Enzyme-mediated biodegradation of long-chain n-alkanes (C32 and C40) by thermophilic bacteria

Punniyakotti Elumalai,Punniyakotti Parthipan,Aruliah Rajasekar,Obulisamy Parthiba Karthikeyan

doi:10.1007/s13205-017-0773-y

Punniyakotti Elumalai, Punniyakotti Parthipan + Show 2 more

Open Access

https://doi.org/10.1007/s13205-017-0773-y

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Abstract

Removal of long-chain hydrocarbons and n-alkanes from oil-contaminated environments are mere important to reduce the ecological damages, while bio-augmentation is a very promising technology that requires highly efficient microbes. In present study, the efficiency of pure isolates, i.e., Geobacillus thermoparaffinivorans IR2, Geobacillus stearothermophillus IR4 and Bacillus licheniformis MN6 and mixed consortium on degradation of long-chain n-alkanes C32 and C40 was investigated by batch cultivation test. Biodegradation efficiencies were found high for C32 by mixed consortium (90%) than pure strains, while the pure strains were better in degradation of C40 than mixed consortium (87%). In contrast, the maximum alkane hydroxylase activities (161 µmol mg−1 protein) were recorded in mixed consortium system that had supplied with C40 as sole carbon source. Also, the alcohol dehydrogenase (71 µmol mg−1 protein) and lipase activity (57 µmol mg−1 protein) were found high. Along with the enzyme activities, the hydrophobicity natures of the bacterial strains were found to determine the degradation efficiency of the hydrocarbons. Thus, the study suggested that the hydrophobicity of the bacteria is a critical parameter to understand the biodegradation of n-alkanes.

Highlights

Oil contamination and pollution is a global issue that poses threat to the ecology and environment (Hasanuzzaman et al 2007; Zhang et al 2012a; Kumar et al 2016)
Biodegradation efficiencies were found high for C32 by mixed consortium (90%) than pure strains, while the pure strains were better in degradation of C40 than mixed consortium (87%)
The present study aimed to investigate the biodegradation efficiency of pure isolates G. stearothermophilus IR4, G. thermoparaffinivorans IR2, B. licheniformis MN6 and as mixed consortium to remediate the C32 and C40, which are major pollutants from oilcontaminated environment

Summary

Introduction

Oil contamination and pollution is a global issue that poses threat to the ecology and environment (Hasanuzzaman et al 2007; Zhang et al 2012a; Kumar et al 2016). United States National Research Council classified these organic contaminants into high and low molecular weight hydrocarbons, oxygenated, halogenated aliphatics, aromatics, nitro aromatics hydrocarbons and alkanes (NRC 2000; Abrajano and Yan 2014). These hydrocarbons and alkanes have been considered as priority pollutants (NRC 2000; Ekperusi and Aigbodion 2015), which are biohazards and biomagnified in the environment (Kramer and Van der Heijden 1990; Mohamed et al 2006). Extensive research studies and reviews reported the biodegradation of the short chain hydrocarbons, while very limited studies reported the alkane and long-chain hydrocarbon degradations, 116 Page 2 of 10

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