Contents lists available at ScienceDirect International Biodeterioration & Biodegradation journal homepage: www.elsevier.com/locate/ibiod Application of biosurfactant for enhancement of bioremediation process of crude oil contaminated soil Rupshikha Patowary a , Kaustuvmani Patowary a , Mohan Chandra Kalita b , Suresh Deka a,* a Environmental Biotechnology Laboratory, Life Sciences Division, Institute of Advanced Study in Science & Technology (IASST), Paschim Boragaon, Guwahati 781 035, Assam, India b Department of Biotechnology, Gauhati University, Guwahati 781014, India ARTICLE INFO Keywords: Biosurfactant Pseudomonas aeruginosa SR17 Bioremediation Oil contamination PAHs ABSTRACT In the present study, a biosurfactant produced by Pseudomonas aeruginosa SR17 was utilized to evaluate its efficiency in enhancement of bioremediation of oil contaminated soil. The degradation of total petroleum hy- drocarbon (TPH) on application of rhamnolipid biosurfactant at 1.5 g L -1 was found to be 86.1% and 80.5% in two soil samples containing 6800 ppm and 8500 ppm TPH respectively. The efficiency of biosurfactant was also compared with a frequently used synthetic surfactant, sodium dodecyl sulphate (SDS) that resulted in 70.8% and 68.1% degradation of TPH from the same contaminated soil samples. GC-MS based analysis showed the presence of poly aromatic hydrocarbons (PAHs) namely indene, chamazulene, naphthalene, phenanthrene, anthracene, fluorene, floranthene, benz(b)fluorene and benz(d)anthracene in the soil samples. Rhamnolipid treatment eliminated 3 PAHs namely floranthene, benz(b)fluorene, and benz(d)anthracene completely within six months and the remaining PAHs were depleted up to 60–80%, within the same period. The efficient degradation of PAHs and other components of TPH on application of the biosurfactant were attributed to enhanced heterotrophic bacterial population. It was also found that the degradation of oil contaminants led to alteration of certain vital physico-chemical properties of the soil. 1. Introduction Petroleum oil is the main source of energy for most of the in- dustrialized nations of the world. Various oil exploration activities, transportation, and accidental seepage or leakage of oil during different processes of oil recovery, leads to the release of tremendous amount of hydrocarbon wastes into the environment which causes major pollution (Peng et al., 2008). Hydrocarbon contaminants are highly hydrophobic, recalcitrant and persistent in nature as they are very difficult to re- mediate from the environment. In soil, contamination of hydrocarbon often leads to possibilities of uptake of the contaminants by the plants that are grown in the contaminated sites (Fismes et al., 2002). More- over, from those plants, the hydrocarbon contaminants can further be introduced to animal and human populations through food chain (Alagic et al., 2015). Polyaromatic hydrocarbons (PAHs) are the com- ponents of crude oil that are given prime attention due to their possible mutagenic and carcinogenic property (Ghosh et al., 2014). PAHs have been placed in the 9th position on the ATSDR (Agency for Toxic Sub- stances and Disease Registry) list and studies also reported that ex- posure to PAHs can lead to various forms of cancer (Lee and Shim, 2007; Yoon et al., 2007). Thus considering the harmful effects of the hydrocarbon oil contaminants, it is utmost necessary to take measures for mitigating their level in the environment. Various techniques such as land filling, incineration, and chemical treatments are widely used for cleaning up oil polluted sites, but those techniques are highly ex- pensive and can also pose additional risks to the environment due to their toxic and non-biodegradable nature. One of the promising methods to rehabilitate the oil polluted sites is the use of bioremedia- tion technology, which is an eco-friendly, cost-effective and sustainable approach (Guntupalli et al., 2016). Many researchers have conducted studies involving microorganisms to remediate oil contaminated en- vironment (Roy et al., 2014; Zhang et al., 2014). A large number of indigenous microorganisms inhabiting in the oil polluted sites, posses the ability to degrade hydrocarbon contaminants, although the de- gradation process of such compounds is hindered by their high re- calcitrant and low bioavailability nature (Calvo et al., 2008). A suitable method that can be adopted to fasten the biodegradation process of such organic compounds is the involvement of biosurfactant in the biodegradation process. Various strains of microorganisms such as Serretia mercencis, https://doi.org/10.1016/j.ibiod.2018.01.004 Received 7 November 2017; Received in revised form 28 December 2017; Accepted 8 January 2018 * Corresponding author. E-mail address: sureshdeka@iasst.gov.in (S. Deka). International Biodeterioration & Biodegradation xxx (xxxx) xxx–xxx 0964-8305/ © 2018 Elsevier Ltd. All rights reserved. Please cite this article as: Patowary, R., International Biodeterioration & Biodegradation (2018), https://doi.org/10.1016/j.ibiod.2018.01.004