Ability of Fungi, Isolated from Nsukka Peppers and Garden-Egg Plant Rhizospheres, to Solubilize Phosphate and Tolerate Cadmium

C. E. Onyia¹, C. U. Anyawu², M. N. Ikegbunam^3*

¹Biotechnology Centre, University of Nigeria, Nsukka, Nigeria.
²Department of Microbiology, University of Nigeria, Nsukka, Nigeria.
³Department of Pharmaceutical Microbiology and Biotechnology, Nnamdi Azikiwe University, Awka, Nigeria.

DOI: 10.4236/aim.2015.57051                

Abstract

Fungi were isolated from the rhizosphere of pepper and garden-egg plants, with the aim of solubilizing the insoluble phosphate, identifying the most potent isolate from each rhizosphere and testing their tolerance to cadmium metal. The fungi isolates were obtained from the rhizosphere of pepper and garden-egg plants, using PVK agar and NBRIP-BPB broth culture to determine the quantity of phosphate solubilized. From the spectrophotometric readings, isolates GF1 (Penicillium spp) and PF7 (Aspergillus niger) were identified as most potent isolates. Various concentrations of cadmium (100, 50, 10 and 1 μg/ml) were added to the broth containing different isolates for tolerance determination and a control group for different isolates were also obtained. At four-day interval, a quantity of phosphates solubilized at different concentrations of cadmium and control were recorded. The quantity solubilized in 100, 50, 10 and 1 μg/ml treatment groups increased progressively from Day 4 to Day 12 in both isolates, with a sharp increase observed in isolate GF1. The tolerance of GF1 to cadmium showed that there was no significant difference (P < 0.05) in quantity solubilized in the control group when compared with Day 8 and Day 12 of 1 μg/ml concentration of cadmium metal, except at Day 4 which may be as a result of acclimatization. The quantity solubilized for PF7 at control when compared with 1, 10, 50 and 100 μg/ml differed significantly although there were higher quantity of phosphates solubilized when compared with GF1 and other results obtained from most published works. Our results suggested that these two isolates could be used for phosphate solubilization in cadmium metal environment though GF1 tolerates more than PF7, and could be employed for bioremediation of cadmium heavy metals.

Keywords

Fungi, Pepper, Garden Egg, Phoshate and Cadmium

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Akintokun, A.K., Akande, P.O., Popoola, T.O.S. and Babalola, A.O. (2007) Solubilization of Insoluble Phosphate by Organic Acid-Producing Fungi Isolated from Nigerian Soil. International Journal of Soil Science, 2, 301-307. http://dx.doi.org/10.3923/ijss.2007.301.307
[2]	Khan, M.S., Zaidi, A. and Wani, P.A. (2007) Role of Phosphate-Solubilizing Microorganisms in Sustainable Agriculture—A Review. Agronomy for Sustainable Development, 27, 29-43. http://dx.doi.org/10.1051/agro:2006011
[3]	Achal, V., Sudhakara, R.M. and Savan, V.V. (2007) Phosphate Solubilization by a Wild Type Strain and UV-Induced Mutants of Aspergillus tubingensis. Journal of Soil Biology and Biochemistry, 39, 695-699. http://dx.doi.org/10.1016/j.soilbio.2006.09.003
[4]	Richa, G., Khosla, B. and Reddy, M.S. (2007) Improvement of Maize Plant Growth by Phosphate Solubilizing Fungi in Rock Phosphate Amended Soils. World Journal of Agricultural Sciences, 3, 481-484.
[5]	Aadarsh, P., Deepa, V., Murthy, P.B., Deecaramna, M., Sridhar, R. and Dhandapani, P. (2011) Insoluble Phosphate Solubilization by Bacterial Strains Isolated from Rice Rhizosphere Soils from Southern India. International Journal of Soil Science, 6, 134-141. http://dx.doi.org/10.3923/ijss.2011.134.141
[6]	Nanda, S. and Abraham, J. (2011) Impact of Heavy Metals on the Rhizosphere Microflora of Jatropha multifida and Their Effective Remediation. African Journal of Biotechnology, 10, 11948-11955.
[7]	Leyval, C., Turnau, K. and Haselwandter, K. (1997) Effect of Heavy Metal Pollution on Mycorrhizal Colonization and Function: Physiological, Ecological and Applied Aspects. Mycorrhizal, 7, 139-153. http://dx.doi.org/10.1007/s005720050174
[8]	Wang, H., Kimberley, M.O. and Schlegelmilch, M. (2001) Biosolids Derived Nitrogen Mineralization and Transformation in Forest Soils. Journal of Environmental Quality, 32, 1851-1856. http://dx.doi.org/10.2134/jeq2003.1851
[9]	Ezzouhri, L., Castro, E., Moya, M., Espinola, F. and Lairini, K. (2009) Heavy Metal Tolerance of Filamentous Fungi Isolated from Polluted Sites in Tangier, Morocco. African Journal of Microbiology Research, 3, 35-48.
[10]	Hassen, A., Saidi, N., Cherif, M. and Boudabous, A. (1998) Resistance of Environmental Bacteria to Heavy Metals. Bioresources and Technology, 64, 7-15. http://dx.doi.org/10.1016/S0960-8524(97)00161-2
[11]	Gavrilesca, M. (2004) Removal of Heavy Metals from the Environment by Biosorption. Engineering in Life Sciences, 4, 219-232. http://dx.doi.org/10.1002/elsc.200420026
[12]	Baldrian, P. (2003) Interactions of Heavy Metals with White-Rot Fungi. Enzyme and Microbiology Technology, 32, 78-91. http://dx.doi.org/10.1016/S0141-0229(02)00245-4
[13]	Antoun, H. and Prevost, D. (2006) Ecology of Plant Growth Promoting Rhizobacteria. In: Siddiqui, Z.A., Ed., PGPR: Biocontrol and Biofertilization, Springer, Dordrecht, 1-38. http://dx.doi.org/10.1007/1-4020-4152-7_1
[14]	Pikovskaya, R.I. (1948) Mobilization of Phosphorus in Soil Connection with the Vital Activity of Some Microbial Species. Microbiology, 17, 362-370.
[15]	Qurban, A.P., Radziah, O., Zaharah, A.R., Sariah, M. and Mohd, R.I. (2012) Isolation and Characterization of Phosphate-Solubilizing Bacteria from Aerobic Rice. African Journal of Biotechnology, 11, 2711-2719.
[16]	Nautiyal, C.S. (1999) An Efficient Microbiological Growth Medium for Screening Phosphate Solubilizing Microorganisms. Federation of European Microbiological Societies (FEMS), 170, 265-270. http://dx.doi.org/10.1111/j.1574-6968.1999.tb13383.x
[17]	David, E., Stephen, D., Helen, A., Rosemary, H. and Robyn, B. (2007) Descriptions of Medical Fungi. Second Edition, National Library of Australia Cataloguing, Canberra.
[18]	Mohamed, A.H., Mohamed, M.G., Omima, A.E. and Asmaa, M.A. (2009) Evaluation and Optimization of Rock Phosphate and Tri-Calcium Phosphate Solubilization by Soil Fungi. Egypt Journal of Experimental Biology, 5, 75-84.
[19]	Bolan, N.S., Naidu, R. and Mahimairaja, S. (1995) Influence of Low Molecular Organic Acids on Solubilization of Phosphorus in Soils. Journal of Biology and Fertility Soils, 18, 311-319. http://dx.doi.org/10.1007/BF00570634
[20]	Mergeay, M., Monchy, S., Vallaeys, T., Auquier, V., Benotmane, A., Bertin, P., Taghavi, S., Dunn, J., Van der Lelie, D. and Wattiez, R. (2003) Ralstonia metallidurans, a Bacterium Specially Adapted to Toxic Metals: Toward a Catalogue of Metal-Responsive Genes. FEMS Microbiology Reviews, 27, 385-410. http://dx.doi.org/10.1016/S0168-6445(03)00045-7
[21]	Kermasha, S., Pellerin, F., Rovel, B., Goetghebeur, M. and Metche, M. (1993) Purification and Characterization of Copper-Metallothioneins from Aspergillus niger. Bioscience, Biotechnology and Biochemistry, 57, 1420-1423. http://dx.doi.org/10.1271/bbb.57.1420