Isolation and identification of biosurfactant-producing bacteria from hydrocarbon-contaminated mechanic workshop soils in Port Harcourt, Nigeria

Nengi-Benwari A. O., Owhonka Aleruchi, Ibiene Rogers Longjohn and Chidinma Favour Opara

Microbiology Research International
Published: February 24 2025
Volume 13, Issue 1
Pages 23-29

Abstract

Biosurfactants are microbial-derived compounds known for their ability to reduce the surface tension of viscous liquids. They play a key role in solubilizing hydrophobic substrates, such as petroleum. Soils in mechanic workshops are often contaminated with petroleum or crude oil, making them ideal environments for biosurfactant-producing bacteria. This study aimed to isolate and characterize such bacteria from mechanic workshops in Port Harcourt, Nigeria, for potential bioremediation applications. Soil samples were collected from five different mechanic workshop sites in Port Harcourt. Bacterial enumeration revealed counts ranging from 7.85×10⁴ to 2.01×10⁵ CFU/g, with Sample D having the highest bacterial count and Sample A the lowest. Microbiological tests identified the bacterial isolates as belonging to the genera Bacillus (15%), Sphingomonas (10%), Klebsiella (20%), Staphylococcus (20%), Proteus (5%), Escherichia coli (25%), and Paenibacillus (5%). Biosurfactant production was assessed using three screening methods: the oil spreading assay, the drop collapse assay, and foaming capacity. Bacillus spp. and Klebsiella spp. tested positive for all three assays, indicating their strong biosurfactant-producing potential. Escherichia coli was positive for the drop collapse assay but negative for oil spreading and foaming capacity. Sphingomonas spp. tested positive for the drop collapse assay and foaming capacity but negative for the oil spreading assay. Paenibacillus polymyxa was positive for the oil spreading assay and foaming capacity but negative for the drop collapse assay. Staphylococcus spp. was positive only for foaming capacity, while Proteus spp. was positive for the oil spreading assay and drop collapse assay but negative for foaming capacity. The study concluded that Bacillus spp. and Klebsiella spp. exhibited the highest biosurfactant-producing activity. These findings highlight the potential of mechanic workshop soils in Port Harcourt as a valuable source of biosurfactant-producing bacteria, which could be utilized for bioremediation purposes.

Keywords: Biosurfactants, bioremediation, mechanic workshop soils, petroleum contamination, bacterial isolation, screening assays.

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