Paraquat biodegradation in peat soil by fungi and yeast
2004
Martani, E.%(Universitas Gajah Mada, Yogyakarta (Indonesia). Fakultas Pertanian))
This experiment was done to study the ability of fungi and yeast to accelerate paraquat degradation in peat soil. Hopefully, degradation acceleration can minimize the impact of this herbicide to non target organism. Two fungal and three yeast isolates, i.e. Penicillium sp. JH-3, Aspergillus sp. FF-12, Rhodotorula sp. KH1, Cryptococcus sp. KF-1 and Sporobolomyces sp. KF-9, were selected based on their ability to degrade paraquat in a synthetic medium. Sterilized and non-sterilized of fibric and saphric peat soils were used for examining single and mixed microbial cultures to degrade paraquat. Paraquat residue and microbial population were measured periodically using spectrophotometric method and total viable count, respectively. Paraquat could not be degraded in non-inoculated peat soil; which reflected that chemical process was not influence its existence in peat soil. However, inoculation of single and mixed of microorganisms enhanced biodegradation of paraquat, which means that biological agents were required to degrade this chemical. Biodegradation of paraquat in soils inoculated with mixed cultures was slightly higher than those of single culture. The acceleration of biodegradation was depending on the inoculated species and soil type. Paraquat degradation was greater in fibric than in saphric peat soil. Although paraquat was degraded, no significant growth of fungi nor yeast in the soil. It might be due to the relatively low concentration of paraquat for detectable growth of microorganisms or specific mechanisms in degradation pathway. These results give prospective information in minimizing paraquat impact to soil environment and non-target organisms.
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