Persistence and distribution of pesticide residues in fresh agricultural food consumed in the province of Bologna.

Strain XA05 and FG03 with high biodegradation activity of phenol were isolated from the activated sludge and phenol-contaminated soils in Northwest of China, respectively. DNA sequencing and homologous analysis of 16s rRNA gene identified that XA05 belonged to an Acinetobacter sp. and FG03 was closely related to the Sphingomonas sp. Cells of strain XA05 and FG03 were mixed at the ratio of 1:1, and polyvinyl alcohol (PVA) was used as a gel matrix to immobilize mixed cells by repeated freezing and thawing. Biodegradation was evaluated by determining phenol. Detoxication was evaluated by using Daphnia magna toxicity tests. The removal effciency of phenol and factors affecting phenol degradation were investigated, the stability of the immobilized cells was also reported. Experimental values indicated that both free cells and immobilized cells showed high phenol degradation effciencies, higher than 95% within 35 h with an initial concentration of 800 mg/L phenol, and the immobilized cells showed better performance than that of the suspended-culture cells. These results indicate that immobilized Acinetobncter sp. XA05 and Sphingomonas sp. FG03 possesses a good application potential in the treatment of phenol-containing wastewater.