Biodegradation of p-nitrophenol by Immobilized Rhodococcus sp. Strain Y-1

Z. Leilei, H. Mingxin and Z. Suiyi

Abstract
A high efficiency p-nitrophenol (PNP) degrading bacterial strain Y-1 capable of utilizing PNP as sole carbon and energy source was screened and isolated from the activated sludge of Jilin Chemical Plant Oxidation Ditch in China. 16S rDNA sequencing identified strain Y-1 to be Rhodococcus sp. Polyvinyl alcohol (PVA) and sodium alginate were employed to immobilize the Rhodococcus sp. strain Y-1. Compared to the free cells, the immobilized cells possessed better PNP-degrading activity and stronger tolerance against the inhibitory effect of PNP. An orthogonal experimental design of L9 (34) was used to investigate the effects of temperature, pH, and agitation rate on the biodegradation capabilities of the immobilized cells; the optimum conditions were as follows: 30 °C, pH at 7.0–7.5, shaken at 120 rpm. Moreover, immobilization supplemented with 1 g Fe3O4 significantly enhanced the PNP degradation capability (up to 500 mg L–1). Our results indicated that immobilized Rhodococcus sp. strain Y-1 possessed good potential for application in the treatment of wastewater containing PNP.

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Keywords
PNP, biodegradation, Rhodococcus sp. strain Y-1, immobilized bacterium, Fe3O4