Medium optimization for a novel crude-oil degrading lipase fromPseudomonas aeruginosa SL-72 using statistical approaches for bioremediation of crude-oil

 

Shikha Verma^a,Jyoti Saxena^b,Radha Prasanna^c,Vinay Sharma^a,Lata Nain^c,

                                                                                                                     

Abstract

A meso-alkaliphilic strain of Pseudomonas aeruginosa SL-72 was isolated from the soil contaminated with the effluents from mustard-oil plant. Statistical tools were employed to optimize the medium constituents to enhance lipase-yield. Plackett–Burman design evaluated the effect of six medium constituents which significantly influence lipase-production, cell growth and microbial activity. Variance of analysis (ANOVA) showed that Tween-80, (NH₄)₂HPO₄ and MgSO₄·7H₂O were the most significant variables (p<0.05). Further, Central Composite Design (CCD) was used to optimize the most significant medium constituents and the optimum values estimated by multiple response optimization were 0.5% Tween-80, 1.0% (NH₄)₂HPO₄, and 0.1% MgSO₄·7H₂O, with a predicted value of 5038.86 IU ml⁻¹ lipase-production. Evaluation in a fermenter using the optimized medium constituents resulted in an approximately 1.59-fold increase over the central-point (3155.24 IU ml⁻¹) and 3.68-fold increase under unoptimized culture conditions (1376.60 IU ml⁻¹). This strain had also effectively degraded 82.83% crude-oil within a week, for safe disposal of wastewater.

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Keywords

• Crude oil;Lipase; Pseudomonas aeruginosa; Medium optimization; Response surface methodology