Isolation and Identification of Biosurfactant Producing Bacterial Strain from Saline Soil Samples in Iran; Evaluation of Factors on Biosurfactant Production

Background: Biosurfactants are a group of valuable amphiphilic molecules that have been widely used in different industries such as pharmaceuticals and cosmetics. Objectives: The current study aimed to screen and identify a bacterial strain able to produce biosurfactant from environmental soil samples, followed by evaluating factors that contribute to biosurfactant production. Methods: The biosurfactants production was evaluated every 24 hours by emulsification index (EI), oil spreading ability, and surface tension measurement. Thereafter, the sequences of 16S rDNA genes and biochemical tests were performed to identify the isolated bacterial. Furthermore, the effect of different factors, including nitrogen, vegetable oil, and cations on biosurfactant productivity of the selected bacterial strain, was also evaluated. Results: In primary screening, out of the six bacterial strains, only one isolate was found to produce a hemolytic zone on the blood agar plate. The EI index was increased in a time-dependent manner with a maximum EI of 10% after 12h. Surface tension measurement revealed decreased surface tension (51 mN/m) after 12 hours' incubation compared to that of the blank sample. The selected isolate was recognized as Bacillus atrophaeus by 16S rDNA gene sequencing and biochemical test. All applied factors in culture media could decrease the surface tension of culture broth compared to that of the blank sample. Conclusions: This study demonstrated a Bacillus strain able to produce biosurfactants. Such biosurfactant producers would have great potentials in bioremediation activities and microbial enhanced oil recovery.

Application of Surface Tension Measurement to Determined Saturated Cooking Oil and Unsaturated Cooking Oil

Application surface tension measuring tool to distinguish saturated cooking oil and unsaturated cooking oil has been done. Th is study aims to apply the surface tension measuring tool as an alternative tool for distinguishing saturated cooking oil and unsaturated cooking oil. This study was conducted to distinguish the quality of cooking oil consumption in terms of the number of oil for frying. The method used in this research is the method Torsion Dynamometer conducted in three phases, the first preparation of tools and materials, the second data retrieval, and the third is data processing. The results showed that torsion Dynamometer can be used as a tool to distinguish saturated cooking oil and unsaturated cooking oil. Saturated cooking oil has a value of surface tension γ ± Δγ = (1.6604 ±0.01448) dyne/cm, while for unsaturated cooking oil has a value of surface tension γ ± Δγ = (1.3492 ± 0.03624) dyne/cm.