Isolation and Identification of Two Degrading Strains in Atrazine Contaminated Soil

Two strains named W₇ and W₁₆ were isolated by liquid enrichment culture from the corn field where atrazine has been chronically applied. Observed by gram stain and SEM, W₇ belonged to gram-positive bacteria and the single cell was short bacilliform; W₁₆ belonged to gram-negative bacteria and the single cell was spherical. Through physiological and identification and 16SrDNA sequence analysis, two strains were identified as Rhizobium sp. and Rhodobacter sphaeroides sp. respectively. W₇ and W₁₆ could degrade atratine effectively, and the biodegradation rate reaching up to 99 % after 72 h cultivation in suitable conditions.