Rhamnolipid biosurfactant production by Pseudomonas nitroreducens immobilized on Ca2+ alginate beads and under resting cell condition

Abstract

Pseudomonas nitroreducens MILB-8054A isolated from petroleum-contaminated soil, immobilized on calcium alginate beads, and under resting cell condition, produced biosurfactants. Immobilized cells gave a best yield of 5.6 g rhamnolipid l−1 using sucrose as carbon source. Time course study using resting cells showed that 2 % v/v of palm oil (preculture carbon source) and 10 % diesel (carbon source) gave the best rhamnolipid yield of 5.1 g l−1 at pH 8 and temperature of 30 °C. Carbon utilization by resting cells was compared with that of growing cells. The best biosurfactant recovery procedure was acetone extraction.