Abstract

Background/Aim: Anthropogenic contamination alters soil and dust microbial characteristics and long-term exposure to such environmental media can cause chronic human health disorders. This research was aimed at assessing the occurrence, abundance and distribution of pathogenic microorganisms in soils and dust of an urban area, Warri. Methods: Ten sampling sites were selected using stratified-random sampling method and a total of forty soil and twenty dust samples were collected. Soil samples were collected from four depths (25, 50, 75 and 100 cm) and dust samples were collected in duplicates per site. Total bacterial and fungal counts were estimated using pour plate technique and microbial isolates were identified by their cultural, morphological and biochemical characteristics. Results: The microbial load in the dust samples ranged from 1.0×106 - 6.9×106 CFU/g for bacteria and 1.1×106 - 6.0×106 CFU/g for fungi. In soil, it ranged from 1.0×106 - 6.9×106 CFU/g for bacteria and 2.0×106 - 9.0×106 CFU/g for fungi. Total bacterial counts were at highest levels in agricultural areas while the highest fungal counts were recorded in market areas. Top soil samples revealed relatively higher microbial counts compared to those from the second depth, with a further increase noted at the third and fourth depths. Statistical analysis using t-test revealed a significant difference (P<0.05) in the total bacterial count from soil and dust samples. Predominant bacteria such as Staphylococcus sp., Sphingomonas sp., Pseudomonas sp., Bacillus subtilis and Escherichia coli, and fungi, such as Penicillium sp and Aspergillus sp. were identified.Conclusion: Varied isolated species of bacteria and fungi were peculiar to different anthropogenic environments and soil depths. The average microbial count indicates that bacterial abundance was lower in dust than soil and surface soil is rich in bacterial population. Extensive monitoring of soil and dust microbial quality is needed to maintain optimal health conditions for urban dwellers.

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