Biodegradation of benzo [a] pyrene by Rhodotorula sp. NS01 strain isolated from contaminated soil sample

Abstract

Microbial degradation provides a constructive approach to remove various toxic pollutants from the environment. There are reports on microorganisms as degraders of Benzo[a]pyrene (BaP), but very less report is available on yeast as potential degrader. Hence, the present work is focused on the isolation of yeast strain by a soil enrichment technique that possess the potentiality to degrade BaP. BaP is a high molecular weight polycyclic aromatic hydrocarbon (HMW PAHs) that has been considered as a harmful environmental persistent pollutant due to its high toxicity and carcinogenic nature. Molecular identification by 18S rRNA sequences revealed the isolate as, Rhodotorula sp. NS01. The course of the degradation was studied using Fourier transform infrared (FTIR) spectroscopy and high performance liquid chromatography (HPLC). The strain was found to utilize BaP as a sole carbon and energy source and efficiently degraded 52% of 10 mg/L of BaP within 7 days. The degradation data was tested with various kinetic models and the best fit was seen with first-order model with a calculated rate constant of 0.111 per day and a half-life period of 6.2 days. FTIR analysis revealed sharp peaks at 3388.93, 1724.36 and 1645.28 cm-1 corresponding to hydroxyl, aldehydes, ketones along with the reduction of C-C and C-H stretch in ring which confirmed the effective BaP biodegradation by Rhodotorola sp. NS01.