American Journal of Life Sciences 2014; 2(6-3): 22-30 Published online January 26, 2015 (http://www.sciencepublishinggroup.com/j/ajls) doi: 10.11648/j.ajls.s.2014020603.15 ISSN: 2328-5702 (Print); ISSN: 2328-5737 (Online) Isolation, Cloning and Expression of Rhamnolipid Operon from Pseudomonas aeroginosa ATCC 9027 in Logarithmic Phase in E. coli BL21 Amin Jafari 1 , Jamshid Raheb 1, * , Hassan Bardania 1 , Behnam Rasekh 2 1 National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran 2 Department of Petroleum Biotechnology, Biotechnology Research Center, Research Institute of Petroleum Industry, Tehran, Iran Email address: jam@nigeb.ac.ir (J. Raheb) * Corresponding author To cite this article: Amin Jafari, Jamshid Raheb, Hassan Bardania, Behnam Rasekh. Isolation, Cloning and Expression of Rhamnolipid Operon from Pseudomonas aeroginosa ATCC 9027 in Logarithmic Phase in E. coli BL21. American Journal of Life Sciences. Special Issue: Microbiology Research. Vol. 2, No. 6-3, 2014, pp. 22-30. doi: 10.11648/j.ajls.s.2014020603.15 Abstract: The rhamnolipid operon from Pesudomonas strain with the native promoter was not expressed in logarithmic phase of Ecoli. The expression of rhamnolipid in logarithmic phase of growth whether the regulatory elements of the operon are eliminated or not was investigated. The rhamnolipid operon was identified in Pseudomonas aeruginosa ATCC 9027 and the rhlAB genes related to rhamnolipid were isolated and amplified by PCR. The PCR product was cloned in pET 23a expression vector and transferred into the E. coli BL21. The expression of rhlAB genes was analyzed and our results showed that the synthesis of monorhamnolipid occurred in logarithmic phase. In addition this data demonstrated a higher production of rhamnolipid in recombinant Ecoli Bl21compared to that indigenous Pseudomonas aeruginosa ATCC 9027. Keywords: MEOR, Manipulated E. coli BL21, Monorhamnolipid, Logarithmic Phase 1. Introduction Biosurfactants are known for their surface tension reduction activity with two different characteristics: hydrophobic and hydrophilic and therefore possess the ability to penetrate into two different phases to reduce the surface tension [15]. Some bacteria and fungi produce and utilize a group of biological surfactants which are called biosurfactant. Pseudomonas aeroginosa produce a kind of glycolipid biosurfactant, known as rhamnolipid. The bacteria apply surfactants to utilize the unusual carbon sources such as crude oil and hexadecane. Rhamnolipid molecule containing two moieties of rhamnose sugar and fatty group[1], a dimmer of two fatty acids that are usually medium long chain. P. aeroginosa produce two types of rhamnolipid which differ in the number of rhamnose sugar. The rhamnolipid molecule that has one or two molecule of rhamnose is called monorhamnolipid and dirhamnolipid respectively. This biomolecule is produced by some microorganisms such as Burkholderia and P. aeroginosa [2] and has a wide range of applications for the bacterial cells. Rhamnolipid biosurfactant can be applied as the wetting agent for friction reducing of bacterium and medium, that leads to easier surface movement for bacterial cells [7, 33]. Furthermore, rhamnolipid-producing bacteria can utilize this biosurfactant for competition in microbial population [1, 13] swarming, altering the cell surface hydrophobicity [4, 3], feeding [16] and etc. This green and biodegradable biosurfactant can functionally acts as synthetic surfactant that has not harmful effects on environment and health. This molecule can also be used in pharmaceutical industry, oil industry, food industry and etc [5]. The application of rhamnolipid in oil industry is due to its capability to remove the oil spills leaked from tankers, and this molecule can also remove heavy metals from the soils [8, 22]. Another application of this biosurfactant in oil industries is based on its ability to reduction of surface tension. In oil reservoirs, there is much crude oil which is viscose and hardly moveable. Running of heavy crude oil to the main reservoir is time consuming and, pumping of such viscose fossil