Fluorescent pseudomonas isolates from Mississippi Delta oxbow lakes: In vitro herbicide biotransformations

Abstract

Fluorescent pseudomonads were a major component [log (10) 4.2-6.1 colony-forming units mL-1] of the culturable heterotrophic gram-negative bacterioplankton observed in three Mississippi Delta oxbow lakes in this study. Pure cultures of fluorescent pseudomonads were isolated from three Mississippi Delta oxbow lakes (18 per lake), using selective media S-1. Classical physiological tests and Biolog GN plates were used in criteria for taxonomic identification. Most isolates were identified as biotypes of Pseudomonas fluorescens 55% (II), 7% (III), and 25% (V). About 7% of the isolates were identified as P. putida and 7% as non-fluorescent Pseudomonas-like. Cell suspensions of these isolates were tested for their ability to metabolize/co-metabolize six 14C-radiolabeled herbicides (2,4-dichlorophenoxyacetic acid (2,4-D), cyanazine, fluometuron, metolachlor, propanil, and trifluralin) that are commonly used for crop production in this geographical area. Almost all (53 of 54) isolates transformed trifluralin via aromatic nitroreduction. Most isolates (70%) dechlorinated metolachlor to polar metabolites via glutathione conjugation. About 60% of the isolates hydrolyzed the amide bond of propanil (a rice herbicide) to dichloroaniline, with the highest frequency of propanil-hydrolyzing isolates observed in the lake from the watershed with rice cultivation. All propanil-hydrolyzing isolates were identified as P. fluorescens biotype II. No metabolism of cyanazine or fluometuron was observed by any isolates tested, indicating little or no potential for N-dealkylation among this group of bacterioplankton. No mineralization of 2,4-D labeled in either the carboxyl or ring position was observed. These results indicate that reductive and hydrolytic pathways for herbicide co-metabolism (aromatic nitroreduction, aryl acylamidase, and glutathione conjugation) are common in Mississippi Delta aquatic fluorescent pseudomonads; however, the potential for certain oxidative transformations (N-dealkylation, cyano group oxidation) may be rare in this group of bacterioplankton.

Diversity of propanil-degrading bacteria isolated from rice rhizosphere and their potential for plant growth promotion

“…Although additional experiments are necessary to analyze these potential properties of the recombinant strain, it is known that Pseudomonas spp are the most abundant rhizosphere species (Silby et al, 2009). van Overbeek et al (1997 found that a Pseudomonas strain carrying reporter genes colonized the wheat rhizosphere, and several successful rhizoremediation experiments have been carried out with Pseudomonas strains to clean up soils that are polluted with propanil (Zablotowicz et al, 2001). Monti et al (2005) showed the possibility of assessing the ecology of inoculants in the rhizosphere by studying differential reporter gene expression and adaptability under field conditions.…”

Biodegradação Do Herbicida Propanil Por Fungo Isolado Da Rizosfera De Arroz

“…Várias bactérias, algumas isoladas de cultivo de arroz, foram selecionadas pela capacidade de degradar cloroanilinas, tais como Comamonas testosteroni (BOON et al, 2000), Pseudomonas acidovorans BN3.1 (BRUNSBACH e REINEKE, 1993), Proteus mirabilis (CORREA e STEEN, 1995), Aquaspirillum sp e Paracoccus denitrificans 3CA (SUROVTSEVA et al, 1996). A bactéria Pseudomonas fluorescens biotipo II hidrolisou propanil à 3,4-DCA (ZABLOTOWICZ et al, 2001).…”

Disposable Biosensor Based on Amidase/CeO2/GNR Modified Inkjet‐printed CNT Electrodes‐droplet Based Paracetamol Detection in Biological Fluids for “Point‐of‐care” Applications

“…Aryl acylamidase catalyzes hydrolysis of amide bond between aryl and acyl moieties, and are present in both Prokaryotes and Eukaryotes. Bacterial aryl acylamidases have been exploited in various biotechnological applications including the biodegradation of xenobiotic herbicides in bioremediation but they also find application in the detection of p‐acetaminophenol in clinical tests. The catalysis of non‐peptide amide bonds in the bioassay of p‐acetaminophenol in biological samples has been proposed aryl acylamidase as a template for a biosensor system .…”