Bioremediation of Heavy Metals in the Soil by Pseudomonas aeruginosa and Trichoderma harzianum Using Solanum lycopersicum as Test Plant

Abstract

This study determined the heavy metal concentrations of contaminated stream water and assessed the heavy metal contents of pre- and post-cropped sterilized soil. It also determined the the heavy metal uptake of the S. lycopersicum plant. This was with a view to assessing the potential of Pseudomonas aeruginosa and Trichoderma harzianum for transforming heavy metals in heavy metal contaminated stream water. Experimental pots containing 3000 g of sterilized soil was used for this experiment whereby 60 sample pots were used with various treatments in this study. Solanum lycopersicum seeds were raised in the nursery for a period of 3 weeks and treatments applied just before transplanting into the experimental pots. The plants were left for a week so as to be established properly and overcome transplanting shock before watering with the contaminated stream water. Heavy metal analysis using Atomic Absorption Spectroscopy (AAS) method was carried out on the contaminated stream water to determine the amount of heavy metal in the stream water before the commencement of the experiment. The contaminated stream water was applied to the pots in measured quantities; 0, 5 and 10%. Pre and post soil heavy metal analysis were carried out on the soil samples. At harvest, plant tissues were analysed for heavy metals using AAS method. The results showed that heavy metals were present in high concentration in the stream water sample. The values of the heavy metals in the stream water sample used for watering were Iron – 138.15 mg/L, Zinc – 68.4 mg/L, Lead – 7.89 mg/L and Copper – 8.98 mg/L. Heavy metal analysis of the soil and all the treatments revealed that treatments with P. aeruginosa inoculation had the lowest level of Iron, Copper, Zinc and Lead followed by treatments inoculated with T. harzianum. The study concluded that the use of contaminated stream water for irrigation could be a potential source of heavy metals in tomato. However, inoculation of microorganisms for the treatment of the heavy metal contaminated sites was effective Phytoremediation,for increased health, growth and yield of tomato fruits.