Optimization of Emulsifier Production by Marine Bacteria Isolated from the Makran Sea

The Makran Sea is a complex marine environment. The purpose of this research is screening of emulsifier-producing bacteria in this marine environment and optimization of emulsifier production by the best-producing strain. Marine samples (seawater and sediments) were collected from four different zones in the Makran Sea. The emulsification activity index (E₂₄) and Bacterial Adhesion To Hydrocarbons (BATH) were used to select the best emulsifier-producing strains. The prevalent strains were identified by PCR. The optimization of the emulsifier production medium by the best strain was done by two-level factorial design. Seventeen emulsifier-producing strains were isolated from sediments and seawater in the Makran Sea. The strains M6, BS-2, and J6 were selected between all isolates because they have 83%, 91%, and 85% emulsification activity (E₂₄) respectively. The results of sequencing confirmed that these three strains (M6, BS-2, and J6) belong to Cobetia marina, Shewanella alga, and Thalassospira permensis respectively. Maximum emulsifier production occurred at crude oil concentration (4%, v/v), peptone (2.5 g/L), yeast extract (1.5 g/L), molasses (2%), and at a temperature of 25 °C. The results of this research confirmed that the Makran Sea has the potential to reach robust marine bacteria with different biotechnological applications.