Isolation and characterization of a novel simazine-degrading bacterium from agricultural soil of central Chile,Pseudomonassp. MHP41

Abstract

s-Triazine herbicides are used extensively in South America in agriculture and forestry. In this study, a bacterium designated as strain MHP41, capable of degrading simazine and atrazine, was isolated from agricultural soil in the Quillota valley, central Chile. Strain MHP41 is able to grow in minimal medium, using simazine as the sole nitrogen source. In this medium, the bacterium exhibited a growth rate of mu=0.10 h(-1), yielding a high biomass of 4.2 x 10(8) CFU mL(-1). Resting cells of strain MHP41 degrade more than 80% of simazine within 60 min. The atzA, atzB, atzC, atzD, atzE and atzF genes encoding the enzymes of the simazine upper and lower pathways were detected in strain MHP41. The motile Gram-negative bacterium was identified as a Pseudomonas sp., based on the Biolog microplate system and comparative sequence analyses of the 16S rRNA gene. Amplified ribosomal DNA restriction analysis allowed the differentiation of strain MHP41 from Pseudomonas sp. ADP. The comparative 16S rRNA gene sequence analyses suggested that strain MHP41 is closely related to Pseudomonas nitroreducens and Pseudomonas multiresinovorans. This is the first s-triazine-degrading bacterium isolated in South America. Strain MHP41 is a potential biocatalyst for the remediation of s-triazine-contaminated environments.

Bioaugmentation with Pseudomonas sp. strain MHP41 promotes simazine attenuation and bacterial community changes in agricultural soils

“…Allochthonous microorganisms that are reintroduced in soils show unsatisfactory bioremediation potential (Atlas & Unterman, 1999; Rousseaux et al , 2003). However, strain MHP41 is an autochthonous bacterium (Hernández et al , 2008). In this study, the use of an autochthonous bacterial strain, together with the encapsulation of cells in alginate (Vogel & Walter, 2002; Vancov et al , 2005), could explain the enhanced simazine removal rates in inoculated soils.…”

“…strain MHP41 was used to evaluate the bioaugmentation processes in agricultural soils contaminated with simazine. Strain MHP41 efficiently degrades simazine and is capable of growing rapidly using simazine as the sole nitrogen source, yielding a high biomass (Hernández et al , 2008). This strain possesses the s ‐triazine catabolic atzA , atzB , atzC , atzD , atzE and atzF genes.…”

Characterization of copper-resistant bacteria and bacterial communities from copper-polluted agricultural soils of central Chile

“…After decantation for 1 min, serial dilutions were prepared from the supernatant. The total cultivable heterotrophic bacteria were grown in R2A medium supplemented with cycloheximide (100 mg l -1 ) [29]. The Cu-tolerant bacteria were grown in same conditions supplemented with Cu 2+ (0.8 mM) [30].…”

Degradation of atrazine in mineral salts medium and soil using enrichment culture

“…Pseudomonas sp. strain MHP41, an efficient s-triazine-degrading bacterium, [10] has been successfully applied for bioremediation. [11] However, there are limitations in using pure cultures of microorganisms in remediation studies viz.…”