J. Biol. Chem. Environ. Sci., 9(3):383-400., 2014 J. Biol. Chem. Environ. Sci., 9(3):383-400., 2014 1 Biodegradation of pendimethalin residues by P. chrysosporium in aquatic system and soils Belal E. B. and Nagwa M. Elkhateeb Agricultural Botany Dept., (Agricultural Microbiology) Faculty of Agriculture, Kafrelsheikh Univ., 33516, Kafr El-Sheikh, Egypt. ABSTRACT This work was conducted to investigate the pendimethalin biodegradation by Phanerochaete chrysosporium in aquatic system and different types from soils. P. chrysosporium biomass and atrazine degradation were found to be optimum at pH 7 and 30 °C. Additional carbon sources (i.e., glucose, mannitol and phenol) and nitrogen sources (i.e., ammonium sulfate and sodium nitrate) decreased pendimethalin degradation. P. chrysosporium was able to dissipate 95% pendimethalin in liquid medium at pH 7 and 30 °C after 28 days and its half-life was 6.44 days compared to 53.9 days in uninoculated medium. Results showed also that pendimethalin was degraded faster by P. chrysosporium in sandy soil than clay soil compared to their respective uninoculated soils after 28 days and their half-lives were 4.4, 8.4, 62.43 and 64.7 days, respectively. The degradation of pendimethalin was coinciding with increasing microbial biomass in both pendimethalin contaminated soils comparing with control treatments. This study has shown that P. chrysosporium could be applied to remediate pendimethalin contaminated water and soils. Keyword: Pendimethalin, Water, Soil, Biodegradation. INTRODUCTION Pendimethalin (N-(1-ethylpropyl)-2, 6-dinitro-3,4-xylidine) has the empirical formula C 13 H 19 N 3 O 4 , a selective pre-emergent herbicide a dinitroaniline group, is used extensively for weed control in cotton, rice, soybean and tobacco (Smith et al., 1995). Pendimethalin acts by inhibiting the steps in plant cell division responsible for chromosome separation and cell wall formation. It is used before crop emergence or planting (Appleby and Valverde, 1988). The inhibition of root and shoot growth results in stunting of aerial plant portions (El-Nady and Belal 2013). Studies in terrestrial ecosystems showed that 10–20% of the herbicide vaporizes within the first week or two week after application