Influence of Aged Zinc Oxide Nanoparticles Amended Loam Soil on Nutritional Salts and Arachis Hypogea Rhizosphere Microbial Population"

The  influence of aged zinc oxide nanoparticles amended loam soil on nutritional salts and Arachis hypogearhizosphere microbial population was assessed using standard microbiological methods. The total heterotrophic bacteria counts and abundance at the field and greenhouse exposures at different concentrations were recorded as; 6.54 ± 0.1, 5.50 ± 0.3, 5.30 ± 0.4, and 5.40 ± 0.1 for control, 1000mg/kg, 2000mg/kg and 4000mg/kg respectively for aerobic organism in field. .The total heterotrophic bacteria count for aerobic organisms identified in the spiked loam samples kept in the greenhouse were 7.36 ± 0.03, 5.39 ± 0.6, 5.73 ± 0.2 and 5.54 ± 0.1 for control, 1000mg/kg, 2000mg/kg and 4000mg/kg respectively. For anaerobic organisms in the greenhouse, the total heterotrophic bacteria counts were 6.90 ± 0.1, 6.12 ± 0.3, 5.87 ± 0.1 and 5.67 ± 0.1 for control,1000mg/kg, 2000mg/kg and 4000mg/kg concentrations respectively. For anaerobic organisms in the greenhouse, the total heterotrophic bacteria counts were 7.04 ± 0.1, 5.69 ± 0.3, 5.74 ± 0.1 and 5.45 ± 0.2 for control, 1000mg/kg, 2000mg/kg and 4000mg/kg concentrations respectively.  Probable organisms identified after isolation were members of the genera Corynebacterium, Cellulomonas, Rhizobium, Bacillus, Pseudomonas, Serratia and Citrobacter. The addition of the Zinc oxide nanoparticles led to an increase in the amount of nitrate, sulphate, phosphate and zinc and a significant decrease in the amount of calcium, magnesium and organic matter at both environmental exposures compared to the unspiked loam soil. These differences and change showed the phototoxicity of the nanoparticles