Valorization of phenol contaminated wastewater for lipid production by Rhodosporidium toruloides 9564.

Phenol is one of the most common hazardous organic compound presents in several industrial effluents which directly affects the aquatic environment. The present study envisaged the phenol biodegradation and simultaneous lipid production along with its underlying mechanism by oleaginous yeast Rhodosporidium toruloides 9564. Experiments were designed using simulated wastewater by varying phenol concentration in the range of 0.25-1.5 g/L and inoculum size of 1, 5, and 10% with and without glucose. The oleaginous yeast was found to completely degrade up to 0.75 g/L phenol with lipid accumulation of 26.3%. Phenol at > 0.5 g/L severely inhibited the growth of R. toruloides 9564 at 1% and 5% inoculum size. Phenol toxicity up to 0.75 g/L can be overcome by increasing inoculum size to 10%. The maximum specific growth rate (μ) and phenol degradation rate (q) were found to be 0.0717 h and 0.01523 h, respectively. The enzymatic pathway study suggested that R. toruloides 9564 follows an ortho cleavage pathway for phenol degradation and lipid accumulation. Phytotoxicty and cytotoxicity tests for treated and untreated samples clearly demonstrated a decline in toxicity of the treated wastewater. R. toruloides brought about an important paradigm shift toward a circular economy in which industrial wastewater is considered a valuable resource for bioenergy production.