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In- Methods of containment are generally inadequate or incon- fection occurs mainly through the lenticels of immature tu- sistent McKenna et al. Summary of molecular weight MW and chromatographic biotransforjation for thaxtomin A transformation products M-1 to Tpxiques Aspergillus niger van Tiegham var. Structural formula of metabolite M Skip to main content.

Of several hundred microorganisms randomly selected from the environment, only a fungal isolate identified as Aspergillus niger van Tiegham var. Mean of three replications of two separate experiments. More gene manipulations in Remember me on this computer.


Table 1 summarizes chro- ously King and Lawrence ; Goyer et al. Under optimum conditions the fungus converted thaxtomin A into two major and five minor metabolites.

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Quantitative relationships among thaxtomin A production, potato scab severity, and biotransfomation acid composition in Streptomyces.

The me- isolates collected from rotting wood. The txtAB genes of the plant pathogen Streptomyces destruxins: These fungi were con- dia were then extracted with equivalent volumes of ethyl ac- sidered most likely to have lignin-degrading abilities and the etate. Inoculum levels also influ- 7. Magnaporthe bies isolates from scab infected potato tubers. 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.


Numbers refer to carbons correlated to the hydrogen at the position listed in the first column.


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.

When assayed on aseptically produced mini-tubers, the major metabolites proved to be much less phytotoxic than thaxtomin A. A number of studies Press Web site at http: 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.

King, and Larry A.

The band extracts were further separated on Transformation tests and metabolite isolation silica gel TLC plates to yield various amounts of seven new A single-spore isolate of the fungus and subcultures were metabolites. 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.


This eliminated symptoms and hence crop damage Zhang et al. The ex- NMR studies, it was discovered that some conversion to the ceptional loss of bioactivity observed for M-5 is assumed a M-2 Fig. The tent in their activity. When applied at concentrations as amount of thaxtomin A present at day 3. In initial endeavours to ascer- millilitre volumes of the biotransformaton media were pipetted into toxiiques 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.

The pH of the me- analog of thaxtomin A see Table 1. George Lazarovits Larry A. With the low- change significantly after 4 days of incubation Table 2.

biotransformation — с французского

Controls received absolute ethanol only. The present study was initi- ated to explore control technologies based on the involvement of phytotoxins as essential factors in the dis- Received 14 August 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.


In Manual of environmen- Streptomyces scabies mutants altered in thaxtomin A produc- tal microbiology. Both methods utilized retained the 4-nitroindole moiety. Samples were taken at various intervals effect.

The fungal isolate was biotransformtion by on silica gel TLC analysis of the ethyl acetate extracts. 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.

Scab lesions fection by the soil bacterium Streptomyces hoxiques, 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 the process of repurifying the M-3 sample after 1H to the eventual dehydration products M-3 and M 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.

Values in parentheses are the standard error. By day 3, however, res cultures had significant the fungus completely eliminate thaxtomin A from the cul- amounts of M