ماندانا زارعی

Biosurfactant are amphiphilic compounds and surface-active substances derived from living organism, especially microorganism. Biosurfactant are being investigated as replacements for synthetic surfactants because they are biodegradable, less sensitive to extreme environments and can be produced on renewable substrates. The potential applications of biosurfactant in industrial include emulsification and foaming for food processing, wetting and phase dispersion for cosmetic and textiles, bioremediation and enhancement of oil recovery (EOR). It is the first time those associated microorganisms are isolated from sponges and also a marine natural product extracted from them in Iran. 2 species of marine sponges was collected from Coast of Kharko Island in Persian Gulf by SCUBA diving at 10-15depht. The samples were kept in 1 litter of Sterilized Aged Seawater (SAS) for 2h. The specimens were kept in oven at 40 0C for 2h and were stored at -20 0C. 2 cm3 of sponge tissue was excised from the internal mesohyl area and then the tissue was homogenized with phosphate buffered saline by tissue homogenizer. The resultant was placed on various isolation media. The inoculated plates were incubated at 27 0C for 14 days in dark. For growth curve of biosurfactant producer, the culture was inoculated in 500 ml Erlenmeyer flaks each containing 100 ml production media. The experiment was designed for 2 weeks. Cell growth was determined by monitoring the optical density of culture broth at 620 nm. The biomass was determined from the cells after centrifugation of the culture broth at 10000 rpm in 4 0c for 10 min. the dry cell weight was obtained from the cell plates by washing twice with distilled water and drying in hot air oven at 105 0c for 24 hours. The emulsification index (E24) was measured by adding crude oil to equal volume of extracted biosurfactant and homogenized in a vortex at high speed for 2 min. Based on the present findings, sponge associated marine microorganisms are the g