title: Oxygen-controlled biosurfactant production in a bench scale bioreactor.
abstract: Rhamnolipids have been pointed out as promising biosurfactants. The most studied microorganisms for the aerobic production of these molecules are the bacteria of the genus Pseudomonas. The aim of this work was to produce a rhamnolipid-type biosurfactant in a bench-scale bioreactor by one strain of Pseudomonas aeruginosa isolated from oil environments. To study the microorganism growth and production dependency on oxygen, a nondispersive oxygenation device was developed, and a programmable logic controller (PLC) was used to set the dissolved oxygen (DO) concentration. Using the data stored in a computer and the predetermined characteristics of the oxygenation device, it was possible to evaluate the oxygen uptake rate (OUR) and the specific OUR (SOUR) of this microorganism. These rates, obtained for some different DO concentrations, were then compared to the bacterial growth, to the carbon source consumption, and to the rhamnolipid and other virulence factors production. The SOUR presented an initial value of about 60.0 mgO(2)/g(DW) h. Then, when the exponential growth phase begins, there is a rise in this rate. After that, the SOUR reduces to about 20.0 mgO(2)/g(DW) h. The carbon source consumption is linear during the whole process.
authors.affiliation: Programa de Engenharia Química, Instituto Alberto Luiz Coimbra de Pós Graduação e Pesquisa de Engenharia, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, Rio de Janeiro, Brazil. frederico@peq.coppe.ufrj.br
authors.forename: Frederico de Araujo
authors.initials: Fde A
authors.lastname: Kronemberger
authors.forename: Lidia Maria Melo
authors.initials: LM
authors.lastname: Santa Anna
authors.forename: Ana Carolina Loureiro Brito
authors.initials: AC
authors.lastname: Fernandes
authors.forename: Reginaldo Ramos de
authors.initials: RR
authors.lastname: Menezes
authors.forename: Cristiano Piacsek
authors.initials: CP
authors.lastname: Borges
authors.forename: Denise Maria Guimarães
authors.initials: DM
authors.lastname: Freire
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D010100:Oxygen / Q000378:metabolism*; D010865:Pilot Projects; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D013501:Surface-Active Agents / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D013501:Surface-Active Agents; D010100:Oxygen