Author(s)

A. S. Al-Dousari, K. Majki, S. Moustafa & E. Al-Saleh

Abstract

The increase in human population is usually associated with increased waste production and by-products of urbanization. One such product of urbanization is heavy metals such as lead that at high concentrations have detrimental effects on human health as established previously. However, little is known about the effects of lead on the growth, activity and community of soil microbiota. For this purpose, the effects of lead on the microbiota of roadside soil samples collected from different distances from main roads in Kuwait were investigated. The addition of lead to soils decreased significantly (P<0.05) the counts and respiration of the total heterotrophic bacteria in particular in soils harbored lower concentrations of lead. Furthermore, the identification of soil bacteria showed the dominance of Gram-negative bacteria with high potentials to tolerate multiplicity of heavy metals where the order of increasing toxicity of heavy metals on tested bacteria was lead < chromium < aluminium < cobalt < nickel < mercury < cadmium. Moreover, based on 16S-RFLP analyses, it was demonstrated that soils containing higher concentrations of lead harboured less diverse bacterial communities. Results suggested that changes in soil microbiota are attributed to atmospheric lead apparently originated from car emissions. Keywords: metal-resistant Gram-negative bacteria, lead-resistant bacteria, roadside soil contamination, soil microbiota. 1 Introduction Roadside soil is a major sink of heavy metals (e.g. lead, zinc, cadmium, chromium, nickel, and copper) and hydrocarbons pollutants (e.g. gasoline, gas oil, and kerosene) in the environment [1] such as roadside soils [2]. Lead is used

Keywords

metal-resistant Gram-negative bacteria, lead-resistant bacteria, roadside soil contamination, soil microbiota.