbial community structure.

Discussion

In soil ecosystem, heavy metals exhibit toxicological effects on soil microbes which may lead to the decrease of their numbers and activities. This study demonstrated that toxicological effects of heavy metals on soil microbial community structure and activities depend largely on the type and concentration of metal and incubation time. The inhibition extent varied widely among different incubation periods for these enzymes. Furthermore, the rapid inhibition in microbial activities such as ACP, URE, and MBC were observed in the 2 weeks, which should be related to the fact that the microbes were suddenly exposed to heavy metals. The increased inhibition of soil microbial activities is likely to be related to tolerance and adaptation of the microbial community, concentration of pollutants, and mechanisms of heavy metals. The DGGE profile has shown that the structure of the bacterial community changed in amended heavy metal samples. In this research, the microbial community structure was highly affected, consistent with the lower microbial activities in different levels of heavy metals. Furthermore, a great community change in this study, particularly at a high level of contamination, was probably a result of metal toxicity and also unavailability of nutrients because no nutrients were supplied during the whole incubation period.

Conclusions

The added concentrations of heavy metals have changed the soil microbial community structure and activities. The highest inhibitory effects on soil microbial activities were observed at 2 weeks of incubation. The bacteria were more sensitive than actinomycetes and fungi. The DGGE profile indicated that bacterial community structure was changed in the Cd/Pb-amended samples, particularly at high concentrations.

Recommendations and perspectives

The investigation of soil microbial community structure and activities together could give more reliable and accurate information about the toxic effects of heavy metals on soil health.

Keywords

DGGE Enzymatic activity Heavy metals Microbial biomass carbon Microbial community 

Notes

Acknowledgement

This work was financially supported by the Chinese Academy of Sciences (kzcx1-yw-06-03) and the Ministry of Science and Technology (2007CB407301 and 2007CB407304). Mr. Sardar Khan would like to thank the Higher Education Commission, Islamabad, Pakistan for supporting his Ph.D. study.

References

  1. Baum C, Linweber P, Schlichting A (2003) Effects of chemical conditions in re-wetted peats temporal variation in microbial biomass and acid phosphatase activity within the growing season. Appl Soil Ecol 22:167–174CrossRefGoogle Scholar
  2. Bhattacharyya P, Tripathy S, Chakrabarti K, Chakraborty A, Banik P (2008) Fractionation and bioavailability of metals and their impacts on microbial properties in sewage irrigated soil. Chemosphere 72:543–550CrossRefGoogle Scholar
  3. Briuns MR, Kapil S, Oehme FW (2000) Microbial resistance to metals in the environment. Ecotoxicol Environ Saf 45:198–207CrossRefGoogle Scholar
  4. Brookes PC (1995) The use of microbial parameters in monitoring soil pollution. Biol Fertil Soils 19:269–279CrossRefGoogle Scholar
  5. Chen CL, Lio M, Huang CY (2005) Effect of combined pollution by heavy metals on soil enzymatic activities in areas polluted by tailings from Pb–Zn–Ag mine. J Environ Sci 17:637–640Google Scholar
  6. Claudia SG, Werner L, Sabine R (2003) Application of broad-range 16S rRNA PCR amplification and DGGE fingerprinting for detection of tick-infecting bacteria. J Microbiol Methods 52:251–260Google Scholar
  7. Dick RP (1997) Soil enzyme activities as integrative indicators of soil health. In: Pankhurst CE, Doube BM, Gupta VVSR (eds) Biological indicators of soil health. CAB International, New York, pp 121–156Google Scholar
  8. Dick RP, Breakwell DP, Turco RF (1996) Soil enzyme activities and biodiversity measurements and integrative microbial indicators. Methods of assessing soil quality. SSSA special publication 49, Soil Science Society of America, American Society of Agronomy, Madison, WI, pp 247–271Google Scholar
  9. Frostegård Å, Tunlid A, Bååth E (1996) Changes in microbial community structure during long-term incubation in two soils experimentally contaminated with metals. Soil Biol Biochem 28:55–63CrossRefGoogle Scholar
  10. He JZ, Xu ZH, Hughes J (2005) Soil fungal communities in adjacent natural forest and hoop pine plantation ecosystems as revealed by molecular approaches based on 18S rRNA genes. FEMS Microbiol Lett 247:91–100CrossRefGoogle Scholar
  11. He JZ, Xu ZH, Hughes J (2006) Molecular bacterial diversity of a forest soil under different residue management regimes in subtropical Australia. FEMS Microbiol Ecol 55:38–47CrossRefGoogle Scholar
  12. Hinojosa MB, Carreira JA, García-Ruíz R, Dick RP (2004) Soil moisture pre-treatment effects on enzyme activities as indicators of heavy metal-contaminated and reclaimed soils. Soil Biol Biochem 36:1559–1568CrossRefGoogle Scholar
  13. Khan S, Cao Q, Hesham AB, Xia Y, He J (2007) Soil enzymatic activities and microbial community structure with different application rates of Cd and Pb. J Environ Sci 19:834–840CrossRefGoogle Scholar
  14. Khan S, Cao Q, Zheng YM, Huang YZ, Zhu YG (2008) Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China. Environ Pollut 152:686–692CrossRefGoogle Scholar
  15. Kızılkaya R, Bayraklı B (2005) Effects of N-enriched sewage sludge on soil enzyme activities. Appl Soil Ecol 30:192–202CrossRefGoogle Scholar
  16. Kızılkaya R, Aşkın T, Bayraklı B, Sağlam M (2004) Microbiological characteristics of soils contaminated with heavy metals. Eur J Soil Biol 40:95–102CrossRefGoogle Scholar
  17. Lasat MM (2002) Phytoextraction of toxic metals: a review of biological mechanisms. J Environ Qual 31:109–120CrossRefGoogle Scholar
  18. Masto RE, Chhonkar PK, Singh D, Patra AK (2008) Changes in soil quality indicators under long-term sewage irrigation in a sub-tropical environment. Environ Geol. doi: 10.1007/s00254-008-1223-2 Google Scholar
  19. McGrath SP, Zhao FJ, Lombi E (2001) Plant and rhizosphere processes involved in phytoremediation of metal-contaminated soils. Plant Soil 232:207–214CrossRefGoogle Scholar
  20. Mette HN, Neils BR (2002) Denaturing gradient gel electrophoresis (DGGE) approaches to study the diversity of ammonia-oxidizing bacteria. J Microbiol Methods 50:189–203CrossRefGoogle Scholar
  21. Moreels D, Crosson G, Garafola C, Monteleone D, Taghavi S, Fitts JP, Lelie D (2008) Microbial community dynamics in uranium contaminated subsurface sediments under biostimulated conditions with high nitrate and nickel pressure. Environ Sci Pollut Res 15:481–491CrossRefGoogle Scholar
  22. Moreno JL, García C, Hernández T (2003) Toxic effect of cadmium and nickel on soil enzymes and the influence of adding sewage sludge. Eur J Soil Sci 54:377–386CrossRefGoogle Scholar
  23. Moreno JL, Hernández T, Pérez A, García C (2002) Toxicity of cadmium to soil microbial activity: effects of sewage sludge addition to soil on the ecological dose. Appl Soil Ecol 21:149–158CrossRefGoogle Scholar
  24. Muyzer G, Waal de EC, Uitterlinden AG (1993) Profiling of complex microbial populations by denaturing gradient gel electrophoresis analysis of polymerase chain reaction-amplified genes coding for 16S rRNA. Appl Environ Microbiol 59:695–700Google Scholar
  25. Oliveira A, Pampulha ME (2006) Effects of long-term heavy metal contamination on soil microbial characteristics. J Biosci Bioeng 102:157–161CrossRefGoogle Scholar
  26. Pérez-de-Mora A, Burgos P, Madejón E, Cabrera F, Jaeckel P, Scholter M (2006) Microbial community structure and function in a soil contaminated by heavy metals: effects of plant growth and different amendments. Soil Biol Biochem 38:327–341Google Scholar
  27. Shen G, Cao L, Lu Y, Hong J (2005) Influence of phenanthrene on cadmium toxicity to soil enzymes and microbial growth. Environ Sci Pollut Res 12:259–263CrossRefGoogle Scholar
  28. Vance ED, Brookes PC, Jenkinson DS (1987) An extraction method for measuring soil microbial biomass C. Soil Biol Biochem 19:703–707CrossRefGoogle Scholar
  29. Wang YP, Shi YJ, Wang H, Lin Q, Chen XC, Chen YX (2007) The influence of soil heavy metals pollution on soil microbial biomass, enzyme activity, and community composition near a copper smelter. Ecotoxicol Environ Saf 67:75–81CrossRefGoogle Scholar
  30. Wang YP, Li QB, Shi JY, Lin Q, Chen XC, Wu W, Chen YX (2008) Assessment of microbial activity and bacterial community composition in the rhizosphere of a copper accumulator and a non-accumulator. Soil Biol Biochem 40:1167–1177CrossRefGoogle Scholar
  31. Xu Q, Jiang P, Xu Z (2008) Soil microbial functional diversity under intensively managed bamboo plantations in southern China. J Soils Sediments 8:177–183CrossRefGoogle Scholar
  32. Zhang Y, Zhang HW, Su ZC, Zhang CG (2008) Soil microbial characteristics under long-term heavy metal Stress: a case study in Zhangshi wastewater irrigation area, Shenyang. Pedosphere 18:1–10CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Sardar Khan
    • 1
    • 2
  • Abd El-Latif Hesham
    • 3
  • Min Qiao
    • 2
  • Shafiqur Rehman
    • 1
  • Ji-Zheng He
    • 2
  1. 1.Department of Environmental SciencesUniversity of PeshawarPeshawarPakistan
  2. 2.Chinese Academy of Sciences, State Key Laboratory of Urban and Regional EcologyResearch Center for Eco-Environmental SciencesBeijingChina
  3. 3.Genetics Department, Faculty of AgricultureAssiut UniversityAsyutEgypt

Personalised recommendations