Pseudomonas aeruginosa PAO1 as a model for rhamnolipid production in bioreactor systems

Abstract

Rhamnolipids are biosurfactants with interesting physico-chemical properties. However, the main obstacles towards an economic production are low productivity, high raw-material costs, relatively expensive downstream processing, and a lack of understanding the rhamnolipid production regulation in bioreactor systems. This study shows that the sequenced Pseudomonas aeruginosa strain PAO1 is able to produce high quantities of rhamnolipid during 30 L batch bioreactor cultivations with sunflower oil as sole carbon source and nitrogen limiting conditions. Thus PAO1 could be an appropriate model for rhamnolipid production in pilot plant bioreactor systems. In contrast to well-established production strains, PAO1 allows knowledge-based systems biotechnological process development combined with the frequently used heuristic bioengineering approach. The maximum rhamnolipid concentration obtained was 39 g/L after 90 h of cultivation. The volumetric productivity of 0.43 g/Lh was comparable with previous described production strains. The specific rhamnolipid productivity showed a maximum between 40 and 70 h of process time of 0.088 g(RL)/g(BDM)h. At the same time interval, a shift of the molar di- to mono-rhamnolipid ratio from 1:1 to about 2:1 was observed. PAO1 not only seems to be an appropriate model, but surprisingly has the potential as a strain of choice for actual biotechnological rhamnolipid production.

Evaluation of Biosurfactants and Surfactants for Crude Oil Contaminated Sand Washing

“…With this method, the production of rhamnolipids (Rha-C10-C10 and Rha2-C10-C10) by P. aeruginosa PTCC 1310 could be proven. These results are in agreement with other research works Müller et al, 2010).…”

Fatty acid synthesis pathway provides lipid precursors for rhamnolipid biosynthesis in Burkholderia thailandensis E264

“…1). We chose P. aeruginosa PAO1 for this comparative study, as it has been shown to be a model for the study of rhamnolipid production (Müller et al 2010). …”

Structural and physiochemical characterization of rhamnolipids produced by Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa in single strain and mixed cultures

“…Although the growth rate was not substantially influenced by the experiment setup, the rhamnolipids concentrations obtained in the bioreactor were higher. Müller et al (2010) reported a significant increase of rhamnolipids production by P. aeruginosa PAO1 when cultivation was transferred from shaken flasks to a large scale bioreactor. The same phenomenon was observed in this work; the transition from small scale cultivations (Erlenmeyer flasks) to a 1.7 l working volume bioreactor led to up to five times higher production in the bioreactor -in single strain cultures the rhamnolipids production was the highest in P. aeruginosa cultivation (4.8 g/l) and second highest (3.8 g/l) in E. asburiae cultivation.…”