Isolation of biosurfactant producers from hydrocarbon contaminated water sample

Biosurfactants are heterogeneous surface active compounds released by microorganisms, which adhere to cell surface or are excreted extracellularly in the growth medium. These can be divided into low molecular weight molecules, that lower surface and interfacial tensions efficiently and high-molecular-weight polymers that bind tightly to surfaces. In the past two decades, biosurfactants have gained increasing attention due to their useful properties such as biodegradability, low toxicity, ecological acceptability and ability to be produced from renewable and cheaper substrates. The objective of this study was to isolate and identify the biosurfactant producing bacteria from the water sample. Mixed raw effluent (MRE) and drainage water samples were serially diluted and spread plated on the Minimal salt medium (MSM) agar supplemented with 1 % (vlv) crude palm oil as carbon source. To confirm the ability of isolates in biosurfactant production, various biosurfactant activity, assay and test were conducted. A total of 12 isolates, 2 isolates from MRE sample and 10 isolates from drainage water sample were screened for the presence of surface-active agent producing bacteria using the red blood cell haemolysis test, drop collapse test and emulsification assay. There are 1 isolate from MRE sample and 6 isolates from drainage water sample resulted beta-haemolysis as it is complete haemolytic activity. . In drop collapse test, only 1 isolate from MRE sample and 3 isolates from drainage water sample exhibited negative score. The highest emulsification activity resulted by isolate Ea2b from drainage water sample, 62.5% and the lowest is Ec5c and Fa1c showed only 6.3%. A total of 12 isolates were successfully characterized by cell and colony morphology. The size of purified DNA fragment is 1324bp after amplified it by using primer of 16S 68F and 16S 1392R.