Heavily polluted mechanic workshop soil and its phenanthrene-degrading Bacillus thuringiensis

• Published in: The Microbe Vol. 4; p. 100104
• Main Authors: Obayori, Oluwafemi Sunday, Ashade, Ahmeed Olalekan, Salam, Lateef Babatunde, Adeyemo, Adedamola Caleb, Oladejo, Sarah Olanrewaju, Abanikannda, Opeyemi Nasrah, Oyebade, Adedayo Elena
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2024; Elsevier
• Subjects: Anthracene; Bacillus thuringiensis; Biodegradation; Phenanthrene; Polluted Soil; Biodegradation; Polluted Soil; Anthracene; Phenanthrene; Bacillus thuringiensis
• ISSN: 2950-1946; 2950-1946
• DOI: 10.1016/j.microb.2024.100104

Mechanic workshops in residential areas are sites referenced for small-scale chronic contamination with petroleum hydrocarbons (HC) and associated pollutants like heavy metals. The main aim of this study was to isolate from a mechanic workshop soil in Lagos a novel indigenous bacterium with potential for degradation of phenanthrene, a model polyaromatic compound. Gas chromatographic analysis revealed concentrations of HC (20,055 mg kg-1), lead (156.19 mg kg-1) and zinc (202.005 mg kg-1) in excess of regulatory limits in the soil. Continuous enrichment resulted in the isolation of a bacterium strain ALSL2, which was identified by 16S rRNA gene sequencing as Bacillus thuringiensis. Strain ALSL2 showed broad specificity for a range of HCs including phenanthrene, anthracene, biphenyl, dibenzothiophene, crude oil, diesel and kerosene and also showed biosurfactant production with emulsification index 55.2 %, 65.7 % and 58.7 % on crude oil, kerosene and vegetable oil respectively. The isolate showed evidence of dioxygenase activity and utilized metabolites of aromatic hydrocarbon degradation including 1-naphthol and O-phthalate. At the end of 10 days 51.45 % of phenanthrene was degraded at the rate of 7.922 mg l−1 d−1, degradation constant 0.073 d−1, and half-life 9.864 d. The corresponding values for anthracene were 69.11 %, 9.92 mg l−1 d−1., 0.11 d−1, and 5.924 d respectively. Our findings represent a remarkable addition to available indigenous bioresources with potential for application in bioremediation, and further highlight mechanic workshop soils as veritable source of such isolate. [Display omitted] •GC-FID of soil revealed concentrations of total hydrocarbons, lead and zinc in excess of regulatory limits.•Isolate was identified by 16S rRNA gene sequencing as Bacillus thuringiensis.•Strain ALSL2 used phenanthrene, anthracene, biphenyl, dibenzothiophene, crude oil, diesel and kerosene.•ALSL2 tested positive to beta haemolysis and biosurfactant production.•Isolate showed dioxygenase activity and utilized 1-naphthol and O-phthalate.