[Isolation of an effective benzo [a] pyrene degrading strain and its degradation characteristics]

A strain which could utilize BaP as a sole carbon and energy source and efficiently degrade benzo[a] pyrene (BaP) was isolated from the contaminated sediments of Guiyu, Guangdong province, China. The strain was identified as Brevibacillus brevis based on physiological and biochemical experiments together with 16S rRNA sequence analysis. The experimental results showed that the biodegradation rate of BaP by B. brevis in 7 days was 51.35%. The study also demonstrated that pH, temperature, bacterial dosage, initial concentration of BaP and processing time were important factors for BaP degradation. B. brevis could tolerate wide pH and temperature ranges, from 2 to 12 degrees C and 25 to 40 degrees C, respectively. The optimum condition for BaP degradation was pH 7 and 25 degrees C. With the increase of B. brevis inoculation amount, the degradation efficacy displayed an initial increasing trend and then came to a plateau. And the increase of BaP concentration led to the enhancement of BaP degradation. Addition of salicylic, succinate and phthalate showed no obvious positive effect on BaP biodegradation. After degradation of BaP, the surface of B. brevis was wrinkled, and became depressed and deformed over time.