Optimization and scale-up of the production of rhamnolipid by Pseudomonas aeruginosa in solid-state fermentation using high-density polyurethane foam as an inert support.

To be competitive with common synthetic surfactants, the cost of production of rhamnolipid must be minimized by the fermentation process of non-foaming and low impurities. Herein, a novel solid-state fermentation process was developed for production of rhamnolipid by Pseudomonas aeruginosa SKY. The results were shown that high-density polyurethane foam is a satisfactory alternative to agro-industrial by-products for SSF of rhamnolipid. Palm oil and NaNO3 were promising carbon source and nitrogen source, respectively. Response surface methodology was employed to enhance the production of rhamnolipid. Palm oil, NaNO3 and liquid-to-solid ratios were significant factors. The optimal medium was developed as: 73.6 g/l palm oil; 3.0 g/l g NaNO3; 1.1 g NaCl; 1.1 g KCl; 3.4 g KH2PO4; 4.4 g K2HPO4; 0.5 g MgSO4·7H2O and 37.2 liquid-to-solid ratios. An overall 1.39-fold increase in rhamnolipid production was achieved in the optimized medium as compared with the unoptimized basal medium. Air pressure pulsation solid-state fermentation (APP-SSF) was applied to the experiment of scale-up for improving transfer efficiency of heat and mass. The yield of rhamnolipid reached 39.8 g/l in a 30 l APP-SSF fermenter. The crude extract of rhamnolipid lowered the surface tension of water to 28 mN/m and kept the critical micelle concentration at 50 mg/l. The work revealed the SSF with HPUF as an inert support was a promising fermentation system that could effectively produce rhamnolipid with low impurities, high productivity and low cost of production at a large scale.

Periploca forrestii Saponin Ameliorates Murine CFA-Induced Arthritis by Suppressing Cytokine Production.

Periploca forrestii Schltr. has been used as a Chinese folk medicine due to its versatile pharmacological effects such as promoting wounds and rheumatoid arthritis. However, the antiarthritic activity of Periploca forrestii saponin (PFS) and its active compound Periplocin has still not been demonstrated. Here, we evaluated the antiarthritic effects of PFS in adjuvant-induced arthritis (AIA) rats by intragastric administration at a dose of 50 mg/kg. The anti-inflammatory activities of Periplocin were also examined in LPS-induced AIA splenocytes and synoviocytes. PFS significantly ameliorated joint swelling; inhibited bone erosion in joints; lowered levels of IL-6 and TGF-ß1 in AIA rat splenocyte; and reduced joint protein expression levels of phospho-STAT3 and IKKα. Using LPS-induced AIA splenocytes, we demonstrate that Periplocin suppressed the key proinflammatory cytokines levels of IL-6, IFN-γ, TGF-ß1, and IL-13 and IL-22 and transcription factor levels of T-bet, GATA3, and C-Jun genes. Periplocin also suppressed LPS-induced cytokine secretion from synoviocytes. Our study highlights the antiarthritic activity of PFS and its derived Periplocin and the underlying mechanisms. These results provide a strong rationale for further testing and validation of the use of Periploca forrestii Schltr. as an alternative modality for the treatment of RA.