Biodegradation of PCP by the Rhizobacteria Isolated from Pentachlorophenol-tolerant Crop Species

Authors: Avita K. Marihal, K.S. Jagadeesh, Sarita Sinha

Abstract:

Pentachlorophenol (PCP) is a polychlorinated aromatic compound that is widespread in industrial effluents and is considered to be a serious pollutant. Among the variety of industrial effluents encountered, effluents from tanning industry are very important and have a serious pollution potential. PCP is also formed unintentionally in effluents of paper and pulp industries. It is highly persistent in soils and is lethal to a wide variety of beneficial microorganisms and insects, human beings and animals. The natural processes that breakdown toxic chemicals in the environment have become the focus of much attention to develop safe and environmentfriendly deactivation technologies. Microbes and plants are among the most important biological agents that remove and degrade waste materials to enable their recycling in the environment. The present investigation was carried out with the aim of developing a microbial system for bioremediation of PCP polluted soils. A number of plant species were evaluated for their ability to tolerate different concentrations of pentachlorophenol (PCP) in the soil. The experiment was conducted for 30 days under pot culture conditions. The toxic effect of PCP on plants was studied by monitoring seed germination, plant growth and biomass. As the concentration of PCP was increased to 50 ppm, the inhibition of seed germination, plant growth and biomass was also increased. Although PCP had a negative effect on all plant species tested, maize and groundnut showed the maximum tolerance to PCP. Other tolerating crops included wheat, safflower, sunflower, and soybean. From the rhizosphere soil of the tolerant seedlings, as many as twenty seven PCP tolerant bacteria were isolated. From soybean, 8; sunflower, 3; safflower 8; maize 2; groundnut and wheat, 3 each isolates were made. They were screened for their PCP degradation potentials. HPLC analyses of PCP degradation revealed that the isolate MAZ-2 degraded PCP completely. The isolate MAZ-1 was the next best isolate with 90 per cent PCP degradation. These strains hold promise to be used in the bioremediation of PCP polluted soils.

Keywords: Biodegradation, pentachlorophenol, rhizobacteria.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1062176

References:

[1] M.M. Haggblom, Microbial breakdown of halogenated aromatic pesticides and related compounds. FEMS Microbiol. Rev., Vol.30, 1992, pp. 357 -363.
[2] J. Valenzuela, U. Bumann, R. Cespedes, L. Padilla, B. Gonzalez, Degradation of chlorophenols by Alcaligenes eutrophus JMP134 (pJP 4) in bleached kraft mill effluent. Appl. Environ. Microbiol., Vol.63, 1997, pp. 227-232.
[3] Yan He, Jianming Xu, Caixian Tang, Yuping Wu., Facilitation of Pentachlorophenol degradation in the rhizosphere of ryegrass (Lolium perenne L.). Soil Biol. Biochem., Vol.37, 2005, pp, 2017 - 2024.
[4] A. M Ferro, R.C. Sims and B.Bugbee, Hycrest crested wheatgrass accelerates the degradation of Pentachlorophenol in Soil. J. Environ. Qual., Vol. 23, 1994b, pp, 272-279.
[5] Tessa Mills, Barbara Arnold, Sivakumaran, Grant Northcott, Iris Vogeler, Brett Robinson, Cara Norling, Doris Leonil, Phytoremediation and long term site management of soil contaminated with pentachlorophenol (PCP) and heavy metals. J Environ. Manage., Vol. 79, 2006, pp, 232-241.
[6] R.I. Dams, G.I. Paton and K. Killham., Rhizoremediation of pentachlorophenol by Sphingobium chlorophenolicum (ATCC 397233). Chemosphere, Vol 68(5), 2007, pp. 864-870.
[7] J.G. Steiert and R.L. Crawford, Degradation of chlorinated phenols by a pentachlorophenol degrading bacterium. Appl. Environ. Microbiol., Vol. 53, 1987, pp, 907-910.
[8] J. P. Chu and E.J.Kirsch, Metabolism of pentachlorophenol by axenic bacterial culture. Appl. Environ. Microbiol., Vol. 23, 1972, pp. 1033- 1035.
[9] M.M. Haggblom, L.J. Nohynek and M.S. Salkinoja-Salonen, Degradation and O- methylation of chlorinated phenolic compounds by Rhodococcus and Mycobacterium strains. Appl. Environ. Microbiol., Vol.54,1988c, pp. 3043-3052.
[10] L. Saber Diane and R. L. Crawford, Isolation and characterization of Flavobacterium strains that degrade pentachlorophenol. Appl. Environ. Microbiol., Vol. 50, 1985, pp.1512 - 1518.
[11] I.S.Thakur, R. Sharma, S. Shukla, and A.H.Ahmed, Enumeration and enrichment o pentachlorophenol degrading bacterial population of pulp and paper mill in the chemostat. AMI Conference, Jaipur, November 25- 27, 2000, pp. 159.
[12] M.D. Webb, G. Ewbank, J. Perkins, A.J. McCarthy, Metabolism of pentachlorophenol by Saccharomonospora viridis strains isolated from mushroom compost. Soil Biol. Biochem., Vol. 33, 2001, pp.315-321.