Arthrobacter sp. strain KU001 isolated from a Thai soil degrades atrazine in the presence of inorganic nitrogen sources

Abstract

An atrazine degrading bacterium, strain KU001, was obtained from a sugarcane field at the Cane and Sugar Research and Development Center at the Kasetsart University, Kamphaeng Saen campus, Thailand. Strain KU001 had a rod-to-coccus morphological cycle during growth. Biolog carbon source analysis indicated that the isolated bacterium was Arthrobacter histidinolovorans. Sequence analysis of PCR product indicated the 16S rRNA gene in strain KU001 was 99% identical to the same region in Arthrobacter sp.. The atrazine degradation pathway in strain KU001 consists of the catabolic genes, trzN, atzB and, atzC. Strain KU001 was able to use atrazine as a sole nitrogen source for growth, and surprisingly, atrazine degradation was not inhibited in cells grown on ammonium, nitrate or urea, as compared to cells cultivated on growth-limiting nitrogen sources. During the atrazine degradation process, the supplementation of nitrate completely inhibits atrazine degradation activity in strain KU001, whereas ammonium and urea had no effect on atrazine degradation activity. The addition of strain KU001 to sterile or nonsterile soils resulted in the disappearance of atrazine at a rate that was 4 to 5-fold more than that achieved by the indigenous microbial community. The addition of citrate to soils resulted in enhanced atrazine degradation, 80% of atrazine disappeared within one day following nutrient supplementation.