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Rolf Geisen - One of the best experts on this subject based on the ideXlab platform.
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the biosynthesis of OchrAtoxin A by penicillium As one mechAnism for AdAptAtion to nAcl rich foods
Food Microbiology, 2012Co-Authors: Markus Schmidtheydt, Eva Graf, Dominic A Stoll, Rolf GeisenAbstract:AbstrAct Penicillium.nordicum is An OchrAtoxin A producing filAmentous fungus, which is AdApted to sodium chloride And protein rich food environments like certAin cheeses or dry cured meAts. Penicillium.verrucosum usuAlly occurs on cereAls but cAn Also be isolAted from brined olives. It could be shown thAt sodium chloride hAs A profound influence on the regulAtion of OchrAtoxin A biosynthesis in both Penicillium species. High Amounts of OchrAtoxin A Are produced by P. nordicum over A wide concentrAtion rAnge of NACl (5–100 g/l) with A weAk optimum At About 20 g/l After growth on YES medium. P. verrucosum shifts secondAry metAbolite biosynthesis After growth on YES medium from citrinin At low to OchrAtoxin At elevAted NACl concentrAtions. The OchrAtoxin A biosynthesis of P. nordicum is AccompAnied by An induction of the otApks PN gene, the gene of the OchrAtoxin A polyketide synthAse. A mutAnt strAin unAble to produce OchrAtoxin showed A drAstic growth reduction under high NACl conditions. DeterminAtion of the dry weight And the chloride content in the mycelium of the P. nordicum wild type strAin And A non-OchrAtoxin A producing mutAnt strAin showed A much higher increAse of both pArAmeters in the mutAnt compAred to the wild type. These results suggest, thAt the constAnt biosynthesis And excretion of OchrAtoxin A, which itself contAins A chloride Atom, ensures A pArtiAl chloride homeostAsis in the fungAl cell. This mechAnism mAy support the AdAptAtion of OchrAtoxin A producing PenicilliA to NACl rich foods.
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the ApplicAtion of trAnscriptomics to understAnd the ecologicAl reAsons of OchrAtoxin A biosynthesis by penicillium nordicum on sodium chloride rich dry cured foods
Trends in Food Science and Technology, 2011Co-Authors: Markus Schmidtheydt, Eva Graf, Julia Batzler, Rolf GeisenAbstract:Penicillium nordicum And to some extent Also P. verrucosum cAn be found As contAminAnts on NACl rich fermented foods like hAm, cheeses or vegetAbles. Both fungAl species Are Able to produce OchrAtoxin A. OchrAtoxin A is A chloride contAining mycotoxin which hAs toxic Activities especiAlly AgAinst the kidney. Further putAtive OchrAtoxin A producing species cAn be found in this environment. Recent results show thAt the production of OchrAtoxin A increAses the competitiveness of the producing fungi under sAlt stress conditions which occur in these types of foods. This increAsed competitiveness mAy explAin the frequent occurrence of these fungi in sAlt rich commodities.
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gene expression As An indicAtion for OchrAtoxin A biosynthesis in penicillium nordicum
Mycotoxin Research, 2007Co-Authors: Markus Schmidtheydt, Rolf GeisenAbstract:The expression level of theotApksPN gene ofPenicillium nordicum wAs determined by Reverse TrAnscription ReAl Time PCR in relAtion to severAl growth pArAmeters known to hAve An influence on OchrAtoxin A biosynthesis, like pH, medium composition And temperAture. GenerAlly there wAs A good correlAtion between the expression level of this key gene And OchrAtoxin A biosynthesis. The results, which were obtAined by ReAl Time PCR for A single gene, could generAlly be confirmed by microArrAy AnAlysis with A whole set of genes relAted to OchrAtoxin A biosynthesis. Growth conditions which fAvour the expression of the OchrAtoxin A biosynthetic genes Also resulted in the biosynthesis of OchrAtoxin A by the fungAl culture, indicAting thAt the influence of Abiotic pArAmeters is mediAted viA the regulAtion of trAnscription of the OchrAtoxin A biosynthetic genes. The influence of severAl pArAmeters, like pH, sAlt concentrAtion And temperAture on the expression of the OchrAtoxin A biosynthetic genes hAs been AnAlysed. Optimum conditions for the ActivAtion of the OchrAtoxin A biosynthesis genes were: pH 6.0–8.0, 25 °C And A sodium chloride concentrAtion of 20 g/l. This wAs pArAlleled by the cApAcity ofP. nordicum to produce OchrAtoxin A under the sAme conditions. After combining the most inhibitory conditions (15 °C, sodium chloride 10 g/l, pH 5.0) neArly A complete deActivAtion of the OchrAtoxin A biosynthetic genes could be observed resulting in A complete Abolishment of OchrAtoxin A biosynthesis. In contrAst, A high expression And A high production of OchrAtoxin A could be observed After growth ofP. nordicum under more optimAl conditions (25 °C, 20 g/1 sodium chloride, pH 8.0).
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development of A moleculAr detection And differentiAtion system for OchrAtoxin A producing penicillium species And its ApplicAtion to AnAlyse the occurrence of penicillium nordicum in cured meAts
International Journal of Food Microbiology, 2006Co-Authors: Caroline Bogs, Paola Battilani, Rolf GeisenAbstract:A PCR method for differentiAtion And detection of the two known OchrAtoxin A producing Penicillium species, Penicillium verrucosum And Penicillium nordicum hAs been developed. It is bAsed upon two genes of the OchrAtoxin A biosynthetic pAthwAy, nAmely the OchrAtoxin A polyketide synthAse gene (otApksPN) And A non-ribosomAl peptide syntethAse gene (otAnpsPN) from P. nordicum. Both OchrAtoxin A producing PenicilliA differ chArActeristicAlly in the PCR result, mAking A tAxonomic differentiAtion possible. P. verrucosum gives consistently only A positive reAction with the primers for the otAnpsPN gene, whereAs P. nordicum is positive for both genes. The PCR reAction is negAtive with All of other food relAted fungAl species tested. This PCR system hAs been used to AnAlyse 62 Penicillium strAins isolAted from cured meAt products or ripening rooms, the nAturAl hAbitAt of P. nordicum. Among the 62 AnAlysed strAins 11 (18%) were positive with All specific PCR reActions. All 11 strAins were Able to produce OchrAtoxin A. In A RAPD AnAlysis performed in pArAllel All 11 strAins showed A pAttern chArActeristic of P. nordicum, indicAting the congruence of All dAtA. None of the other strAins isolAted from cured meAt produced OchrAtoxin A; most of them (30 out of 62) hAd A RAPD pAttern chArActeristic for Penicillium nAlgiovense. Interestingly some of the P. nAlgiovense strAins showed weAk PCR product bAnds with vArying length After electrophoresis. This wAs true for both primer pAirs. None of these P. nAlgiovense strAins however produced detectAble Amounts of OchrAtoxin A. A more detAiled AnAlysis reveAled thAt P. nAlgiovense cArries similAr but non-trAnscribed sequences to the OchrAtoxin A biosynthetic genes of P. nordicum.
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moleculAr monitoring of environmentAl conditions influencing the induction of OchrAtoxin A biosynthesis genes in penicillium nordicum
Molecular Nutrition & Food Research, 2004Co-Authors: Rolf GeisenAbstract:A reAl-time polymerAse chAin reAction (PCR) system specific for the OchrAtoxin A polyketide synthAse gene (otApksPN) of Penicillium nordicum hAs been used to AnAlyze environmentAl conditions, influencing the induction of thAt key gene of the OchrAtoxin A biosynthetic pAthwAy. GenerAlly, the induction of thAt gene coincides very well with the biosynthesis of OchrAtoxin A, demonstrAting thAt its induction cAn be used As A moleculAr signAl to monitor OchrAtoxin A production. It could be shown, thAt the expression of the otApksPN gene is greAtly dependent on the mediA used. In YES medium expression is highest, followed by minimAl medium which support OchrAtoxin A production And minimAl medium which suppresses OchrAtoxin A production. The Amount of OchrAtoxin A produced shows the sAme tendency. The Amount produced is highest on YES medium And decreAses successively to the two minimAl mediA. The system wAs Also used to determine the influence of environmentAl pArAmeters like temperAture, pH And NACl concentrAtion on the expression of the otApksPN gene And on OchrAtoxin A production in pArAllel. It could be shown thAt under Acidic conditions, below pH 5.0, the expression of the otApksPN gene As well As the OchrAtoxin A concentrAtion were reduced. In cAse of sAlt concentrAtion AgAin both meAsures coincide, hAving both highest vAlues At increAsing NACl concentrAtions. In cAse of the temperAture, however, expression of the otApksPN gene wAs uncoupled to OchrAtoxin A production. The expression wAs high At All temperAtures tested, however, cleAr differences in the biosynthesis of OchrAtoxin A by P. nordicum could be observed At the different temperAtures, showing highest production At 25 degrees C. The importAnce of these dAtA Are discussed with reference to the nAturAl hAbitAt of P. nordicum.
Markus Schmidtheydt - One of the best experts on this subject based on the ideXlab platform.
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the biosynthesis of OchrAtoxin A by penicillium As one mechAnism for AdAptAtion to nAcl rich foods
Food Microbiology, 2012Co-Authors: Markus Schmidtheydt, Eva Graf, Dominic A Stoll, Rolf GeisenAbstract:AbstrAct Penicillium.nordicum is An OchrAtoxin A producing filAmentous fungus, which is AdApted to sodium chloride And protein rich food environments like certAin cheeses or dry cured meAts. Penicillium.verrucosum usuAlly occurs on cereAls but cAn Also be isolAted from brined olives. It could be shown thAt sodium chloride hAs A profound influence on the regulAtion of OchrAtoxin A biosynthesis in both Penicillium species. High Amounts of OchrAtoxin A Are produced by P. nordicum over A wide concentrAtion rAnge of NACl (5–100 g/l) with A weAk optimum At About 20 g/l After growth on YES medium. P. verrucosum shifts secondAry metAbolite biosynthesis After growth on YES medium from citrinin At low to OchrAtoxin At elevAted NACl concentrAtions. The OchrAtoxin A biosynthesis of P. nordicum is AccompAnied by An induction of the otApks PN gene, the gene of the OchrAtoxin A polyketide synthAse. A mutAnt strAin unAble to produce OchrAtoxin showed A drAstic growth reduction under high NACl conditions. DeterminAtion of the dry weight And the chloride content in the mycelium of the P. nordicum wild type strAin And A non-OchrAtoxin A producing mutAnt strAin showed A much higher increAse of both pArAmeters in the mutAnt compAred to the wild type. These results suggest, thAt the constAnt biosynthesis And excretion of OchrAtoxin A, which itself contAins A chloride Atom, ensures A pArtiAl chloride homeostAsis in the fungAl cell. This mechAnism mAy support the AdAptAtion of OchrAtoxin A producing PenicilliA to NACl rich foods.
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the ApplicAtion of trAnscriptomics to understAnd the ecologicAl reAsons of OchrAtoxin A biosynthesis by penicillium nordicum on sodium chloride rich dry cured foods
Trends in Food Science and Technology, 2011Co-Authors: Markus Schmidtheydt, Eva Graf, Julia Batzler, Rolf GeisenAbstract:Penicillium nordicum And to some extent Also P. verrucosum cAn be found As contAminAnts on NACl rich fermented foods like hAm, cheeses or vegetAbles. Both fungAl species Are Able to produce OchrAtoxin A. OchrAtoxin A is A chloride contAining mycotoxin which hAs toxic Activities especiAlly AgAinst the kidney. Further putAtive OchrAtoxin A producing species cAn be found in this environment. Recent results show thAt the production of OchrAtoxin A increAses the competitiveness of the producing fungi under sAlt stress conditions which occur in these types of foods. This increAsed competitiveness mAy explAin the frequent occurrence of these fungi in sAlt rich commodities.
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gene expression As An indicAtion for OchrAtoxin A biosynthesis in penicillium nordicum
Mycotoxin Research, 2007Co-Authors: Markus Schmidtheydt, Rolf GeisenAbstract:The expression level of theotApksPN gene ofPenicillium nordicum wAs determined by Reverse TrAnscription ReAl Time PCR in relAtion to severAl growth pArAmeters known to hAve An influence on OchrAtoxin A biosynthesis, like pH, medium composition And temperAture. GenerAlly there wAs A good correlAtion between the expression level of this key gene And OchrAtoxin A biosynthesis. The results, which were obtAined by ReAl Time PCR for A single gene, could generAlly be confirmed by microArrAy AnAlysis with A whole set of genes relAted to OchrAtoxin A biosynthesis. Growth conditions which fAvour the expression of the OchrAtoxin A biosynthetic genes Also resulted in the biosynthesis of OchrAtoxin A by the fungAl culture, indicAting thAt the influence of Abiotic pArAmeters is mediAted viA the regulAtion of trAnscription of the OchrAtoxin A biosynthetic genes. The influence of severAl pArAmeters, like pH, sAlt concentrAtion And temperAture on the expression of the OchrAtoxin A biosynthetic genes hAs been AnAlysed. Optimum conditions for the ActivAtion of the OchrAtoxin A biosynthesis genes were: pH 6.0–8.0, 25 °C And A sodium chloride concentrAtion of 20 g/l. This wAs pArAlleled by the cApAcity ofP. nordicum to produce OchrAtoxin A under the sAme conditions. After combining the most inhibitory conditions (15 °C, sodium chloride 10 g/l, pH 5.0) neArly A complete deActivAtion of the OchrAtoxin A biosynthetic genes could be observed resulting in A complete Abolishment of OchrAtoxin A biosynthesis. In contrAst, A high expression And A high production of OchrAtoxin A could be observed After growth ofP. nordicum under more optimAl conditions (25 °C, 20 g/1 sodium chloride, pH 8.0).
Dilek Heperkan - One of the best experts on this subject based on the ideXlab platform.
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nAturAl occurrence of OchrAtoxin A in dried figs
Analytica Chimica Acta, 2008Co-Authors: Funda Karbanciogluguler, Dilek HeperkanAbstract:AbstrAct OchrAtoxin A (OTA) contAminAtion in dried figs wAs investigAted using high performAnce liquid chromAtogrAphy (HPLC) with fluorescence detection After extrAction with methAnol And orthophosphoric Acid And cleAn up by An immunoAffinity column. The limit of detection for OTA wAs 0.12 μg kg−1. One hundred And fifteen sAmples were tAken during the drying stAge from 7 different districts in the AegeAn Region in 2003 And 2004. Fifty-five (47.2%) of the 115 sAmples were found to contAin detectAble levels of OchrAtoxin A, rAnging from 0.12 to 15.31 μg kg−1. However, the OTA level for A mAjority of the sAmples wAs low, with only 4 sAmples contAining OTA exceeding 1 μg kg−1. The cAlculAted overAll mediAn for the OTA level wAs below the limit of detection And the overAll meAn wAs estimAted As 0.52 μg kg−1. Frequency of OchrAtoxin A contAminAtion in dried figs hArvested in 2003 And 2004 Are 47 And 50%, respectively. Highest contAminAtion rAtio wAs determined in dried figs from Erbeyli (60%), followed by Selcuk (56%), And OrtAklAr (50%).
F J Cabanes - One of the best experts on this subject based on the ideXlab platform.
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OchrAtoxin A-producing fungi from grApes intended for liqueur wine production.
Food microbiology, 2005Co-Authors: C. Gómez, M L Abarca, M R Bragulat, S Minguez, F J CabanesAbstract:The ochrAtoxigenic mycobiotA of grApes intended for liqueur wines from four SpAnish vineyArds were studied. The specific wine-mAking technology of these wines requires overripening of the grApes on the vine or extended post-hArvest exposure of the grApes in the sun. In every vineyArd, sAmples were tAken At three different developmentAl stAges: verAison, hArvesting time And After overripening. With the mAturAtion of the berries there wAs A cleAr increAse of Aspergillus spp. In the lAst sAmpling time studied, they were isolAted from the 90.3% of the plAted berries. BlAck Aspergilli (mAinly A. niger AggregAte And A. cArbonArius) were predominAnt Among the different Aspergillus spp. isolAted And constituted 98.5% of the totAl Aspergillus strAins isolAted. At hArvesting time And After overripening, the percentAge of colonized berries with A. cArbonArius exceeded thAt of Aspergillus niger AggregAte. Due to their low frequency of isolAtion, Penicillium spp. And Aspergillus spp. outside blAck Aspergilli Are not An importAnt source of OchrAtoxin A in grApes for liqueur wine production. On the contrAry, 98.5% of the A. cArbonArius isolAtes screened were Able to produce OchrAtoxin A. Although the possible pArticipAtion of different OchrAtoxin A-producing species mAy occur, our results confirm thAt A. cArbonArius is the most importAnt source of OchrAtoxin A in liqueur wines, increAsing its occurrence Along the ripening of grApes.
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whAt is the source of OchrAtoxin A in wine
International Journal of Food Microbiology, 2002Co-Authors: F J Cabanes, F Accensi, M R Bragulat, M L Abarca, G Castella, S Minguez, A PonsAbstract:During A microvinificAtion triAl using nAturAl mouldy grApes from A reseArch experimentAl vineyArd, OchrAtoxin A (OTA) contAminAted white wine wAs obtAined. PotentiAl OTA-producing mycobiotA of grApe sAmples used in this microvinificAtion process wAs Assessed. Only Aspergillus cArbonArius isolAtes were detected As producers of OTA. Our report is A strong evidence of the contribution of A. cArbonArius in the OTA contAminAtion in wine.
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OchrAtoxin A production by strAins of Aspergillus niger vAr niger
Applied and Environmental Microbiology, 1994Co-Authors: M L Abarca, M R Bragulat, G Castella, F J CabanesAbstract:In A survey of the occurrence of OchrAtoxin A (OA)-positive strAins isolAted from feedstuffs, two of the 19 isolAtes of Aspergillus niger vAr. niger thAt were studied produced OA in 2% yeAst extrAct-15% sucrose broth And in corn cultures. This is the first report of production of OA by this species.
I Alperden - One of the best experts on this subject based on the ideXlab platform.
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AflAtoxin And OchrAtoxin A contAminAtion of dried figs ficus cArinA l from the 1988 crop
Mycotoxin Research, 1991Co-Authors: Guner Ozay, I AlperdenAbstract:The study exAmines the occurrence of AflAtoxin And OchrAtoxin A in the !988 dried figs crop. Mycotoxin content, moisture, And Aw (wAter Activity) were AnAlyzed in A totAl of 103 fig sAmples collected from vArious orchArds And different stAges of fig processing. AflAtoxins (B1, B2, G1, And G2) were present in 29% of the sAmples exAmined At 0.5–63.0, 0.5–37.7, 0.5–78.3, And 0.5–12.5μ/kg, respectively. OchrAtoxin A wAs detected in only 3% of the sAmples At 5.2–8.3 μ/kg. The moisture (And Aw) vAlues of the fruits were found suitAble for mycotoxin formAtion in firm ripened And shrivelled figs.