Detoxification of p-nitrophenol (PNP) using Enterococcus gallinarum JT-02 isolated from animal farm waste sludge

Enterococcus gallinarum (JT-02) isolated and identified from the animal farm waste sludge was found to be capable of biodegrading p-nitrophenol (PNP), an organic compound used to manufacture drugs, fungicides, insecticides, dyes, and to darken leather. The intention of this study was to optimize the biodegradation by finding the optimal conditions for the specific strain through single-factor experiments. The bacterial strain was grown in Luria Bertani broth and various parameters were optimized to achieve the prime settings for the p-nitrophenol (PNP) biodegradation. The results indicated that the best setups for the biodegradation by the strain JT-02 was 100 mg/L of PNP; pH 7; 30 degrees C; 150 rpm in a shaker incubator and 3% (v/v) of inoculum dose. Once the optimal conditions were found, the bacteria were capable of degrading p-nitrophenol (98.21%) in 4 days. Intermediates produced during PNP biodegradation were identified using High Performance Liquid Chromatography (HPLC) analysis and the biodegradation pathway was elucidated. Phytotoxicity studies were carried out with Vigna radiata seeds to confirm the applicability and efficiency of PNP biodegradation.

Automated summary

In this study, Enterococcus gallinarum (JT-02) was isolated and identified from animal farm waste sludge, showing the ability to biodegrade p-nitrophenol (PNP). The optimal conditions for PNP biodegradation by strain JT-02 were determined through single-factor experiments. It was found that the best setups included PNP concentration of 100 mg/L, pH 7, temperature of 30 degrees C, agitation speed of 150 rpm, and inoculum dose of 3% (v/v). Under these conditions, the bacteria degraded 98.21% of PNP within 4 days. The intermediates produced during PNP biodegradation were identified using High Performance Liquid Chromatography (HPLC) analysis, and the biodegradation pathway was elucidated. Phytotoxicity studies with Vigna radiata seeds confirmed the applicability and efficiency of PNP biodegradation.