Rhamnolipid from Pseudomonas desmolyticum NCIM-2112 and its role in the degradation of Brown 3REL

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Abstract

The biosurfactant produced by Pseudomonas desmolyticum NCIM 2112 (Pd 2112) was confirmed as rhamnolipid based on the formation of dark blue halos around the colonies in CTAB-methylene blue agar plates and the content of rhamnose sugar. The average yield of rhamnolipid was 0.398 g/l/day when grown on hexadecane as sole carbon source. Pd 2112 emulsification potential associated with cell free culture broth was stable for 72 h using various hydrocarbons and vegetable oils. Chemical structure of the biosurfactant was identified as mono-rhamnolipid (Rha-C6–C8) using HPTLC, fourier transform infrared spectroscopy, 1H and 13C NMR and gas chromatography-mass spectroscopy analysis. Pd 2112 mono-rhamnolipid (1 mg/ml) had in-creased permeabilization of Bacillus sp VUS NCIM 5342 and increased decolorization rate of textile dye Brown 3REL by 50%. Extracellular activities of lignin peroxidase and veratryl alcohol oxidase, enzymes involved in dye degradation, were significantly increased in the presence of mono-rhamnolipid by 324.52% and 100% respectively. Scanning electron micro-scopy observations revealed that rhamnolipid did not exert any disruptive action on Bacillus cells as compared to Tween 80. The mono-rhamnolipid of Pd 2112 has potential for its application in biodegradation of textile dyes. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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