Biosurfactant production by free and alginate entrapped cells of Pseudomonas fluorescens

Abstract

Production of biosurfactant by free and alginate-entrapped cells of Pseudomonas fluorescens Migula 1895-DSMZ was investigated using olive oil as the sole carbon and energy source. Biosurfactant synthesis was followed by measuring surface tension and emulsifying index E24 over 5 days at ambient temperature and at neutral pH. Diffusional limitations in alginate beads affected the kinetics of biosurfactant production when compared to that obtained with free cells culture. Nevertheless, the emulsion stability was improved and fewer by-products interfered with the biosurfactant activity. A decrease in pH down to 5 in the case of immobilized cells was observed during the first 3 days, after which it returned to its initial value. The minimum values of surface tension were 30 and 35 dynes cm(-1) achieved after 40 and 72 h with free and immobilized cells, respectively, while the corresponding maximum E24 values were 67 and 62%, respectively. After separation by acetone precipitation, the biosurfactant showed a rhamnolipid-type in nature, and had a good foaming and emulsifying activities. The critical micellar concentration was found to be 290 mg l(-1). The biosurfactant also showed good stability during exposure to high temperatures (up to 120 degrees C for 15 min), to high salinity (10% NaCl) and to a wide range of pH (4-9).

Biosurfactant Production by Pseudomonas aeruginosa BN10 Cells Entrapped in Cryogels

“…The observed delay in biosurfactant production could be due to some mass transfer limitations. On the other hand, the optimal production of rhamnolipids (4.6 g l -1 ) clearly showed that the immobilization procedure led to greater physiological stability of the cells as reported by other authors (Abouseoud et al, 2008).…”

“…It was also demonstrated that the entrapment of the marine bacterium Pseudomonas aeruginosa BYK-2 in 10% poly(vinyl alcohol) beads yielded 0.1 g rhamnolipid per hour in an airlift bioreactor (Jeong et al, 2004). Furthermore, the capacity for rhamnolipid production by both free and alginate-entrapped cells of Pseudomonas fl uorescence was investigated in batch cultures, and it was confi rmed that immobilization increased the biosurfactant recovery (Abouseoud et al, 2008). Heydl et al (2011) reported a new integrated process for continuous rhamnolipid production by Pseudomonas aeruginosa DSM 2874 entrapped in magnetic alginate beads, reaching a fi nal amount of 70 g rhamnolipid after four production cycles in a 10-l bioreactor.…”

EXTRACCIÓN DE PETRÓLEO EN SUELO CONTAMINADO EMPLEANDO RAMNOLÍPIDOS PRODUCIDOS POR Pseudomonas aeruginosa ORA9

“…La temperatura máxima evaluada en este trabajo fue 100 ºC, sin embargo, se ha demostrado que los ramnolípidos pueden ser estables a mayores temperaturas. Así, los producidos por Pseudomonas fluorescens fueron estables de 25 a 120 ºC (Abouseoud et al 2008).…”

“…Con resultados similares, Abdel et al (2009) muestran la actividad superficial estable hasta los 30 g/L para una variación de la tensión superficial desde los 33 hasta los 37 mN/m de una disolución de 50 g/L de ramnolípidos purificados. Estos resultados de estabilidad son inferiores al obtenido para los ramnolípidos producidos por Pseudomonas aeruginosa ORA9, no obstante, Abouseoud et al (2008) reportan la estabilidad de la tensión superficial de una solución de ramnolípidos purificados hasta los 150 g/L de cloruro de sodio en el medio.…”

Biodegradation of Linear Alkylbenzene Sulfonate (LAS) by Immobilized <i>Pseudomonas</i> sp.

“…The modified culture medium for the immobilized cells contained (g•l −1 of distilled water) K 2 HPO 4 (0.2), KH 2 PO 4 (0.1), CaCl 2 (0.01) [13].…”