Biostimulation of some Fungal Strains for the Degradation of Atrazine Contaminated Soil
Biostimulatory effects of cow dung on some fungal biodegradation of atrazine. This work was designed to investigate the effect of using a biostimulant (cow dung) on some fungal strains for the possible degradation of atrazine contaminated soil. The physicochemical characteristics of the soil and cow dung were determined using standard methods. The effects of pre and post biostimulation of fungal species were carried out using enumeration techniques. Fungal strains such as Trichoderma harzianum and Aspergillus niger were identified based on macroscopic and microscopic identification. Atrazine degradation was detected by assaying the enzymes involved in the degradation and its metabolites using GC-MS techniques. The results of the soil physicochemical characteristics showed slightly acidic pH (6.7±0.99), moderate calcium (6.3±0.19 Cmol/kg), high magnesium (5.10±0.38 Cmol/kg), moderate potassium (0.48±0.02 Cmol/kg, low sodium (0.15±0.01 Cmol/kg), moderately low nitrogen (0.16±0.01g/kg), moderate phosphorus (12.22±1.45 g/kg), high O.C(15.38±0.05 g/kg) were obtained respectively. The mineral elements content of the cow dung were nitrogen (15.5 mg/g), phosphorus (10.89 mg/g), calcium (2.03 mg/g), potassium (0.57 mg/k and pH (6.9). It was observed that there was a significant difference (P <0.05) between the means of the treatment group compared to the control. From the results a consortium of microorganism gave the highest microbial population in all the groups, with the values of 9.00X10 5 ±44096 and 8.5X10 6 ±45092 at 1% atrazine, 1.80X10 6 ±76376 and 1.70X10 7 ±88192 at 3% atrazine and 2.7 X10 6 ±86602 and 2.55 X 10 7 ±90185 at 5% atrazine for total fungal count pre and post respectively. From the study, the biostimulant (cow dung) was capable of enhancing microbial growth and activity. Hence, Trichoderma harzianum and Aspergillus niger were efficient in bioremediation of atrazine contaminated soil.
