بررسي شرايط توليد رامنوليپيد حاصل از سويه هاي مختلف سودوموناس آئروژينوزا

Optimization of the production of rhamnolipids by Pseudomonas aeruginosa strains

Background and objectives: Biosurfactants are a heterogenous group of surface active molecules produced on microbial cell surfaces or excreted extracellulary. They are powerful natural emulsifiers, solubilizing and wetting agents. Rhamnolipids belong to the glycolipid class of biosurfactants and were first isolated from Pseudomonas aeruginosa. Rhamnolipids are an attractive alternative to synthetic surfactants because of low toxicity, better environmental compatibility, and high selectivity. The aim of this work was to optimize biosurfactants production by Pseudomonas aeruginosa ATCC 9027 and two hyper producing mutant strains (M6 and M34) using different culture conditions. Materials and methods: The rhamnolipid-producing medium (Lindhardt) containing different carbon sources were inoculated with 5% (v/v) of a 24-h preculture. The cultures were then incubated on a rotary shaker at different temperatures and rates, with different durations. The rhamnolipids were precipitated by acidification of the culture below pH 2.0 and the precipitate was extracted by organic solvents. Results: The results showed that the carbon source used in a culture medium, bacterial strain, and temperature are the most important factors in the production of biosurfactants. The maximum rhamnolipid concentration, 2.21g/l, was reached when the M34 strain was incubated at 30oC and 150 rpm for 7 days using Canola oil as the carbon source Conclusion: The mutant strain M34 can be used to produce large amounts of rhamnolipid for food, chemical, pharmaceutical and hygienic applications.