title: Strategies for improved rhamnolipid production by Pseudomonas aeruginosa PA1.
abstract: Rhamnolipids are biosurfactants with potential for diversified industrial and environmental uses. The present study evaluated three strategies for increasing the production of rhamnolipid-type biosurfactants produced by Pseudomonas aeruginosa strain PA1. The influence of pH, the addition of P. aeruginosa spent culture medium and the use of a fed-batch process were examined. The culture medium adjusted to pH 7.0 was the most productive. Furthermore, the pH of the culture medium had a measurable effect on the ratio of synthesized mono- and dirhamnolipids. At pH values below 7.3, the proportion of monorhamnolipids decreased from 45 to 24%. The recycling of 20% of the spent culture medium in where P. aeruginosa was grown up to the later stationary phase was responsible for a 100% increase in rhamnolipid volumetric productivity in the new culture medium. Finally, the use of fed-batch operation under conditions of limited nitrogen resulted in a 3.8-fold increase in the amount of rhamnolipids produced (2.9 g L(-1)-10.9 g L(-1)). These results offer promising pathways for the optimization of processes for the production of rhamnolipids.
authors.affiliation: Department of Basic Science/Faculty of Biological Science and Health, Universidade Federal dos Vales do Jequitinhonha e Mucuri , Diamantina, Minas Gerais , Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Soares Dos Santos
authors.affiliation: Department of Biochemical Engineering/School of Chemistry, Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil.
authors.forename: Nei
authors.initials: N
authors.lastname: Pereira
authors.affiliation: Department of Biochemistry/Institute of Chemistry, Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil.
authors.forename: Denise M G
authors.initials: DM
authors.lastname: Freire
keywords: Biosurfactant; Homoserine lactones; Pseudomonas aeruginosa; Rhamnolipid