Penicillium purpurogenum

The expression of the acetyl xylan esterase II (axeII) gene from Penicillium purpurogenum is repressed by glucose and induced by xylan, as well as to a small degree by xylose and xylitol. This gene is expressed at neutral pH, but not under alkaline or acidic conditions, in agreement with previous findings for other xylanolytic genes of this organism. This is the first report showing pH regulation of an axe gene.

The aim of this study was to isolate fungi able to produce pigments. Fifty strains were isolated from the Amazon soil by the conventional technique of serial dilution. Submerged fermentation was performed in Czapeck broth in order to select strains able to synthesise pigments. Five strains were able to produce pigments and were identified by sequencing the rDNA (ITS regions). These fungi were identified as Penicillium sclerotiorum 2AV2, Penicillium sclerotiorum 2AV6, Aspergillus calidoustus 4BV13, Penicillium citrinum 2AV18 and Penicillium purpurogenum 2BV41. P. sclerotiorum 2AV2 produced intensely coloured pigments and were therefore selected for chemical characterisation. NMR identified the pigment as sclerotiorin. In this work, the influence of nutrients on sclerotiorin yield was also studied and it was verified that rhamnose and peptone increased production when used separately. These results indicate that Amazonian fungi bioprospecting is a viable means to search for new sources of natural dyes.

The expression of the acetyl xylan esterase II (axeII) gene from Penicillium purpurogenum is repressed by glucose and induced by xylan, as well as to a small degree by xylose and xylitol. This gene is expressed at neutral pH, but not under alkaline or acidic conditions, in agreement with previous findings for other xylanolytic genes of this organism. This is the first report showing pH regulation of an axe gene.

The expression of the acetyl xylan esterase II (axeII) gene from Penicillium purpurogenum is repressed by glucose and induced by xylan, as well as to a small degree by xylose and xylitol. This gene is expressed at neutral pH, but not under alkaline or acidic conditions, in agreement with previous findings for other xylanolytic genes of this organism. This is the first report showing pH regulation of an axe gene.

Eects of temperature (25, 30 and 36 C) and propionic acid concentration (129, 258 and 516 ppm) on the growth of Aspergillus parasiticus in solid media were analyzed. Growth rate, expressed as the increment of colony diameter per unit of time, was studied as a function of storage time employing the Arrhenius model. The inverse of the lag phase was ®tted to an Arrhenius-type equation and the inhibition index was also calculated. A linear relationship between the lag phase and the reciprocal growth rate at dierent propionic acid concentrations was assessed by linear regression analysis. Fungi behavior was modeled considering the main controlling factors and a response surface methodology was established in terms of propionic acid and temperature. The proposed model could be used in food microbiology to predict the growth of toxicogenic fungi growth.

The effect of eight organic acids (propionic, acetic, formic, lactic, tartaric, citric, oxalic and malic acids) as antifungal agents on the growth of four fungi (Aspergillus flavus, Penicillium purpurogenum, Rhizopus nigricans and Fusarium oxysporum) were studied. The high acidity appeared for oxalic acid being 0.14 at the high concentration (10%), while the lowest acidity recorded for propionic acid and acetic acid being 2.71 and 2.56 at the low concentration (5%). It was observed that, there was no relationship between the efficacy of organic acid and its final pH. Acetic acid (10%) has the highest inhibitory effect on A. flavus being 45.21%, but tartaric acid (5%) and citric acid (5%) gave the same lowest inhibition effect (0.42%). The lowest value of mycelium dry weight (MDW) of P. purpurogenum was 5.92 g/l when acetic acid was used (10%), but the highest value was 9.38 g/l when tartaric acid (5%) was used. Formic acid (10%) had a strong effect on the inhibition growth of R. nig...

The effect of eight organic acids (propionic, acetic, formic, lactic, tartaric, citric, oxalic and malic acids) as antifungal agents on the growth of four fungi (Aspergillus flavus, Penicillium purpurogenum, Rhizopus nigricans and Fusarium oxysporum) were studied. The high acidity appeared for oxalic acid being 0.14 at the high concentration (10%), while the lowest acidity recorded for propionic acid and acetic acid being 2.71 and 2.56 at the low concentration (5%). It was observed that, there was no relationship between the efficacy of organic acid and its final pH. Acetic acid (10%) has the highest inhibitory effect on A. flavus being 45.21%, but tartaric acid (5%) and citric acid (5%) gave the same lowest inhibition effect (0.42%). The lowest value of mycelium dry weight (MDW) of P. purpurogenum was 5.92 g/l when acetic acid was used (10%), but the highest value was 9.38 g/l when tartaric acid (5%) was used. Formic acid (10%) had a strong effect on the inhibition growth of R. nig...

The effect of eight organic acids (propionic, acetic, formic, lactic, tartaric, citric, oxalic and malic acids)
as antifungal agents on the growth of four fungi (Aspergillus flavus, Penicillium purpurogenum, Rhizopus
nigricans and Fusarium oxysporum) were studied. The high acidity appeared for oxalic acid being 0.14 at
the high concentration (10%), while the lowest acidity recorded for propionic acid and acetic acid being
2.71 and 2.56 at the low concentration (5%). It was observed that, there was no relationship between the
efficacy of organic acid and its final pH. Acetic acid (10%) has the highest inhibitory effect on A. flavus
being 45.21%, but tartaric acid (5%) and citric acid (5%) gave the same lowest inhibition effect (0.42%).
The lowest value of mycelium dry weight (MDW) of P. purpurogenum was 5.92 g/l when acetic acid was
used (10%), but the highest value was 9.38 g/l when tartaric acid (5%) was used. Formic acid (10%) had a
strong effect on the inhibition growth of R. nigricans being 28.65%, similar to propionic acid (10%), acetic
acid (10%), lactic acid (10%), tartaric acid (10%) and citric acid (10%) being 26.57%, 26.38%, 26.19%,
23.53% and 24.48%, respectively. But malic acid (5%) and oxalic acid (5%) were having a week effect on
R. nigricans being 5.31% and 6.45%, respectively. Lactic acid (10%) has the highest inhibitory effect on F.
oxysporum being 34.45% and the lowest value was in the case of tartaric acid (5%) being 1.68%. Four
treatments were used to determine aflatoxin B1 production. The highest inhibition (50%) was observed by
R. nigricans in the presence of formic acid (10%). Acetic acid in 10% level inhibited the toxic secretion of
A. flavus and P. purpurogenum to become 25% and 40%, respectively. Lactic acid (10%) gave 35%
inhibition of toxin production in the presence of F. oxysporum.

Montréal. Il a pour mission la promotion et la valorisation de la recherche. Érudit offre des services d'édition numérique de documents scientifiques depuis 1998. Pour communiquer avec les responsables d'Érudit : erudit@umontreal.ca Article Mélanie R. Mecteau, Joseph Arul et Russell J. Tweddell Phytoprotection, vol. 89, n° 1, 2008, p. 1-6. Pour citer la version numérique de cet article, utiliser l'adresse suivante : http://id.erudit.org/iderudit/000377ar Note : les règles d'écriture des références bibliographiques peuvent varier selon les différents domaines du savoir. Ce document est protégé par la loi sur le droit d'auteur. L'utilisation des services d'Érudit (y compris la reproduction) est assujettie à sa politique d'utilisation que vous pouvez consulter à l'URI http://www.erudit.org/documentation/eruditPolitiqueUtilisation.pdf Document téléchargé le 15 September 2009 "Effect of different salts on the development of Fusarium solani var. coeruleum, a causal agent of potato dry rot" PHYTOPROTECTION 89 : 1-6 1Ṫ

Montréal. Il a pour mission la promotion et la valorisation de la recherche. Érudit offre des services d'édition numérique de documents scientifiques depuis 1998. Pour communiquer avec les responsables d'Érudit : erudit@umontreal.ca Article Mélanie R. Mecteau, Joseph Arul et Russell J. Tweddell Phytoprotection, vol. 89, n° 1, 2008, p. 1-6. Pour citer la version numérique de cet article, utiliser l'adresse suivante : http://id.erudit.org/iderudit/000377ar Note : les règles d'écriture des références bibliographiques peuvent varier selon les différents domaines du savoir. Ce document est protégé par la loi sur le droit d'auteur. L'utilisation des services d'Érudit (y compris la reproduction) est assujettie à sa politique d'utilisation que vous pouvez consulter à l'URI http://www.erudit.org/documentation/eruditPolitiqueUtilisation.pdf Document téléchargé le 15 September 2009 "Effect of different salts on the development of Fusarium solani var. coeruleum, a causal agent of potato dry rot" PHYTOPROTECTION 89 : 1-6 1Ṫ

Potato dry rot, caused by Fusarium sambucinum, is a major postharvest disease of economic significance worldwide. Postharvest application of thiabendazole to control dry rot is becoming less effective since many strains of F. sambucinum have become resistant to this fungicide. Thus, alternative control strategies are needed. In vitro studies showed that several salts (02 ) inhibited completely mycelial growth and spore germination of F. sambucinum. Among these salts, sodium benzoate, sodium metabisulfite, potassium sorbate, trisodium phosphate and aluminium salts were fungitoxic. In vivo studies showed that aluminium chloride in curative application and sodium metabisulfite, sodium carbonate and sodium bicarbonate in preventive application significantly reduced the development of dry rot in potato tuber. Results from this study demonstrate that selected salts can be used to control potato dry rot.