Bioremediation perspectives of agricultural soil from Tulancingo Valley, México, with Trichoderma sp. native to degrade atrazine. Tropical and Subtropical Agroecosystems

The objective of this study was to show an in vitro bioremediation methodology for atrazine-contaminated soils through the use of local strains of native fungi isolated from the Phaseolus vulgaris L rhizosphere present in cultivable soils as well as to evaluate its resistance and capacity for atrazine degradation. A Trichoderma sp. species was identified in three cultivable soils from the Tulancingo Hidalgo, México region (contaminated with and without atrazine), which resisted atrazine concentrations of 10,000 mg L-1. Tests showed that the strain grows exponentially in atrazine-contaminated soil over a range of 105-106 CFU g-1 in 15 days using atrazine as the only carbon and nitrogen source, while the control and witress showed a decrease of 100-103 UFC g-1 in the same period of time. For the atrazine degradation experiments, a treatment of the application of Trichoderma (104 - 105 CFU mL-1) was applied to sterilized and non-sterilized soil contaminated with 500 mg Kg-1 of atrazine, evaluated at four time intervals (5, 10, 20 and 40 days). Statistical differences were found (?=0.050, Tukey) among treatments with the fungi and the test days. The native Trichoderma strain degraded 89% of the atrazine in 40 days. It showed that it is viable and cultivable in soil bioremediation.