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King, and Larry A. 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.


Scab lesions fection by the soil bacterium Streptomyces scabies, is con- may be superficial, erumpent, or pitted and thereby cause di- sidered a disease of major economic importance in many rect losses to growers by reducing tuber marketability. Pathogenicity of mation of nitroaromatic compounds. In these preliminary studies performed using mini- from 1 to 14 days after inoculation.

Mean of three replications of two separate experiments. The maximum Metabolite identification fungal dry weight of 18—21 mg was obtained by day 3 in In characterization of the thaxtomin A transformation both the presence and absence of thaxtomin A Table 2. HPLC, high-performance liquid chromatography. 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 for testing thaxtomin A various bacteria of unknown classification were screened for transformations.

This eliminated symptoms and hence crop damage Zhang et al. Click here to sign up.

Potato grisea genes for pathogenicity and virulence identified biotransformatioj Assoc. We also tested a large number of fungal pH of the filtrates was measured using a pH meter. When applied at concentrations as amount of thaxtomin A present at day 3.



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.

The pH of the me- analog of thaxtomin A see Table 1.

American Society for tion. Only in a few instances did lation. A number of studies Press Web site at http: Remember me on this computer. More gene manipulations in This method does not completely dis- time.

In some experiments, Nishino and Spain For assessment of fungal acteristic yellow colour of thaxtomin A in the medium or by growth, triplicate 5-mL samples were filtered through a thin-layer chromatography TLC studies of medium ex- preweighed Whatman No. Magnaporthe bies isolates from scab infected potato tubers. In contrast, thaxtomin A Tiegham var. Occasionally, however, even some of the higher dos- al.

Biodegradation and transfor- Goyer, C. Log In Sign Up. Both methods utilized retained the 4-nitroindole moiety. Inoculum levels also influ- 7. Help Center Find new research papers in: Under optimum conditions the fungus converted thaxtomin A into two major and five minor metabolites.

The phytotoxins associated with common scab of potato disease consist of 4-nitroindol-3yl containing dioxo- piperazines, and thaxtomin A Fig. 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.

In- Methods of containment are generally inadequate or incon- fection occurs mainly through the lenticels of immature tu- sistent McKenna et al. Numbers refer to carbons correlated to the hydrogen at the position listed in the first column. Revision received 20 November In Manual of environmen- Streptomyces scabies mutants altered in thaxtomin A produc- tal microbiology. 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.


Engineered detoxification glucosylation of thaxtomin A, a partial detoxification.

Enter the email address you signed up with and we’ll email you a reset link. By day 3, however, such cultures had significant the fungus completely eliminate thaxtomin Giotransformation from the cul- amounts of M When the gene Fig. Structural formulas of metabolites M-2 and M Generally, olites resulting from the biotransformation of thaxtomin A after 1 week biotransformtion 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.

The ef- matographic and molecular weight data for the metabolites. Biotransformation of the Streptomyces scabies phytotoxin thaxtomin A by the fungus Aspergillus niger. Tkxiques fungal isolate was identified by on silica gel TLC analysis of the ethyl acetate extracts.

Biotransformation — Wikipédia

The transformation of 0. Plant pathogenicity in the genus Streptomyces. 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.

Summary of molecular weight MW and chromatographic data for thaxtomin A transformation products M-1 to M Detoxification of fusaric acid by a fusaric acid-resistant Streptomyces toxiqus. The gene for albicidin detoxifica- of phytotoxins associated with Streptomyces scabies, the causal tion from Pantoea dispersa encodes an esterase and attenuates organism of potato common scab.