Bioremediation is an efficient strategy for cleaning up sites contaminated with organic pollutants. In this study, we evaluated the effectiveness of monitored natural attenuation, bioenrichment, and bioaugmentation using a consortium of three actinomycetes strains in remediating two distinct typical Brazilian soils from the Atlantic Forest and Cerrado biomes that were contaminated with crude oil, with or without the addition of NaCl. Microcosms were used to simulate bioremediation treatments over a 120-day period. During this period, we monitored total petroleum hydrocarbons (TPHs) and n-alkanes degradation and changes in bacterial communities. Over time, we found the degradation rate of n-alkanes was higher than TPH in both soils, independent of the treatment used. In fact, our data show that the total bacterial community in the soils was mainly affected by the experimental period of time, while the type of bioremediation treatment used was the main factor influencing the actinomycetes populations in both soils. Based on these data, we conclude that monitored natural attenuation is the best strategy for remediation of the two tropical soils studied, with or without salt addition. 1. Introduction The high demand for and use of petroleum and its derivatives worldwide has made petroleum hydrocarbon contamination a global problem with serious health and environmental consequences [1–3]. Contamination of soil and groundwater with petroleum compounds is frequently observed, necessitating the development of innovative technologies for remediation [4, 5]. Bioremediation is an efficient and environmentally friendly technology for long-term restoration of sites contaminated with petroleum hydrocarbons and derivatives [5, 6]. Several studies have focused on the composition of naturally occurring microbial populations that contribute to biodegradation of petroleum and its derivatives in different environments [7–10]. Monitored natural attenuation (MNA) uses the ability of the soil intrinsic microbial community to degrade the contaminant. In cases where enhancement of the soil microbial community is deemed necessary, either bioaugmentation or bioenrichment is used. Bioaugmentation relies upon pollutant-degrading microorganisms found in the contaminated site, whereas in bioenrichment the microorganisms are exogenous [11, 12]. Regardless, studies of both approaches have demonstrated that the degrading organisms are not maintained in the contaminated environment after introduction [13, 14]. Therefore, molecular methods that rapidly survey the microbial community
References
[1]
X. Zhu, A. D. Venosa, and M. T. Suidan, “Literature review on the use of commercial bioremediation agents for cleanup of oil-contaminated estuarine environments,” EPA/600/R-04/075, 2004.
[2]
M. N. P. F. S. Couto, E. Monteiro, and M. T. S. D. Vasconcelos, “Mesocosm trials of bioremediation of contaminated soil of a petroleum refinery: comparison of natural attenuation, biostimulation and bioaugmentation,” Environmental Science and Pollution Research, vol. 17, no. 7, pp. 1339–1346, 2010.
[3]
M. Tyagi, M. M. da Fonseca, and C. C. de Carvalho, “Bioaugmentation and biostimulation strategies to improve the effectiveness of bioremediation processes,” Biodegradation, vol. 22, no. 2, pp. 231–241, 2011.
[4]
L. M. Whang, P. W. G. Liu, C. C. Ma, and S. S. Cheng, “Application of biosurfactants, rhamnolipid, and surfactin, for enhanced biodegradation of diesel-contaminated water and soil,” Journal of Hazardous Materials, vol. 151, no. 1, pp. 155–163, 2008.
[5]
T. C. Lin, P. T. Pan, and S. S. Cheng, “Ex situ bioremediation of oil-contaminated soil,” Journal of Hazardous Materials, vol. 176, no. 1-3, pp. 27–34, 2010.
[6]
T. C. Lin, C. C. Young, M. J. Ho et al., “Characterization of floating activity of indigenous diesel-assimilating bacterial isolates,” Journal of Bioscience and Bioengineering, vol. 99, no. 5, pp. 466–472, 2005.
[7]
F. M. Bento, F. A. O. Camargo, B. C. Okeke, and W. T. Frankenberger, “Comparative bioremediation of soils contaminated with diesel oil by natural attenuation, biostimulation and bioaugmentation,” Bioresource Technology, vol. 96, no. 9, pp. 1049–1055, 2005.
[8]
D. Juck, T. Charles, L. G. Whyte, and C. W. Greer, “Polyphasic microbial community analysis of petroleum hydrocarbon-contaminated soils from two northern Canadian communities,” FEMS Microbiology Ecology, vol. 33, no. 3, pp. 241–249, 2000.
[9]
R. Margesin, D. Labbé, F. Schinner, C. W. Greer, and L. G. Whyte, “Characterization of hydrocarbon-degrading microbial populations in contaminated and pristine Alpine soils,” Applied and Environmental Microbiology, vol. 69, no. 6, pp. 3085–3092, 2003.
[10]
N. Hamamura, S. H. Olson, D. M. Ward, and W. P. Inskeep, “Microbial population dynamics associated with crude-oil biodegradation in diverse soils,” Applied and Environmental Microbiology, vol. 72, no. 9, pp. 6316–6324, 2006.
[11]
M. A. Providenti, H. Lee, and J. T. Trevors, “Selected factors limiting the microbial degradation of recalcitrant compounds,” Journal of Industrial Microbiology, vol. 12, no. 6, pp. 379–395, 1993.
[12]
M. Romantschuk, I. Sarand, T. Pet？nen et al., “Means to improve the effect of in situ bioremediation of contaminated soil: an overview of novel approaches,” Environmental Pollution, vol. 107, no. 2, pp. 179–185, 2000.
[13]
A. Backman, N. Maraha, and J. K. Jansson, “Impact of temperature on the physiological status of a potential bioremediation inoculant, Arthrobacter chlorophenolicus A6,” Applied and Environmental Microbiology, vol. 70, no. 5, pp. 2952–2958, 2004.
[14]
S. A. Huws, A. J. McBain, and P. Gilbert, “Protozoan grazing and its impact upon population dynamics in biofilm communities,” Journal of Applied Microbiology, vol. 98, no. 1, pp. 238–244, 2005.
[15]
J. D. Van Elsas and F. G. H. Boersma, “A review of molecular methods to study the microbiota of soil and the mycosphere,” European Journal of Soil biology, vol. 47, no. 2, pp. 77–87, 2011.
[16]
L. Ciric, J. C. Philp, and A. S. Whiteley, “Hydrocarbon utilization within a diesel-degrading bacterial consortium,” FEMS Microbiology Letters, vol. 303, no. 2, pp. 116–122, 2010.
[17]
K. H. Baek, B. D. Yoon, B. H. Kim et al., “Monitoring of microbial diversity and activity during bioremediation of crude oil-contaminated soil with different treatments,” Journal of Microbiology and Biotechnology, vol. 17, no. 1, pp. 67–73, 2007.
[18]
Y. S. Kang, Y. J. Park, J. Jung, and W. Park, “Inhibitory effect of aged petroleum hydrocarbons on the survival of inoculated microorganism in a crude-oil-contaminated site,” Journal of Microbiology and Biotechnology, vol. 19, no. 12, pp. 1672–1678, 2009.
[19]
V. M. Alvarez, S. C. C. Dos Santos, R. D. C. Casella, R. L. Vital, G. V. Sebastin, and L. Seldin, “Bioremediation potential of a tropical soil contaminated with a mixture of crude oil and production water,” Journal of Microbiology and Biotechnology, vol. 18, no. 12, pp. 1966–1974, 2008.
[20]
EPA 8015D, “Nonhalogenated Organics using GC/FID,” EPA, Revision 4, 2003.
[21]
EPA 8015C, “Nonhalogenated Organics using GC/FID,” EPA, Revision 3, 2000.
[22]
H. P. Caputo, “Propriedades das partículas sólidas do solo,” in Mecanica dos Solos e Suas Aplica？？es, pp. 23–39, Livros Técnicos e Científicos Editora S.A., Rio de Janeiro, Brasil, 1973.
[23]
L. Seldin and D. Dubnau, “Deoxyribonucleic acid homology among Bacillus polymyxa, Bacillus macerans, Bacillus azotofixans, and other nitrogen-fixing Bacillus strains,” International Journal of Systematic Bacteriology, vol. 35, no. 2, pp. 151–154, 1985.
[24]
H. Heuer and K. Smalla, “Application of denaturing gradient gel electrophoresis and temperature gradient gel electrophoresis for studying soil microbial communities,” in Modern Soil Microbiology, J. D. van Elsas, E. M. H. Wellington, and J. T. Trevors, Eds., pp. 353–373, J. Marcel Dekker, New York, NY, USA, 1997.
[25]
U. Nübel, B. Engelen, A. Felsre et al., “Sequence heterogeneities of genes encoding 16S rRNAs in Paenibacillus polymyxa detected by temperature gradient gel electrophoresis,” Journal of Bacteriology, vol. 178, no. 19, pp. 5636–5643, 1996.
[26]
S. El Fantroussi and S. N. Agathos, “Is bioaugmentation a feasible strategy for pollutant removal and site remediation?” Current Opinion in Microbiology, vol. 8, no. 3, pp. 268–275, 2005.
[27]
T. J. Gentry, K. L. Josephson, and I. L. Pepper, “Functional establishment of introduced chlorobenzoate degraders following bioaugmentation with newly activated soil: Enhanced contaminant remediation via activated soil bioaugmentation,” Biodegradation, vol. 15, no. 1, pp. 67–75, 2004.
[28]
N. Sood, S. Patle, and B. Lal, “Bioremediation of acidic oily sludge-contaminated soil by the novel yeast strain Candida digboiensis TERI ASN6,” Environmental Science and Pollution Research, vol. 17, no. 3, pp. 603–610, 2010.
[29]
M. Arensk？tter, D. Br？ker, and A. Steinbüchel, “Biology of the metabolically diverse genus Gordonia,” Applied and Environmental Microbiology, vol. 70, no. 6, pp. 3195–3204, 2004.
[30]
S. J. Lu, H. Q. Wang, and Z. H. Yao, “Isolation and characterization of gasoline-degrading bacteria from gas station leaking-contaminated soils,” Journal of Environmental Sciences, vol. 18, no. 5, pp. 969–972, 2006.
[31]
K. Przybulewska, A. Wieczorek, A. Nowak, and M. Pochrzaszcz, “The isolation of microorganisms capable of phenol degradation,” Polish Journal of Microbiology, vol. 55, no. 1, pp. 63–67, 2006.
[32]
P. Quatrini, G. Scaglione, C. De Pasquale, S. Riela, and A. M. Puglia, “Isolation of Gram-positive n-alkane degraders from a hydrocarbon- contaminated Mediterranean shoreline,” Journal of Applied Microbiology, vol. 104, no. 1, pp. 251–259, 2008.
[33]
X. Zhuang, Z. Han, Z. Bai, G. Zhuang, and H. Shim, “Progress in decontamination by halophilic microorganisms in saline wastewater and soil,” Environmental Pollution, vol. 158, no. 5, pp. 1119–1126, 2010.
[34]
R. Piskonen, M. Nyyss？nen, T. Rajam？ki, and M. It？vaara, “Monitoring of accelerated naphthalene-biodegradation in a bioaugmented soil slurry,” Biodegradation, vol. 16, no. 2, pp. 127–134, 2005.
[35]
L. A. I. De Azeredo, C. D. Da Cunha, A. S. Rosado, et al., “New group-specific 16S rDNA primers for monitoring foaming mycolata during saline waste-water treatment,” Biotechnology Letters, vol. 28, no. 6, pp. 447–453, 2006.
[36]
P. L. Bjerg, N. Tuxen, L. A. Reitzel, H. J. Albrechtsen, and P. Kjeldsen, “Natural attenuation processes in landfill leachate plumes at three Danish sites,” Ground Water.
[37]
K. S. J？rgensen, J. M. Salminen, and K. Bj？rkl？f, “Monitored natural attenuation,” Methods in Molecular Biology (Clifton, N.J.), vol. 599, pp. 217–233, 2010.
