Metabolic profiling of phenol biodegradation by an indigenous Rhodococcus pyridinivorans strain PDB9T N-1 isolated from paper pulp wastewater

In the present study, a phenol degrading actinomycetes strain was isolated from paper pulp wastewater. The isolated strain was identified as Rhodococcus pyridinivorans PDB9TN-1 using 16S rRNA gene sequencing technique, which yielded the complete degradation of 1600 mg l(-1) of phenol within 56 h. Moreover, the Rhodococcus species could remove over 97.5% of total organic carbon (TOC) at an initial phenol concentration of 1000 mg l(-1). The metabolic profile of phenol biodegradation by the actinomycetes species has been investigated using liquid chromatography-mass spectrometry (LC-MS) and Fourier-transform infrared spectroscopy (FT-IR). The key intermediate products detected in the actinomycetes culture were hydroquinone, protocatechuic acid, betacarboxycis-cismuconate, maleyl acetate, 4-oxalocrotonic acid and 3-fumarylpyruvic acid. Further, a tentative oxalocrotonic acid pathway has been proposed on the basis of the detected intermediate products. The culture medium constituents are highly indispensable for the microbial growth, enzyme and other cellular metabolic activities associated with phenol biodegradation. Therefore, the effect of media components were modelled with the help of response surface methodology (RSM) and central composite design (CCD). A reliable quadratic model was established which predicted the degradation efficiency as high as 99.5% with an appreciable correlation coefficient (R-2) of 0.98. Moreover, phenol degradation efficiency was improved with concentrations beyond the central values for all media components except K2HPO4 and NaCl.

Automated summary

A phenol-degrading actinomycetes strain, identified as Rhodococcus pyridinivorans PDB9TN-1, was isolated from paper pulp wastewater in this study. The strain was capable of completely degrading 1600 mg/L of phenol within 56 hours and removing over 97.5% of total organic carbon (TOC) at an initial phenol concentration of 1000 mg/L.