Characterization of Di-Rhamnolipid Biosurfactant in Recombinant Escherichia coli

Surfactants are amphiphilic molecules, which have hydrophilic and hydrophobic groups. Surfactants have an important role in various fields including agriculture, cosmetics, pharmaceuticals, bioremediation, and the petroleum industry especially EOR but because synthetic surfactants are not biodegradable, it is necessary to produce biodegradable surfactants such as rhamnolipid biosurfactants. Rhamnolipid is a glycolipid biosurfactant produced by Pseudomonas aeuruginosa. This species is a pathogen, so it is needed to overcome this problem by cloning the rhamnolipid gene into Escherichia coli for large-scale production. Rhamnolipid biosynthesis includes three main genes, rhlA, rhlB, and rhlC. The rhlAB produces mono-rhamnolipid and rhlABC produces di-rhamnolipid. The construction involved one plasmid pPM RHLABC (di-rhamnolipid) with T7lac promoter. Characterization of surfactants by E24, IFT, and CMC analysis showed that di-rhamnolipid biosurfactant has the best activity (70%, 0.8 mN/m, and 300 mg/L) than chemical surfactant, sodium dodecyl sulfate (46%, 4.7 mN/m, and 2000 mg/L) at pH 7, 25 °C, and 0% salinity. The conclusion from this research shows that the characteristics of di-rhamnolipid are very promising in the utilization of industrial-scale including EOR technology, agriculture, and pharmacy

Ipr1 Regulation by Cyclic GMP-AMP Synthase/Interferon Regulatory Factor 3 and Modulation of Irgm1 Expression via p53

ABSTRACT Intracellular pathogen resistance 1 (Ipr1) has been found to be a mediator to integrate cyclic GMP-AMP synthase (cGAS)–interferon regulatory factor 3 (IRF3), activated by intracellular pathogens, with the p53 pathway. Previous studies have shown the process of Ipr1 induction by various immune reactions, including intracellular bacterial and viral infections. The present study demonstrated that Ipr1 is regulated by the cGAS-IRF3 pathway during pathogenic infection. IRF3 was found to regulate Ipr1 expression by directly binding the interferon-stimulated response element motif of the Ipr1 promoter. Knockdown of Ipr1 decreased the expression of immunity-related GTPase family M member 1 (Irgm1), which plays critical roles in autophagy initiation. Irgm1 promoter characterization revealed a p53 motif in front of the transcription start site. P53 was found to participate in regulation of Irgm1 expression and IPR1-related effects on P53 stability by affecting interactions between ribosomal protein L11 (RPL11) and transformed mouse 3T3 cell double minute 2 (MDM2). Our results indicate that Ipr1 integrates cGAS-IRF3 with p53-modulated Irgm1 expression.