Strains of Rhizobium meliloti, Rhizobium sp. nodulating cowpeas, and R. phaseoli derived from cultures susceptible to tetramethylthiuram disulfide (thiram), 2,3-dichloro-1,4-naphthoquinone (phygon), and 2,3,5,6-tetrachloro-p-benzoquinone (spergon), respectively, grew in the presence of high concentrations of the fungicides and converted them to products not toxic to the sensitive rhizobia. The results of chemical assays demonstrated that the pesticides were destroyed by the resistant bacteria but not by the susceptible parent rhizobia. Resting cells of thiram-metabolizing R. meliloti formed large quantities of dimethyldithiocarbamate, dimethylamine, and CS2 from the pesticide. The products were characterized by gas and thin-layer chromatography, colorimetric reactions, and ultraviolet spectrometry. Dimethylamine and CS2 were formed spontaneously from dimethyldithiocarbamate, but the yield was higher in the presence of R. meliloti. The phygon-resistant bacterium converted the fungicide to five metabolites and thereby rendered the chemical nontoxic to a test fungus. The resistant strain of R. phaseoli generated at least one organic product and released about one-third of the chlorine during its detoxication of spergon.

Report on Tetramethylthiuram Disulfide

Resistance of Rhizobium strains to phygon, spergon, and thiram.

Wahrend die starke Zunahme der Weltbevolkerung um jahrlich etwa 1%, das sind etwa 20 Millionen Menschen, zu einer stets intensiveren landwirtschaftlichen Nutzung und Sicherung der Ernten wie auch einer Ausdehnung der Vorratshaltung zwingen, vernichten nach Schatzungen der Weltgesundheitsorganisation tierische Schadlinge und Pflanzenkrankheiten bis zu 1/5 der Welternte. Eine aus­reichende Ernahrung der Menschheit ist daher ohne intensiven Pflanzen- und Vorratsschutz nicht denkbar. Die Herstellung und planmasige Anwendung chemi scher Pflanzenschutzmittel geht etwa bis in die Mitte des vorigen Jahrhunderts zuruck, als verschiedene Krankheiten und Schadlinge den Weinbau gefahrdeten und diese mit Kupfersalzen, Schwefel-, Arsen-Praparaten, Tabakbruhen and a. bekampft wurden. Neben Kulturmasnahmen, Zuchtung resistenter Nutzpflanzen und pflanzen-hygienischen Masnahmen sind fur den Pflanzenschutz besonders biologische Methoden empfohlen worden, weil durch sie keine Chemikalien auf das Erntegut gelangen.

Fremde Stoffe Schädlingsbekämpfungsmittel-Rückstände in Lebensmitteln

oro-pbenzoquinone (spergon), respectively, grew inthepresenceofhighconcentrations ofthefungicides andconverted themtoproducts nottoxic tothesensitive rhizobia. Theresults ofchemical assaysdemonstrated thatthepesticides were destroyed bytheresistant bacteria butnotbythesusceptible parent rhizobia. Resting cells ofthiram-metabolizing R. meliloti formedlarge quantities of dimethyldithiocarbamate, dimethylamine, andCS2fromthepesticide. The products werecharacterized bygasandthin-layer chromatography, colorimetric reactions, andultraviolet spectrometry. Dimethylamine andCS2were formed spontaneously fromdimethyldithiocarbamate, buttheyield was higher inthe presenceofR.meliloti. Thephygon-resistant bacterium converted thefungicide tofive metabolites andthereby rendered thechemical nontoxic toatestfungus. Theresistant strain ofR.phaseoli generated atleast one organic product and released about one-third ofthechlorine during itsdetoxication ofspergon. Seedtreatment withfungicides isanimportantmeansofminimizing orpreventing the harmdonebypathogenic fungi thatattack seeds ortheroots ofseedlings. These antimicrobialagents arenotspecific forthepathogens, however, andtheyinhibit fungi, bacteria, and othergroups ofmicroorganisms. Suchinhibitions areparticularly serious whenthepesticides areapplied toseeds oflegumes, because theconsequent suppression ofspecies ofRhizobiummayresult innodulation failures orreductions inthequantities ofN2fixed bythe legume-Rhizobium symbiosis. Thepresent report ispartofastudy designed toobtain strains ofroot-nodule bacteria that canbeapplied directly tofungicide-treated seeds. Theapproach involves theuseofacclimatedormutantstrains resistant tolevels of thecompounds thatareemployed inpractice. Theinvestigations presented heredealwiththe metabolism ofthepesticides andmechanisms ofresistance; a separate report willprovide dataontheinoculation, successful establishment,andN2-fixing activity ofthesenew strains onchemically treated seeds. Themetabolism ofthefungicide thiram (tetramethylthiuram disulfide) hasbeenthesubject ofsomeinquiry, andithasbeenreported to betransformed byEnteromorpha linza(11), several fungi (15), andsamples ofsoil (16).

Report on Tetramethylthiuram Disulfide

Citations

Resistance of Rhizobium strains to phygon, spergon, and thiram.

Fremde Stoffe Schädlingsbekämpfungsmittel-Rückstände in Lebensmitteln

Resistance ofRhizobium Strains toPhygon, Spergon, and Thiram

Related Papers (5)

Vulcanization with Tetramethylthiuram Disulfide.

The Crystal Structure of Tetramethylthiuram Disulphide.

Continuous process for the production of tetramethylthiuram disulphide

Phthalimidopropionylaminoethyl disulfide and preparation

Production of disulfide