THE ATRAZINE HYDROLASE GENE TRZN FROM NOCARDIODES SP. C190: CLONING AND CONSTRUCTION OF GENE-SPECIFIC PRIMERS

Authors: Mulbry, Walter; ZHUG, HONG - AGRIC & AGRI-FOOD CANADA; NOUR, SARAH - AGRIC & AGRI-FOOD CANADA; TOPP, EDWARD - AGRIC & AGRI-FOOD CANADA

Submitted to: Federation of European Microbiological Societies Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2001
Publication Date: 2/24/2002
Citation: MULBRY III, W.W., ZHUG, H., NOUR, S.M., TOPP, E. THE ATRAZINE HYDROLASE GENE TRZN FROM NOCARDIODES SP. C190: CLONING AND CONSTRUCTION OF GENE-SPECIFIC PRIMERS. FEDERATION OF EUROPEAN MICROBIOLOGICAL SOCIETIES MICROBIOL LETTERS. 2002.

Interpretive Summary: The widespread use and relative persistence of s-triazine herbicides such as atrazine has lead to increasing concern about surface and groundwater contamination by these compounds. Alkylated s-triazine compounds such as atrazine are relatively recalcitrant to biodegradation processes in soil. Few microorganisms have been isolated that degrade these compounds at rates that would be useful for detoxifying pesticide wastes. In this study, scientists isolated and characterized a bacterial gene that is responsible for an unusual enzyme that removes chlorines from atrazine and other s-triazines herbicides. They then designed DNA sequences to be used to probe soils for the presence of other bacteria containing this gene. The use of such DNA probes will help scientists understand how soil microorganisms adapt to break down agrochemicals and how these traits are transferred among the soil microflora.

Technical Abstract: Using oligonucleotides derived from the N-terminal sequence of a triazine hydrolase from Nocardioides sp. strain C190, two DNA fragments containing trzN were cloned into Escherichia coli and their nucleotide sequences were determined. The 456 amino acid polypeptide predicted from the 1356-bp trzN ORF displayed significant similarity to triazine hydrolases from Pseudomonas and Rhodococcus isolates and belonged to the same amidohydrolase family. The trzN gene was flanked by two DNA sequences possessing 57% and 69% identity, respectively, at the protein level to Rhodococcus erythropolis sequences for a transposase and a transposase helper protein. Amplification primers specific to trzN were tested in soils inoculated with strain C190. The results demonstrated that the primers were specific to trzN, and could detect populations at 108 cfu/g soil using 250 mg soil samples.