Impact of Water Activity and Temperature on Growth and Ochratoxin A Production of Two Aspergillus carbonarius Isolates from Wine Grapes in Greece

2007 ◽  
Vol 70 (12) ◽  
pp. 2884-2888 ◽  
Author(s):  
CHRYSOULA C. TASSOU ◽  
PANTELIS I. NATSKOULIS ◽  
EFSTATHIOS Z. PANAGOU ◽  
APOSTOLOS E. SPIROPOULOS ◽  
NARESH MAGAN
Keyword(s):  
Ochratoxin A ◽  
Water Activity ◽  
Color Change ◽  
Fungal Growth ◽  
Grape Juice ◽  
Lag Phase ◽  
Aspergillus Carbonarius ◽  
Wine Grapes ◽  
Wine Production

The aim of this study was to determine the effects of water activity (aw; 0.85 to 0.98) and temperature (10 to 40°C) on the radial growth rate and ochratoxin A (OA) production of two Aspergillus carbonarius isolates in vitro. The isolates were obtained from wine grapes cultivated in Greece, and the trial was conducted with a synthetic grape juice medium similar in composition to grapes between veraison (beginning of color change) and ripeness. Fungal growth and OA production data were collected for 55 days. Response surface curves and cardinal values for aw and temperature were obtained using multiple regression analysis. The lag phase lasted from less than 1 to 10 days. Both isolates grew optimally at 30 to 35°C and 0.96 aw, but maximum OA production occurred under suboptimal growth conditions (15 to 20°C and 0.93 to 0.96 aw). Growth also was observed at 0.85 aw and 25°C, however at this same aw the fungus failed to produce mycelium at any other temperatures tested. The isolates produced OA at 15 to 30°C and 0.90 to 0.98 aw. Maximum OA production was detected after 25 days of incubation at 20°C and 0.96 aw and was 3.14 and 2.67 μgg−1, respectively, for the two strains. The isolated strains used in this study were more xerotolerant than others from the Mediterranean basin. These data will allow producers to identify and thus monitor critical environmental conditions effectively in wine grapes. These data also increase the knowledge base concerning the ability of A. carbonarius to grow and produce toxin under different ecological conditions and can contribute to the development of secondary models for the prediction and risk assessment of OA in wine production.

Aspergillus carbonarius growth and ochratoxin A production on irradiated dried grapes under different water activity and temperature conditions

2010 ◽  
Vol 3 (2) ◽  
pp. 175-182 ◽  
Author(s):  
A. Astoreca ◽  
C. Barberis ◽  
C. Magnoli ◽  
A. Dalcero
Keyword(s):  
Ochratoxin A ◽  
Water Activity ◽  
Lag Phase ◽  
Human Consumption ◽  
Aspergillus Carbonarius ◽  
Phase Growth ◽  
Wine Grapes ◽  
Wine Production ◽  
Dried Grapes ◽  
Temperature Ranges

Grapes have different destinations. The most important in the national and international market is wine production, but another is dehydration to produce raisins. Dried vine fruits are at greater risk of ochratoxin A (OTA) contamination than wine grapes because the ratio of Aspergillus carbonarius to Aspergillus niger aggregate increases during drying. The growth of these species, and consequently OTA production, can be influenced by different environmental factors, the two most important being water activity (aW) and temperature. The objective of the present work was to evaluate the lag phase, growth rate and OTA production by two A. carbonarius isolates on irradiated dried grapes at different aW (0.910, 0.928, 0.955, 0.973 and 0.995), temperatures (15, 25 and 30 °C) and incubation times (7, 14 and 21 days). Growth was observed at all aW and temperature ranges assayed. No significant differences between the growth rates reached at 25 °C and 30 °C by both isolates were observed. At the assayed conditions, OTA production occurred over the whole range of temperatures (15-30 °C), with the maximum at 25 and 30 °C depending on the aW. In general, OTA concentration increased as aW increased with no statistically significant differences at the tested incubation times. This work provides information that can be used by companies for the purpose of preventing A. carbonarius and OTA contamination during storage on this and other substrates (e.g. dried prunes, figs and apricots) destined for human consumption.

Effect of Fungicides on Growth and Ochratoxin A Production by Aspergillus carbonarius from Brazilian Wine Grapes

2016 ◽  
Vol 79 (9) ◽  
pp. 1508-1516 ◽  
Author(s):  
MICHELLE F. TERRA ◽  
NATHASHA de A. LIRA ◽  
FABIANA R. F. PASSAMANI ◽  
WILDER DOUGLAS SANTIAGO ◽  
MARIA das GRAÇAS CARDOSO ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Fungal Growth ◽  
Aspergillus Carbonarius ◽  
Low Doses ◽  
Effective Strategy ◽  
Wine Grapes ◽  
Chemical Fungicides ◽  
Better Than ◽  
Main Factor

ABSTRACT Prevention in the field of mycotoxin-producing fungi is the most effective strategy for controlling the presence of mycotoxins in foods. Chemical fungicides are widely used to protect crops, so their implications on mycotoxin production need to be considered. Therefore, the aim of this study was to evaluate the effect in vitro and on grapes of five fungicides commonly used on grape cultures in Brazil on Aspergillus carbonarius growth and ochratoxin A (OTA) production. At the doses recommended by manufacturers, most fungicides significantly reduced A. carbonarius growth and OTA production in vitro, whereas this effect was influenced by the type of fungicide, dose, and temperature. Temperature was the main factor that influenced the effectiveness of fungicides. In general, at 15°C, fungicides showed the greatest reduction on fungal growth and OTA production. Fungicide effect on grapes was different to that on a semisynthetic grape medium. All fungicide doses were not effective at controlling A. carbonarius in grapes. Thus, the direct effect of fungicides on grapes must be studied to obtain a better approximation of field conditions. The results indicate that the use of fungicides at the doses recommended by manufacturers is better than the application at low doses. This study showed that at the lowest doses, where fungal growth is not inhibited, fungicides positively stimulate OTA production.

Effect of Water Activity, Temperature, and Mixed Fungal Spore Interactions on Ochratoxin A Production by Aspergillus carbonarius

2015 ◽  
Vol 78 (2) ◽  
pp. 376-382 ◽  
Author(s):  
EFSTATHIA A. KOGKAKI ◽  
PANTELIS I. NATSKOULIS ◽  
GEORGE-JOHN E. NYCHAS ◽  
EFSTATHIOS Z. PANAGOU
Keyword(s):  
Ochratoxin A ◽  
Water Activity ◽  
Incubation Time ◽  
Interspecific Interactions ◽  
Grape Juice ◽  
Fungal Spore ◽  
Fungal Species ◽  
Aspergillus Carbonarius ◽  
Different Temperatures

The purpose of this work was to investigate the potential of two nontoxigenic Aspergillus section Nigri species (Aspergillus tubingensis and Aspergillus japonicus) to influence the in vitro ochratoxin A (OTA) production of three toxigenic Aspergillus carbonarius isolates (Ac-28, Ac-29, and Ac-33) from Greek vineyards of different geographical areas. OTA accumulation was evaluated by inoculation of 0:100, 25:75, 50:50, 75:25, and 100:0 ratios of mixed spore suspensions on a synthetic grape juice medium for up to 28 days at different temperatures (15, 20, and 25°C), water activity (aw) levels (0.95 and 0.98 aw) and incubation time (7, 14, 21, and 28 days). Results confirmed that environmental factors and fungal species had a significant effect on OTA production. Specifically, maximum OTA concentration for Ac-28 (3.21 μg g−1) and Ac-29 (7.69 μg g−1) was observed at 20°C/0.98 aw and for Ac-33 (9.13 μg g−1) at 15°C/0.95 aw, regardless of incubation time. Moreover, A. tubingensis had no significant influence on OTA concentration of all toxigenic isolates assayed, regardless of temperature, aw, and incubation time. On the other hand, the presence of A. japonicus slightly inhibited OTA production of Ac-29 and Ac-33, while for Ac-28, stimulation of OTA was observed in some cases. Overall, lower aw levels reduced OTA accumulation for Ac-28 and Ac-29, regardless of temperature, inoculum ratio, and time. On the contrary, for Ac-33, low aw increased OTA production, regardless of the investigated parameters. The importance of this study concerns the understanding of interspecific interactions on OTA diffusion by A. carbonarius in an attempt to find ways to prevent the presence of toxins in grapes and their derivatives.

Effect of Temperature, Water Activity, and pH on Growth and Production of Ochratoxin A by Aspergillus niger and Aspergillus carbonarius from Brazilian Grapes

2014 ◽  
Vol 77 (11) ◽  
pp. 1947-1952 ◽  
Author(s):  
FABIANA REINIS FRANCA PASSAMANI ◽  
THAIS HERNANDES ◽  
NOELLY ALVES LOPES ◽  
SABRINA CARVALHO BASTOS ◽  
WILDER DOUGLAS SANTIAGO ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Ochratoxin A ◽  
Water Activity ◽  
Fungal Growth ◽  
Grape Juice ◽  
Effect Of Temperature ◽  
Aspergillus Carbonarius ◽  
Optimal Conditions ◽  
Wide Range ◽  
Temperature Water

The growth of ochratoxigenic fungus and the presence of ochratoxin A (OTA) in grapes and their derivatives can be caused by a wide range of physical, chemical, and biological factors. The determination of interactions between these factors and fungal species from different climatic regions is important in designing models for minimizing the risk of OTA in wine and grape juice. This study evaluated the influence of temperature, water activity (aw), and pH on the development and production of OTA in a semisynthetic grape culture medium by Aspergillus carbonarius and Aspergillus niger strains. To analyze the growth conditions and production of OTA, an experimental design was conducted using response surface methodology as a tool to assess the effects of these abiotic variables on fungal behavior. A. carbonarius showed the highest growth at temperatures from 20 to 33°C, aw between 0.95 and 0.98, and pH levels between 5 and 6.5. Similarly, for A. niger, temperatures between 24 and 37°C, aw greater than 0.95, and pH levels between 4 and 6.5 were optimal. The greatest toxin concentrations for A. carbonarius and A. niger (10 μg/g and 7.0 μg/g, respectively) were found at 15°C, aw 0.99, and pH 5.35. The lowest pH was found to contribute to greater OTA production. These results show that the evaluated fungi are able to grow and produce OTA in a wide range of temperature, aw, and pH. However, the optimal conditions for toxin production are generally different from those optimal for fungal growth. The knowledge of optimal conditions for fungal growth and production of OTA, and of the stages of cultivation in which these conditions are optimal, allows a more precise assessment of the potential risk to health from consumption of products derived from grapes.

Effect of five fungicides on growth and ochratoxin A production by two Aspergillus carbonarius and Aspergillus niger isolated from Moroccan grapes

2014 ◽  
Vol 4 (3) ◽  
pp. 118-126
Author(s):  
Souad Zouhair ◽  
Souad Qjidaa Qjidaa ◽  
Atar Selouane ◽  
Driss Bouya ◽  
Cony Decock ◽  
...  
Keyword(s):  
Growth Rate ◽  
Ochratoxin A ◽  
Fungal Growth ◽  
Inhibitory Effect ◽  
Aspergillus Carbonarius ◽  
Total Inhibition ◽  
Germination And Growth ◽  
Dose Dependent Increase ◽  
Dose Dependent

Five fungicides azoxystrobin (ortiva), benomyl (benlate), hexaconazole (hexa), pyrimethanil (scala) and thiabendazole (tectocal) were tested sepa-rately in vitro for their ability to inhibit the growth of two ochratoxigenic strains of A. niger and A. carbonarius previously isolated from grapes. All fungicides effectively reduced the growth rate of A. carbonarius and A. niger from 34 to 100% at the recommended dose (RD). Thiabendazole caused total inhibition of spore germination and growth of the two strains, regardless of the doses assayed. Benomyl completely inhibited growth of A. niger whereas for A. carbonarius, concentrations above 0.02xRD were required to prevent the growth. The inhibitory effect of hexaconazole, azoxystrobin and pyrime-thanil was dose-dependent. At sub-lethal concentrations of three fungicides, a dose-dependent increase in in ochratoxin A biosynthesis by two strains was observed. The use of fungicide should be checked for its ability to inhibit fungal growth as well as for their effect in terms of mycotoxins biosynthesis.

scholarly journals Host Factors Modulating Ochratoxin A Biosynthesis during Fruit Colonization by Aspergillus carbonarius

2020 ◽  
Vol 7 (1) ◽  
pp. 10
Author(s):  
Uriel Maor ◽  
Omer Barda ◽  
Sudharsan Sadhasivam ◽  
Yang Bi ◽  
Varda Zakin ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Sugar Content ◽  
Grape Juice ◽  
Growth Conditions ◽  
Host Factors ◽  
Fungal Colonization ◽  
Toxic Metabolite ◽  
Aspergillus Carbonarius ◽  
The Impact

Aspergillus carbonarius is a strong and consistent ochratoxin A (OTA) producer and considered to be the main source of this toxic metabolite in grapes and grape products such as wine, grape juice and dried vine fruit. OTA is produced under certain growth conditions and its accumulation is affected by several environmental factors, such as growth phase, substrate, temperature, water activity and pH. In this study, we examined the impact of fruit host factors on regulation and accumulation of OTA in colonized grape berries, and assessed in vitro the impact of those factors on the transcriptional levels of the key genes and global regulators contributing to fungal colonization and mycotoxin synthesis. We found that limited sugar content, low pH levels and high malic acid concentrations activated OTA biosynthesis by A. carbonarius, both in synthetic media and during fruit colonization, through modulation of global regulator of secondary metabolism, laeA and OTA gene cluster expression. These findings indicate that fruit host factors may have a significant impact on the capability of A. carbonarius to produce and accumulate OTA in grapes.

Effect of water activity and temperature on growth of Aspergillus carbonarius and Aspergillus tubingensis and their interactions on ochratoxin A production

2015 ◽  
Vol 8 (1) ◽  
pp. 99-105 ◽  
Author(s):  
M.L. Chiotta ◽  
D.M. Sosa ◽  
M.L. Ponsone ◽  
S.N. Chulze
Keyword(s):  
Ochratoxin A ◽  
Water Activity ◽  
Grape Juice ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Aspergillus Carbonarius ◽  
Aspergillus Tubingensis ◽  
Defence Reaction ◽  
Aspergillus Section

Aspergillus section Nigri are described as the main source of ochratoxin A (OTA) contamination in grapes and wine worldwide. The grape-growing area in Argentina has a wide latitudinal extension with ecological variations that allow the classification of well-demarcated regions. The aims of this study were: to determine the effect of eco-physiological parameters on growth of Aspergillus tubingensis and Aspergillus carbonarius and to evaluate the interaction between these species on OTA production in synthetic grape juice medium under different water activity (aw) and temperature conditions. The results showed that optimal growth conditions for A. tubingensis and A. carbonarius were 0.980 aw and 28 °C, however A. tubingensis grew faster than A. carbonarius at all temperatures and aw tested. OTA production by A. carbonarius was favoured at 20 °C and 0.950-0.965 aw, during 14 days of incubation. The effect of A. tubingensis on OTA production by A. carbonarius was mainly dependent on temperature. At 35 °C, A. tubingensis reduced the OTA production while this effect was not observed at 20 °C. More OTA could be produced as a defence reaction against fungal competitors to maintain niche colonisation, but in this study no effects by a related species were observed.

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