Journal of Bioscience and Biotechnology Discovery Volume 1. Page 83-88. Published 13th October, 2016 ISSN: 2536-7064: Article Number: JBBD-12.09.16-017 www.integrityresjournals.org/jbbd/index.html Full Length Research Preliminary study of mechanic workshop soil amended with juice extracted from Lime (Citrus aurantifolia) Stephen, E. 1* , Otorkpa, O. J. 2 , Adejo, P. O. 1 and Shaibu, L. 1 1 Department of Microbiology, Kogi State University, P.M.B. 1008, Anyigba-Kogi State, Nigeria. 2 Texila American University, Georgetown, Guyana, USA. *Corresponding Author. Email: Stephen.e@ksu.edu.ng. Tel: +234-8036347036. Copyright © 2016 Stephen et al. This article remains permanently open access under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Received 12th September, 2016; Accepted 5th October, 2016 ABSTRACT: Bioremediation potential of lime extract (Citrus aurantifolia) on mechanic workshop soil was studied for a period of 56 days. The microbial enumeration was carried out using serial dilution and pour plate method. The bacteria count ranged from 6.3×10 3 to 6.8×10 4 cfu/g for oil free soil (OFS), 0.8×10 3 to 9.8×10 4 cfu/g for mechanic workshop soil (MS) and 1.24×10 4 to 4.16×10 4 cfu/g for mechanic workshop soil amended with lime extract (MSAL). The fungal count ranged from 2.1×10 3 to 2.7×10 3 cfu/g for amended soil, 2.5×10 3 to 3.0× 10 4 cfu/g for unpolluted and 2.2×10 3 to 4.0×10 4 cfu/g for polluted soil. There were significant differences in both bacteria and fungi count at 5% probability level. Micrococcus sp, Staphylococcus sp, Pseudomonas sp, Bacillus sp, Proteus sp Mucor sp, Microsporum sp, Aspergillus niger, Aspergillus flavus, Saccharomyces sp, Rhizopus sp and Aspergillus fumigatus were isolated in this study. MSAL had higher moisture content, phosphorus, organic matter, organic carbon and nitrate compared to OFS and MS. There were significant differences (p<0.05) in the pH, phosphorus, organic matter, organic carbon between OFS, MS and MSAL. This study revealed that lime (Citrus aurantifolia) extract has a potential for remediating mechanic workshop soil. Keywords: Bioremediation, Citrus aurantifolia, lime extract, organic carbon. INTRODUCTION Contamination of soils with oil in the environment has been reported by Yakubu (2007) as a well recognised problem in today’s world. Oil spills affect many species of plants and animals in the environment as well as humans. Contamination of soils with petroleum hydrocarbons is a growing concern in many countries (Agamuthu et al., 2010). The indiscriminate disposal of spent lubricating oil by motor mechanics is a common source of spent lubricating oil contamination of soil in countries like Nigeria that do not enforce strict compliance to environmental laws (Ogbo et al., 2009). Spent engine oil is a common and toxic environmental contaminants not naturally found in the environment (Dominguez-Rosado and Pichtel, 2004). large amount of spent oil are liberated into the environment when motor oil is changed and disposed into the soil by motor mechanics and generator artisans including small scale lubricating oil merchants along the road (Odjegba and Sadiq, 2002; Achuba and Clarke- Peretiemo, 2008). Oil is released into the environment from exhaust system during engine use and also due to engine leaks (Osubor and Anoliefo, 2003). According to Ogbo et al. (2009), oil contamination causes low rate of germination in plants. Adam and Duncan (2002) also reported that this effect could be due to the oil which acts as a physical barrier preventing or reducing access of the seeds to water and oxygen. Oil released into the environment affects many plants, animals, microorganisms and humans within the oil impacted environment. Additionally, prolonged exposure to oil as well as high concentration of oil could cause the development of liver or kidney disease, possible damage to the bone marrow and an increased risk of cancer (Mishra et al., 2001). Petroleum products such as engine oil, petrol and diesel are used daily in various forms in mechanic workshops. These products tends to harden and change the colour of the soil, which may have untold hazards to automobile technicians (Udeani et al., 2009). Abandoned