Effect of Moisture and Incubation Time on Ochratoxin A Production by an Isolate of Aspergillus ochraceus

1970 ◽  
Vol 53 (1) ◽  
pp. 89-91
Author(s):  
A F Schindler ◽  
Stanley Nesheim
Keyword(s):  
Statistical Analysis ◽  
Moisture Content ◽  
Ochratoxin A ◽  
Incubation Time ◽  
Maximum Yield ◽  
Water Levels ◽  
Aspergillus Ochraceus ◽  
Ambient Temperatures ◽  
Incubation Periods ◽  
Transfer Needle

Abstract Experiments were conducted to determine the culture requirements that would insure a probability of high ochratoxin production with a given isolate. Experiments at ambient temperatures (72 ± 2°F) determined the levels of the two most readily controlled variables, time and moisture content, during the growth of a high toxin-producing isolate (M298) of Aspergillus ochraceus. Tests were conducted in 2.8 L - Fernbach flasks containing 100 g shredded wheat and inoculated with spores on a transfer needle. Amounts of ochratoxin A/flask were determined by comparison against standards on TLC after chloroform extraction. Statistical analysis showed a relation between ochratoxin yield, water levels, and incubation periods. A water level of 40–70 ml/flask with an incubation period of 19-21 days at ambient temperatures should give a near to maximum yield of ochratoxin A.

scholarly journals Effects of temperature and incubation time on growth and ochratoxin A biosynthesis by Aspergillus carbonarius and Aspergillus ochraceus in grain-based media

2016 ◽  
Vol 10 (32) ◽  
pp. 1306-1314 ◽  
Author(s):  
Cristina de Souza Sirlei ◽  
Maria Pereira Vanessa ◽  
Reinis Franca Passamani Fabiana ◽  
Angelo Cirillo Marcelo ◽  
Luz da Cunha Rodrigo ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Incubation Time ◽  
Aspergillus Ochraceus ◽  
Aspergillus Carbonarius ◽  
Effects Of Temperature

Bioproduction of ochratoxin A and penicillic acid by members of the Aspergillus ochraceus group

1972 ◽  
Vol 18 (5) ◽  
pp. 631-636 ◽  
Author(s):  
Alex Ciegler
Keyword(s):  
Quantitative Analysis ◽  
Low Temperature ◽  
Ochratoxin A ◽  
Acid Synthesis ◽  
Aspergillus Ochraceus ◽  
Cereal Grains ◽  
Liquid Media ◽  
Penicillic Acid ◽  
Group A ◽  
Fluorescent Derivatives

Various strains of species belonging to the Aspergillus ochraceus group (A. ochraceus, A. sclerotiorum, A. alliaceus, A. ostianus, A. melleus, and A. sulphureus) can produce two mycotoxins, ochratoxin A and penicillic acid, on liquid media and in cereal grains. The quantity of each toxin produced is influenced by temperature; low temperature (10 and 20C) favor penicillic acid synthesis and higher (28C), ochratoxin A production. Generally penicillic acid is produced in yields about one to three magnitudes greater than ochratoxin A. A simple fluorodensitometric method for concomitant quantitative analysis of the two toxins has been developed based on conversion of penicillic acid and ochratoxin A to fluorescent derivatives by treatment with ammonia fumes.

Considerations in the preparation of laboratory samples for the analysis of ochratoxin A in wheat

2012 ◽  
Vol 5 (2) ◽  
pp. 107-116 ◽  
Author(s):  
S.A. Tittlemier ◽  
M. Roscoe ◽  
C. Kobialka ◽  
R. Blagden
Keyword(s):  
Ochratoxin A ◽  
Whole Grain ◽  
Laboratory Sample ◽  
Test Portion ◽  
Homogeneous Sample ◽  
Ambient Temperatures ◽  
Accuracy And Precision ◽  
Relative Standard ◽  
The Mean ◽  
Ground Wheat

A process used to prepare the test portion of ground wheat from the whole grain laboratory sample for ochratoxin A (OTA) analysis using dry comminution with homogenisation and sub-sampling via a rotary sample divider was developed and evaluated. With respect to OTA content, the developed process produced a homogeneous sample of ground wheat from 10 kg of whole grain. Relative standard deviations of the mean OTA concentration for five naturally contaminated wheat samples processed using the developed method ranged from 9% to 19% over a relevant concentration range of 1.7 to 7.6 mg/kg. Additional studies demonstrated that OTA was stable in ground wheat with moisture content between 12 to 13% for at least a year when stored at ambient temperatures. Further examination of the developed comminution and dividing procedure demonstrated that higher concentrations were measured in smaller sized particles, indicating that the accuracy and precision of OTA analyses could be affected by the particle size of ground wheat.

Genetic relationships among Brazilian strains of Aspergillus ochraceus based on RAPD and ITS sequences

2004 ◽  
Vol 50 (11) ◽  
pp. 985-988 ◽  
Author(s):  
Maria Helena Pelegrinelli Fungaro ◽  
Marciane Magnani ◽  
Laurival Antônio Vilas-Boas ◽  
Patrícia Cristina Vissotto ◽  
Márcia Cristina Furlaneto ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Sequence Data ◽  
Genetic Relationships ◽  
Its Region ◽  
Aspergillus Ochraceus ◽  
Coffee Bean ◽  
Coffee Beans ◽  
Major Species ◽  
Group A ◽  
Group B

Ochratoxin A (OA) is a mycotoxin that has been found in coffee beans and coffee beverages. Its toxicological profile includes carcinogenicity, nephrotoxicity, and immunotoxicity. Aspergillus ochraceus is the major species responsible for OA production in Brazilian coffee beans. The genetic relationships among 25 A. ochraceus strains collected from Brazilian coffee-bean samples were determined based on RAPD and internal transcribed spacer (ITS) sequence data. The isolates were resolved into 2 distinct groups, one with 4 strains (group A) and the other with 21 strains (group B). Specific nucleotide variations characterizing group A and B were found for both ITS1 and ITS2 regions. Group B is a new group proposed here to accommodate the majority of the Brazilian isolates. Each group was found to contain both toxigenic and nontoxigenic strains, indicating that there is no association between molecular genotypes and the ability to produce OA.Key words: Aspergillus ochraceus, ochratoxin A, ITS region (ITS1–5.8S–ITS2), RAPD.

scholarly journals Aflatoxigenic contamination of freshly harvested white maize (Zea mays L.) from some selected Ugandan districts

2019 ◽  
Author(s):  
Timothy Omara
Keyword(s):  
Zea Mays ◽  
Moisture Content ◽  
Ochratoxin A ◽  
Zea Mays L ◽  
Lake Victoria ◽  
Total Aflatoxin ◽  
Strategic Adaptation ◽  
Maize Varieties ◽  
Agroecological Zones

The moisture content and total aflatoxin (AF) content of 27 samples of freshly harvested white maize (Zea mays L.) from Mubende (n = 3), Ibanda (n = 3), Jinja (n = 3), Mayuge (n = 3) , Buikwe (n = 3), Hoima (n = 3), Mpigi (n = 3), Masindi (n = 3) and Bugiri (n = 3) districts of Uganda representing the agroecological zones: Lake Victoria crescent, Western Highlands, South East and Lake Albert Crescent were determined in the second season harvest of January 2019 to March 2019. Moisture content ranged from 12.9 to 18.8% (mean moisture content varied from 13.9±0.35-17.2±1.55%) with the highest moisture recorded in maize from Ibanda. The highest mean AF contamination of 11.0±3.01 μg/kg was recorded in maize from Hoima while the lowest AF content of 3.8±1.30 μg/kg was recorded in maize from Mpigi. Despite the fact that all the samples had detectable aflatoxins, none of the maize samples had aflatoxin greater than WHO regulatory limit of 20 μg/kg. White maize in Uganda are precontaminated by aflatoxins prior to harvest. Whereas the spectre of aflatoxigenic contamination of foods remains a ticklish challenge to address, strategic adaptation and deployment of appropriate interventions can help secure a safe harvest. Farmers should plant maize varieties with established maturity periods to ensure timely harvesting. Further research should assess the presence of other mycotoxins as zearalenone, sterigmatocystin, ochratoxin A, citrinin, vomitoxin and diacetoxyscirpenol that may co-occur with aflatoxins in freshly harvested maize.

scholarly journals Production of Ochratoxin A by Aspergillus ochraceus Isolated in Japan from Moldy Rice

1970 ◽  
Vol 20 (3) ◽  
pp. 452-454 ◽  
Author(s):  
Mikio Yamazaki ◽  
Yukio Maebayashi ◽  
Komei Miyaki
Keyword(s):  
Ochratoxin A ◽  
Aspergillus Ochraceus

Agrobacterium-mediated insertional mutagenesis of the ochratoxigenic fungus Aspergillus westerdijkiae

2007 ◽  
Vol 53 (1) ◽  
pp. 148-151 ◽  
Author(s):  
Marcia M Mata ◽  
Marta H Taniwaki ◽  
Beatriz T Iamanaka ◽  
Daniele Sartori ◽  
André L.M Oliveira ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Insertional Mutagenesis ◽  
Aspergillus Ochraceus ◽  
Agrobacterium Mediated Transformation ◽  
Morphological Variations ◽  
Carcinogenic Potential ◽  
Coffee Beans ◽  
Aspergillus Westerdijkiae ◽  
Polymerase Chain ◽  
First Time

Aspergillus westerdijkiae is a potent ochratoxin A (OTA) producer that has been found in coffee beans. OTA is known to have nephrotoxic effects and carcinogenic potential in animal species. Here we report for the first time the Agrobacterium-mediated transformation for Aspergillus westerdijkiae and the generation of ochratoxin-defective mutants. Conidia were transformed to hygromycin B resistance using strain AGL-1 of Agrobacterium tumefaciens. The obtained transformation frequency was up to 47 transformants per 106 target conidia. Among 600 transformants, approximately 5% showed morphological variations. Eight transformants with consistently reduced OTA production were obtained. Two of these transformants did not produce OTA (detection limit: 0.1 µg/kg); the other six mutants produced lower amounts of OTA (1%–32%) compared with the wild-type strain. By using thermal asymmetric interlaced polymerase chain reaction, we successfully identified a putative flavin adenine dinucleotide monooxygenase gene.Key words: Aspergillus ochraceus, Aspergillus westerdijkiae, Agrobacterium-mediated transformation, Agrobacterium-mediated insertional mutagenesis, ochratoxin A.

scholarly journals OPTIMIZATION AND CHARACTERIZATION OF EXO-POLYGALACTURONASE BY Aspergillus niger CULTURED VIA SOLID STATE FERMENTATION

2018 ◽  
Vol 81 (1) ◽  
Author(s):  
Halifah Pagarra ◽  
Roshanida A. Rahman ◽  
Nur Izyan Wan Azelee ◽  
Rosli Md Illias
Keyword(s):  
Solid State ◽  
Aspergillus Niger ◽  
Moisture Content ◽  
Solid State Fermentation ◽  
Incubation Time ◽  
Industrial Applications ◽  
Screening Process ◽  
Industrial Sectors ◽  
Polygalacturonase Production

Polygalacturonases represent an important member of pectinases group of enzymes with immense industrial applications. The activity of exo-polygalacturonase produced by Aspergillus niger was studied in solid state fermentation (SSF) using Nephrolepis biserrata leaves as substrate. Central composite design (CCD) was used to optimize four significant variables resulted from the screening process that has been initially analyzed for the production of exo-polygalacturonase which are incubation time, temperature, concentration of pectin and moisture content. The optimum exo-polygalacturonase production obtained was 54.64 U/g at 120 hours of incubation time, temperature at 340C, 5.0 g/L of pectin concentration and 75.26% of moisture content. For partial characterization of exo-polygalacturonase, the optimum temperature and pH were obtained at 50°C and pH 4.0, respectively. SDS-PAGE analysis showed that molecular weight of exo-polygalacturonase were 35 and 71 kDa. This study has revealed a significant production of exo-polygalacturonase by A. niger under SSF using cheap and easily available substrate and thus could found immense potential application in industrial sectors and biotechnology

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