Evaluation of Different Screening Methods for Biosurfactant Producers Isolated from Contaminated Egyptian Samples Grown on Industrial Olive Oil Processing Waste

Abstract

The present study aimed to screen biosurfactant producing microorganisms isolated from different Egyptian samples viz. soil sample contaminated with oil from fuel station, soil sample contaminated with kerosene from classic bread oven, samples from wall of drainage tube of kitchen and bathroom, also waste sample from gas cooktops of kitchen stove. All isolation samples were streaked on MSM medium supplemented with 1% olive oil processing waste as a sole carbon source to recover bacterial isolates with biosurfactant activity. Different screening methods e.g. Oil spreading assay, Emulsification index E24, Drop collapse test, Blue agar plate method (Cetyl trimethyl ammonium bromide-CTAB), Blood agar haemolysis, Reduction in SFT and Phenol sulfuric acid method were used to screen microbial biosurfactant producers. Fifty five bacterial isolates were obtained, consecutive screening was carried out between isolates to select the most promising biosurfactant producer. The selected isolate produced potential biosurfactant that belongs to glycolipid and identified by Biochemical and 16S rRNA analysis and was found belongs to Pseudomonas aeruginosa PAO1. Conclusion: A combination of different methods is required for a successful screening, but it is recommend using both of drop collapse and CTAB tests, suggesting that strains highly active in one method were active in the other method. In addition, surface tension measurement and phenol sulfuric acid reaction is a must in case of the biosurfactant is of glycolipid type (rhamnolipid) to confirm the presence of anionic biosurfactant. In the present investigation using of efficient biosurfactant producer (P. aeruginosa PAO1) which prefer limited oxygen requirements (microaerobic) growing on low cost substrate (olive oil processing waste) is a privilege in the production cost.