Abstract
The present study was conducted to statistically optimize the biosurfactant production yield of Pseudomonas sp. F5 using raw orange peel extract (Central composite design (CCD) design; Surface tension (ST) reduction=32.41dyne/cm; biosurfactant yield=~2.4g/L). The extracted biosurfactant was characterized as a glycolipid having predominant mono-rhamnolipids than di-rhamnolipids with a critical micelle concentration (CMC) of 40mg/L. The potential of strain F5 for good biosurfactant yield during Pb2+ stress and the inherent mechanism for simultaneous biosorption of Pb2+ was also investigated. During concomitant submerged fermentation from 100 to 500mg/L of Pb2+ showed enhancement in adsorption capacity from 99.44 to 267.86mg/g respectively having 60.33±2.87 of emulsification index (E24%) measured at 100mg/L Pb2+ corresponding to maximum biosurfactant production during metal stress. The bacterium showed a high Pb2+ MIC (minimum inhibitory concentration) of 2200mg/L and efficiently biosorbed Pb2+ ions at pH 7 and a dosage of 0.05g under varying initial metal ion concentration and contact time. The exothermic biosorption (chemisorption) mechanism was found to be fitted well with Langmuir (R2=0.9859) and Pseudo second-order kinetic model (R2=0.9975; 200mg/L) having a maximum adsorption capacity of 294.12mg/g. These findings indicated the excellent potential of biosurfactant producing strain F5 in the removal of Pb2+ ions from aqueous system and management of agrowastes as suitable carbon substrate.
Published Version
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