Bio stimulation of indigenous microorganisms with Gomeya: a bioremediation technique

Abstract

The burden of heavy metals in the environment can be reduced using organic amendment stimulated bacterial remediation. This study employed cattle manure slurry stimulated bacterial inoculum to treat heavy metals-contaminated soil. Samples of contaminated soil and cattle manure were collected from the area surrounding a steel rolling mill and a commercial animal pen respectively. Bacteria were isolated using pour plate technique; identified using various biochemical tests and screened for resistance to heavy metal salts by incorporating heavy metal salts into agar plates. The contaminated soil and manure slurry were analysed for heavy metals and then sterilised separately. Five kilogram of the sterilised contaminated soil was weighed and mixed with 100g of sterilized cow dung slurry and aseptically packed into plastic nursery bags. Bacterial samples showing high tolerance to heavy metal salts were introduced into the bags singly and as a consortium for bioremediation exercise. Thirty-six bacterial isolates were obtained from the contaminated soil. Chemical analysis revealed that the soil was heavily contaminated especially with lead and chromium with concentrations of 1505.1-2333.6 and 1526.0-1678.7 mg/kg, respectively. Alcaligenes faecalis, Pseudomonas azotoformans and Bacillus mycoides exhibited high tolerance to heavy metals salt and were selected for bioremediation. Post bioremediation analysis of the soil samples revealed a reduction in the concentration of heavy metals concentration with major reduction in the concentration of chromium in groups treated with P. azotoformans. Biostimulation of microorganisms with organic amendment effectively remediated heavy metals contaminated soil and can be employed in the treatment of such contaminated environments.