Optimization of Lipopeptide Biosurfactant Production by Salibacterium sp. 4CTb in Batch Stirred-Tank Bioreactors

Halophilic microorganisms are potentially capable as platforms to produce low-cost biosurfactants. However, the robustness of bioprocesses is still a challenge and, therefore, it is essential to understand the effects of microbiological culture conditions through bioreactor engineering. Based on a design of experiments (DOE) and a response surface methodology (RSM) tailored and taken from the literature, the present work focuses on the evaluation of a composite central design (CCD) under batch cultures in stirred-tank bioreactors with the halophilic bacteria Salibacterium sp. 4CTb in order to determine the operative conditions that favor mass transfer and optimize the production of a lipopeptide. The results obtained showed profiles highlighting the most favorable culture conditions, which lead to an emulsification index (E-24%) higher than 70%. Moreover, through the behavior of dissolved oxygen (DO), it was possible to experimentally evaluate the higher volumetric coefficient of mass transfer in the presence of lipopeptide (k(L)a = 31 1/h) as a key criterion for the synthesis of the biosurfactant on further cell expansion.

Automated summary

This study aimed to evaluate the operational conditions for producing lipopeptides by halophilic bacteria in stirred-tank bioreactors under batch cultures. The results showed that under the most favorable culture conditions, the emulsification index was higher than 70%, which is crucial for the synthesis of biosurfactants.