Statistical optimization of the enzymatic breakdown of 2-Nitrophloroglucinol using thermo tolerant mixed Intracellular enzymes from Serratia marcescens

• Serratia marcescens, capable of degrading 2-nitrophloroglucinol (NPG) was isolated.
• Intracellular enzymes were extracted and characterized.
• Degradation of NPG was statistically optimized using Plackett–Burman & RSM design.
• The degradation products were identified by NMR spectroscopy and GC–MS analysis.

Serratia marcescens, capable of degrading 2-Nitrophloroglucinol (NPG), an endocrine disruptor, was isolated from the soil contaminated with tannery wastewater. The mixed intracellular enzymes (MICE) from S. marcescens were extracted and characterized. The activity of MICE was found to be the maximum at pH, 7 and at temperature, 40 ºC. The optimum conditions for degradation of NPG by thermo tolerant MICE were determined using Plackett–Burman design and response surface methodology. The maximum formation of pyruvic acid, the degradation end product was obtained at time, 3 h; pH, 7; temperature, 40 ºC; concentration of MICE, 4 mg and agitation speed, 75 rpm. The amount of pyruvic acid formed upon degradation (94.65%) of NPG from its initial value of 75 µg was 31.25 µg. The degradation of NPG by thermo tolerant MICE was found to be enhanced by the addition of metal ions such as Zn2+, Cu2+, Ca2+ and V3+ ions with complete conversion of NPG into pyruvic acid. The degradation of NPG by MICE was evaluated through UV–visible, fluorescence and Fourier Transform-Infra Red spectroscopy. The NPG degradation by MICE was confirmed using high pressure liquid chromatography, nuclear magnetic resonance and GC–MS spectroscopy.

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