Biodegradation of Phenol by Rhodococcus sp. Strain SKC: Characterization and Kinetics Study.

Chaofan Li,Yujuan Wen,Yuesuo Yang,Xiaoming Song

doi:10.3390/molecules25163665

Chaofan Li, Yujuan Wen + Show 2 more

Open Access

https://doi.org/10.3390/molecules25163665

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Abstract

This study focuses on the kinetics of a pure strain of bacterium Rhodococcus sp. SKC, isolated from phenol-contaminated soil, for the biodegradation of phenol as its sole carbon and energy source in aqueous medium. The kinetics of phenol biodegradation including the lag phase, the maximum phenol degradation rate, maximum growth rate (Rm) and maximum yield coefficient (Y) for each Si (initial phenol concentration, mg/L) were fitted using the Gompertz and Haldane models of substrate inhibition (R2 > 0.9904, RMSE < 0.00925). The values of these parameters at optimum conditions were μmax = 0.30 h−1, Ks = 36.40 mg/L, and Ki = 418.79 mg/L, and that means the inhibition concentration of phenol was 418.79 mg/L. By comparing with other strains of bacteria, Rhodococcus sp. SKC exhibited a high yield factor and tolerance towards phenol. This study demonstrates the potential application of Rhodococcus sp. SKC for the bioremediation of phenol contaminate.

Highlights

Phenol is a protoplasmic toxin that is common in industrial waste water, originating from coking plants, dyes, varnishes, pharmaceuticals, and pesticides [1]
SKC was isolated from phenol-polluted soil and classified as Gram-positive bacteria
The similarity BLAST results indicate that the strain was closely related to Rhodococcus sp. with 99% sequence identity

Summary

Introduction

Phenol is a protoplasmic toxin that is common in industrial waste water, originating from coking plants, dyes, varnishes, pharmaceuticals, and pesticides [1]. To the best of our knowledge, only a few studies have evaluated bacterial growth models and the degradation kinetics of phenol with Rhodococcus sp. We isolated a strain which could degrade phenol at a higher concentration and provide a comprehensive evaluation of the degrading characteristic of Rhodococcus sp. The parameters, μmax (the maximum specific biomass growth rate), Ks (saturation constant for substrate), Rm (maximum growth rate), λ (lag time), and Y (maximum yield coefficient) were subsequently calculated and compared with other microorganisms, as these parameters play key roles in the effective design of biological methods to treat phenol contaminate (ground water, sanitary waste water)

Results and Discussion

Biodegradation of Phenol as the Sole Carbon Substrate

Effect of Temperature and Initial pH Value on Phenol Biodegradation

The Growth Kinetics

Fitting

The Substrate-Inhibition Model

Yield Factor

Chemicals

Isolation and Identification of Strain

Experimental

Analytical Methods

Conclusions