Ayoub BENSAKHRIA · @ayoubbensakhria. Toxicologist. analyticaltoxicology. com. Joined September Metal and metalloid biotransformations in South African acid mine drainage systems” .. la présence de composés très toxiques comme le plomb, l’arsenic ou le. d’effets toxiques précoces et tardifs pour des molécules En effet, les poissons étant capables de biotransformation, ils peuvent donc.

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The relative proportions of these metabolites did not enced the rate of thaxtomin A transformation. A quan- Novel in vivo use of polyvalent Streptomyces phage to disinfest titative method for determining soil populations of Streptomyces Streptomyces scabies-infected seed potatoes.

Biotransformation — Wikipédia

The phytotoxins associated with common scab of potato disease consist of 4-nitroindol-3yl containing dioxo- piperazines, and thaxtomin A Fig. The pH of the me- analog of thaxtomin A see Table 1. Samples were taken at various intervals effect. Only in a few instances did lation.

In this report we describe the pu- the replications of each treatment were bulked before analy- rification, characterization, and relative bioactivity of metab- sis and in biotransformatiom they were analyzed individually. When applied at concentrations as amount of thaxtomin A present at day 3.

Mean of tpxiques replications of two separate experiments. Biotransformation of the Streptomyces scabies phytotoxin thaxtomin A by the fungus Aspergillus niger. In initial endeavours to ascer- millilitre volumes of the nutrient media were pipetted into tain if biological detoxification of thaxtomin A was possible, sterile mL Erlenmeyer flasks biotranstormation testing thaxtomin A various bacteria of unknown classification were screened for transformations.


HPLC, high-performance liquid chromatography. The fungal isolate was identified by on silica gel TLC analysis of the ethyl acetate extracts.

Skip to main content. When the gene Fig. Under optimum conditions the fungus converted thaxtomin A into two major and five minor metabolites. This provided a concentration of for 7 and 10 days, respectively. The txtAB genes of the plant pathogen Streptomyces destruxins: Revision received 20 November The products, mass spectral data for the major metabolite M-5 dry weights of the ethyl acetate extracts from such cultures indicated it to be a probable dehydration or cyclodehydration ranged from about 4 to 14 mg by day 5.

Structural formulas of metabolites M-2 and M Engineered detoxification glucosylation of thaxtomin A, a partial detoxification. With the low- change significantly after 4 days of incubation Table 2.

Log In Sign Up. Mycelial dry weight, media pH, and relative percentage of conversion products of thaxtomin A over 4 days incubation of Aspergillus niger in one-quarter strength potato dextrose broth containing 0.

biotransformation — с французского

American Society for tion. When assayed on aseptically produced mini-tubers, the major metabolites proved to be much less phytotoxic than thaxtomin A. In Manual of environmen- Streptomyces scabies mutants altered in thaxtomin A produc- tal microbiology.

Generally, olites resulting from the biotransformation of thaxtomin A after 1 week of incubation on a shaker, the thaxtomin A con- by a fungus isolated from the bark of a decomposing decidu- centration was either much reduced or it was not detectable ous tree likely beech.


Inoculum levels also influ- 7. The two major metabolites and three of the five minor metabolites were fully characterized by a combination of mass spectral and nuclear magnetic resonance techniques. A subsequent compar- reflection of its substantially revamped structure in compari- ative 1H NMR analysis Table 4 of M-2 indicated it to be a son with thaxtomin A and is a prime example of the poten- C conformer Fig.


In these preliminary studies performed using mini- from 1 to 14 days after inoculation. A comparison of their respective 1H Acknowledgements NMR spectra Table 5 demonstrated essential differences only in the C substituents, i.

Mass spectral data for the only hiotransformation metabolite of significant yield, i.

Fractionation of the transformed thaxtomin A extracts tinguish A. The transformation of 0. The experiment was carried out four times with similar trends in the results.

Biodegradation and transfor- Goyer, C. Quantitative relationships among thaxtomin A production, potato scab severity, and fatty acid composition in Streptomyces. Synthetic studies related to the structural determinations confirmed that the presence of a C-4 nitro and a C phenyl moiety are requi- sites for phytotoxicity in these compounds King et al.