1 Screening and Characterization of biosurfactant producing 1 bacteria isolated from Arabian Sea coast of Karachi 2 Erum SHOEB*, Nuzhat AHMED, Jameela AKHTER, Uzma BADAR, Khaizran SIDDIQUI, Faiza A. 3 ANSARI, Maheen WAQAR, Samina IMTIAZ, Nimrah AKHTAR, Qurat ul Ain SHAIKH, Roaunq BAIG, 4 Saba BUTT, Saema KHAN, Sidra KHAN, Shahid HUSSAIN, Bashir AHMED, Maqsood A. ANSARI 5 Department of Genetics, University of Karachi, Karachi-75270, Pakistan 6 *Corresponding Author: Dr. Erum Shoeb, Assistant Professor, Department of Genetics, 7 University of Karachi, Karachi-75270, Pakistan. erumsh@uok.edu.pk 8 1. ABSTRACT 9 The aim of the present study was to investigate biosurfactant producing culturable bacteria 10 inhabit the Karachi coast of Arabian Sea. Overall, 15 seawater samples collected from 11 Arabian Sea coast of Karachi. Isolation, characterization and screening for 89 biosurfactant 12 producing bacterial strains conducted through eight conventional screening tests. Through 13 GSP agar plate method 22 strains were found to be Pseudomonas aeruginosa and Gram 14 reaction revealed 70% of the isolates to be Gram negative. 24% of the isolates showed 15 hemolytic activity; 44% exhibited positive results for oil spreading test; 54% showed 16 emulsification to at least one of the three hydrocarbons tested; BATH assay results 17 indicated maximum adhesion for hexane; 52.8% produced positive results for CTAB agar 18 plate assay; Drop-collapse activity was found in 84% of the isolates; Emulsification assay 19