No abstract

In the present study, the special shake flasks, so-called ventilation flasks, are equipped with oxygen sensors and then an unsteady-state gas transfer model for shake flasks was developed and experimentally investigated for a wide range of gas transfer resistances (kplug). For the validation of our unsteady-state model to simulate the gas transfer in a biological system in the ventilation flasks, a strain of Corenobacterium glutamicum DM1730 was used as a model organism. For further easy processing, the resulting total mass-transfer resistance (kplug) is described as a function of the mass flow through the sterile plug (OTRplug) by an empirical equation. This equation is introduced into a simulation model that calculates the gas partial pressures in the headspace of the flask. Additionally, the gas transfer rates through the sterile closure and gas/liquid interface inside the flask are provided. This unsteady-state model would be a very useful method for scaling up from a shake flask to a fermentor; comparing the results of the gas concentration in the gas phase, there is good agreement between the introduced unsteady-state model and experimental results for the biological system.

No abstract

-A rhamnolipid producing bacterium, Pseudomonas aeruginosa HR was isolated from south of Iranian oil wells. In the previous study, effects of main factors of cultivation on production of biosurfactant by this strain were evaluated and their optimized values were determined. In the present paper, the ability of produced biosurfactant in oil recovery was investigated. For this purpose, its affect on enhanced oil recovery in sand pack and core holder obtained from oil wells was evaluated. It was found that the maximum oil recovery in saturated sand pack column and in saturated core holder of crude oil were 23.6 and 64%, respectively. Then, in core test mathematical model was proposed by considering interactions between given parameters. Furthermore, dependence of residual oil recovery on the process of core washing during injection of biosurfactant was investigated. Finally, capillary desaturation curve was compared with core flood data.