Impact of some environmental factors on growth and ochratoxin A production by Aspergillus niger and Aspergillus welwitschiae

Ochratoxin A (OTA) is a nephrotoxic mycotoxin which may contaminate various foods and feed products worldwide. Aspergillus niger is one of the species responsible for OTA contamination in grapes and derived products. This species has recently been split into A. niger and Aspergillus welwitschiae. Bo...

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Bibliographic Details
Published in:International journal of food microbiology 2019-02, Vol.291, p.10-16
Main Authors: Abarca, M.L., Bragulat, M.R., Castellá, G., Cabañes, F.J.
Format: Article
Language:English
Subjects:
Absorbance
Aspergillus
Aspergillus niger
Aspergillus welwitschiae
Contamination
Culture media
Ecophysiology
Environmental factors
Environmental impact
Food contamination
Grapes
Laboratory equipment
Ochratoxin A
Raisins
Species
Sucrose
Sugar
Temperature
Water activity
Yeast
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Summary:Ochratoxin A (OTA) is a nephrotoxic mycotoxin which may contaminate various foods and feed products worldwide. Aspergillus niger is one of the species responsible for OTA contamination in grapes and derived products. This species has recently been split into A. niger and Aspergillus welwitschiae. Both species can not be distinguished by phenotypic or extrolite profiles and to date there is no ecophysiological information of A. welwitschiae. The aim of this study was to determine the effects of water activity (aw) (0.90; 0.95 and 0.98–0.99), culture media (Yeast Extract Sucrose Broth (YESB); Synthetic Grape Juice Medium (SGM); White grape juice (WGJ)) and temperature (15 °C, 25 °C and 35 °C) on the growth and OTA production of four strains of A. niger and six strains of A. welwitschiae. The assay was performed in microtiter plates, determining the absorbance at 530 nm and the concentration of OTA at 1, 2, 4 and 10 days. No significant differences were observed in absorbance and OTA values between the two species under study. The highest absorbance values were recorded in YESB, followed by SGM and WGJ. Absorbance values increased with increasing aw and temperature. The highest OTA values were obtained at 0.98–0.99 aw and the best culture media for OTA production was YESB, followed by WGJ and SGM. The studied strains of A. niger produced the highest mean OTA level at 25 °C whereas A. welwitschiae strains produced the highest mean OTA concentration at 15 °C, although not differing significantly from concentration produced at 25 °C. To our knowledge, this is the first report on the impact of some environmental factors on growth and OTA production by A. welwitschiae. •First report on the impact of some environmental factors on growth and OTA production by A. welwitschiae•No significant differences were observed in growth and OTA values between A. niger and A. welwitschiae•Optimum temperature for OTA production was 25°C for A. niger strains and 15-25°C for A. welwitschiae strains
ISSN:0168-1605
1879-3460
DOI:10.1016/j.ijfoodmicro.2018.11.001