Simazine degradation by immobilized and suspended soil bacterium

Martin-Montalvo, Diego; Mengs, Gerardo; Ferrer, Esther; Allende, J.L.; Alonso, Ramón; Martín, Margarita

doi:10.1016/s0964-8305(97)00049-8

Cited by 13 publications

(10 citation statements)

References 14 publications

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“…Immobilization by adsorption, the gentlest fixation method, is mainly suitable for viable cells, compared to the immobilization of cells by entrapment into organic polymer (3). Previous studies demonstrated that the tolerance of various bacterial species to different organic compounds (3,5,12,21) could be elevated by cell immobilization. Heipieper et al (8) reported that phenol at sublethal concentrations is less inhibitory to immobilized microorganisms than to free microorganisms.…”

Section: Discussionmentioning

confidence: 99%

“…A ceramic material, granular sepiolite, was chosen as the support; the immobilization method used has been previously described (3,5,12). This porous material was placed into MB (10 g of sepiolite/20 ml of MB) and autoclaved; after 24 h, the mineral medium was replaced by a new sterile medium.…”

Section: Methodsmentioning

confidence: 99%

“…The relatively new concept of bioremediation provides a potentially cheap alternative to traditional disposal techniques, in addition to representing a genuine removal of contaminants by microbial degradation rather than the relocation of contaminants in such processes as landfilling. The problems presented by continuous fermentation processes could be resolved by the use of immobilized cells as biocatalysts (5,7,12,21).The aim of this study was to characterize the propachlor metabolism of a strain (GCH1) isolated from soil and to test a bioremediation system using immobilized cells in a reactor operating over a period of 150 days. The kinetics of the degradation and the viability of the immobilized cells are reported.…”

mentioning

confidence: 99%

“…Cells grown in 0.5 mM propachlor were harvested at the exponential phase and used as the inoculum. Immobilized cells were examined by scanning electron microscopy as previously reported (3,12).Use and mineralization of propachlor. Kinetic parameters for the mineralization of propachlor were determined as previously reported (11).…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Propachlor Removal by Pseudomonas Strain GCH1 in an Immobilized-Cell System

Martín

Mengs

Płaza

et al. 2000

Appl Environ Microbiol

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A bacterial strain capable of growing on propachlor (2-chloro-N-isopropylacetanilide) was isolated from soil by using enrichment and isolation techniques. The strain isolated, designated GCH1, was classified as a member of the genus Pseudomonas. Washed-cell suspensions of strain GCH1 accumulated N-isopropylacetanilide, acetanilide, acetamide, and catechol. Pseudomonas strain GCH1 grew on propachlor with a generation time of 4.2 h and a rate of substrate utilization of 1.75 ؎ 0.15 mol h ؊1 . Gene expression did not require induction but was subject to catabolite expression. Acetanilide was a growth substrate with a yield of 0.56 ؎ 0.02 mg of protein mol ؊1 . GCH1 strain cells were immobilized by adsorption onto a ceramic support and were used as biocatalysts in an immobilized cell system. Propachlor elimination reached 98%, with a retention time of 3 h and an initial organic load of 0.5 mM propachlor. The viability of immobilized cells increased 34-fold after 120 days of bioreactor operation.Propachlor (2-chloro-N-isopropylacetanilide) is an acylanilide herbicide widely used with corn, onion, cabbage, rose bushes, and ornamental plants. Microbial degradation (11,15,16,19) is the primary mechanism of acylanilide dissipation from soil. We previously reported the isolation of Pseudomonas strain PEM1 (3, 10, 11), which metabolizes the herbicide propachlor, yielding N-isopropylacetanilide, acetanilide, and acetamide as intermediates, and the isolation of Acinetobacter strain BEM2, which follows a different pathway and yields N-isopropylaniline and isopropylamine as intermediates. Lee et al. (9) reported that N-isopropylaniline, N-isopropylacetanilide, N-(1-hydroxyisopropyl)acetanilide, and N-isopropyl-2-acetoxyacetanilide were formed in soil treated with propachlor. Villareal et al. (18) proposed a propachlor degradative pathway yielding 2-chloro-N-isopropylacetamide and catechol as intermediates.Groundwater and soil contamination by herbicides has recently become of increasing concern (6,7,20). The relatively new concept of bioremediation provides a potentially cheap alternative to traditional disposal techniques, in addition to representing a genuine removal of contaminants by microbial degradation rather than the relocation of contaminants in such processes as landfilling. The problems presented by continuous fermentation processes could be resolved by the use of immobilized cells as biocatalysts (5,7,12,21).The aim of this study was to characterize the propachlor metabolism of a strain (GCH1) isolated from soil and to test a bioremediation system using immobilized cells in a reactor operating over a period of 150 days. The kinetics of the degradation and the viability of the immobilized cells are reported. MATERIALS AND METHODSIsolation of bacteria. Ten soil samples (10) were collected from agricultural fields in Madrid, Spain, with a history of propachlor contamination. Minimal medium (MB) (4) supplemented with 45 mg of propachlor liter Ϫ1 was inoculated with 20 g of soil sample and incubated at 28°C without sh...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Propachlor Removal by Pseudomonas Strain GCH1 in an Immobilized-Cell System

Martín

Mengs

Płaza

et al. 2000

Appl Environ Microbiol

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Simazine biodegradation in soil: analysis of bacterial community structure by in situ hybridization

Caracciolo

Grenni

Ciccoli³

et al. 2005

Pest Management Science

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Pesticide and nitrate contamination of soil and groundwater from agriculture is an environmental and public health concern worldwide. Simazine, 6-chloro-N2,N4-diethyl-1,3,5-triazine-2,4-diamine, is a triazine herbicide used in agriculture for selective weed control with several types of crops and it is frequently applied to soils receiving N-fertilizers. Degradation experiments were performed in the laboratory to assess whether the biodegradation of simazine in soil may be influenced by the presence of urea. Simazine degradation rates under different experimental conditions (presence/absence of urea, microbiologically active/sterilized soil) were assessed together with the formation, degradation and transformation of its main metabolites in soil. Simazine degradation was affected by the presence of urea, in terms both of a smaller half-life (t(1/2)) and of a higher amount of desethyl-simazine formed. The soil bacterial community was also studied. Microbial abundances were determined by epifluorescence direct counting. Moreover in situ hybridization with rRNA-targeted fluorescent oligonucleotide probes was used to analyze the bacterial community structure. Fluorescent in situ hybridization (FISH) was used to detect specific groups of bacteria such as the alpha,beta,gamma-subdivisions of Proteobacteria, Gram-positive bacteria with a high G + C DNA content, Planctomycetes, Betaproteobacterial ammonia-oxidizing bacteria and nitrifying bacteria. The presence of the herbicide and/or urea affected the bacterial community structure, showing that FISH is a valuable tool for determining the response of bacterial populations to different environmental conditions.

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Bioremediation of Soil Ecosystems from Triazine Herbicides

Caracciolo

Grenni

2021

The Handbook of Environmental Chemistry

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Simazine degradation by immobilized and suspended soil bacterium

Cited by 13 publications

References 14 publications

Propachlor Removal by Pseudomonas Strain GCH1 in an Immobilized-Cell System

Propachlor Removal by Pseudomonas Strain GCH1 in an Immobilized-Cell System

Simazine biodegradation in soil: analysis of bacterial community structure by in situ hybridization

Bioremediation of Soil Ecosystems from Triazine Herbicides

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