scholarly journals Predictive Modeling and Validation on Growth, Production of Asexual Spores and Ochratoxin A of Aspergillus Ochraceus Group under Abiotic Climatic Variables

2021 ◽  
Vol 9 (6) ◽  
pp. 1321
Author(s):  
Ahmed Abdel-Hadi ◽  
Bader Alshehri ◽  
Mohammed Waly ◽  
Mohammed Aboamer ◽  
Saeed Banawas ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Polynomial Regression ◽  
Fungal Growth ◽  
Climatic Variables ◽  
Aspergillus Ochraceus ◽  
Activity Levels ◽  
Third Order ◽  
The Third ◽  
Group A ◽  
Growth Production

This study aimed to generate predictive models for growth, sporulation, and ochratoxin A (OTA) production under abiotic climatic variables, including temperatures (15–35 °C) and water activity levels (0.99–0.90 aw) by Aspergillus ochraceus group. The data were divided into three sets: one for training, one for testing, and the third one for model validation. Optimum growth occurred at 0.95 aw and 25 °C and 0.95 aw and 30 °C for A. westerdijkiae and A. steynii, respectively. Significantly improved A. westerdijkiae and A. steynii spore production occurred at 0.95 aw and 20 °C and 0.90 aw and 35 °C, respectively. A. steynii and A. westerdijkiae produced the majority of OTA at 35 °C and 0.95 aw and 25–30 °C at 0.95–0.99 aw, respectively. The accuracy of the third-order polynomial regression model reached 96% in growth cases, 94.7% in sporulation cases, and 90.9% in OTA production cases; the regression coefficients (R2) ranged from 0.8819 to 0.9978 for the Aspergillus ochraceus group. A reliable agreement was reached between the predicted and observed growth, sporulation, and OTA production. The effects of abiotic climatic variables on growth, sporulation, and OTA production of A. ochraceus group have been effectively defined, and the models generated were responsible for adequately predicted and validated models against data from other strains within A. ochraceus group that had been published in the literature under the current treatments. These models could be successfully implemented to predict fungal growth and OTA contamination on food matrices for these strains under these conditions.

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.

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.

The influence of the regression model and final speed criteria on the reliability of lactate threshold determined by the Dmax method in endurance-trained runners

2016 ◽  
Vol 41 (10) ◽  
pp. 1039-1044 ◽  
Author(s):  
Júlio César Camargo Alves ◽  
Cecília Segabinazi Peserico ◽  
Geraldo Angelo Nogueira ◽  
Fabiana Andrade Machado
Keyword(s):  
Regression Model ◽  
Regression Models ◽  
Lactate Threshold ◽  
Polynomial Regression ◽  
Third Order ◽  
The Third ◽  
Constant Regression ◽  
Order Polynomial ◽  
Final Speed ◽  
Polynomial Regression Model

Few studies verified the reliability of the lactate threshold determined by Dmax method (LTDmax) in runners and it remains unclear the effect of the regression model and the final speed on the reliability of LTDmax. This study aimed to examine the test–retest reliability of the speed at LTDmax in runners, considering the effects of the regression models (exponential-plus-constant vs third-order polynomial) and final speed criteria (complete vs proportional). Seventeen male, recreational runners performed 2 identical incremental exercise tests, with increments of 1 km·h–1 each for 3 min on treadmill to determine peak treadmill speed (Vpeak) and lactate threshold. Earlobe capillary blood samples were collected during rest between the stages. The Vpeak was defined as the speed of the last complete stage (complete final speed criterion) and as the speed of the last complete stage added to the fraction of the incomplete stage (proportional final speed criterion). Lactate threshold was determined from exponential-plus-constant and from third-order polynomial regression models with both complete and proportional final speed criteria and from fixed blood lactate level of 3.5 mmol·L−1 (LT3.5mM). The LTDmax obtained from the exponential-plus-constant regression model presented higher reliability (coefficient of variation (CV) ≤ 3.7%) than the LTDmax calculated from the third-order polynomial regression model (CV ≤ 5.8%) and LT3.5mM (CV = 5.4%). The proportional final speed criterion is more appropriate when using the exponential-plus-constant regression model, but less appropriate when using the third-order polynomial regression model. In conclusion, exponential-plus-constant using the proportional final speed criterion is preferred over LT3.5mM and over third-order polynomial regression model to determine a reliable LTDmax.

scholarly journals Desempenho de cultivares de mamona no Semiárido paraibano: componentes de crescimento e teor de óleo

2015 ◽  
Vol 10 (5) ◽  
pp. 127
Author(s):  
R. R. A. Lacerda ◽  
A. S. Souza ◽  
G. F. Frutado ◽  
I. S. Queiroga ◽  
W. A. Lacerda
Keyword(s):  
Experimental Design ◽  
Castor Bean ◽  
Oil Content ◽  
Precision Farming ◽  
The Other ◽  
Raw Material ◽  
Production Yield ◽  
Third Order ◽  
The Third ◽  
Growth Production

<p>A cultura da mamona vem despontando como uma das principais matérias-primas, para produção de óleo, especialmente no Nordeste, todavia muitos fatores têm dificultado o estabelecimento dessa lavoura em novas áreas dentre os quais destacam-se a falta de cultivares adaptadas a cada região de cultivo. O presente estudo foi desenvolvido com o objetivo de identificar cultivares de mamona com adaptação ao sertão paraibano. O trabalho foi conduzido no Sítio Monte Alegre zona rural do município de Pombal - PB, o delineamento experimental foi em blocos ao acaso com sete tratamentos compostos pelos cultivares BRS Nordestina; BRS Paraguaçu; BRS Energia; AL Guarany-2002; IAC 2028; IAC Guarany e IAC 80, com quatro repetições, foram avaliadas as características de crescimento e teor de óleo nas sementes. Dos resultados registrou-se maior valor de comprimento do racemo as cultivares IAC 80 e IAC 2028, considerando as médias dos racemos até a 3ª ordem, para as características de massa e número de frutos por racemos foi constatado que a IAC 80 superou estatisticamente as demais cultivares, o maior teor de óleo nas sementes foi observado na cultivar BRS Energia que também conferiu maior rendimento de óleo entre as sete cultivares. Apesar disso, acredita-se que novos estudos devem ser realizados em diferentes épocas e formas de manejo para se identificar com maior precisão qual cultivar melhor se adapta a região.</p><p><strong><em>Performance cultivars castor bean cultivars in Semiarid Paraiba: components of growth and oil content</em></strong></p><p><strong>Abstract</strong><strong>: </strong>Currently the culture of castor has emerged as a of the main raw material for the production of oil, especially in the Northeast, however many factors has hampered the establishment of this tilth in new areas among which is the lack of cultivars adapted to each region of cultivation. This study was developed with the objective of identify castor’s cultivars with adaptation to the Paraíba Sertão. The study was conducted on Sítio Monte Alegre countryside of municipality of Pombal - PB, the experimental design was the of random blocks with seven treatments composed by BRS Northeastern; Paraguaçu BRS; BRS Energy; Guarany AL-2002, IAC 2028, IAC Guarany and IAC 80, with four replications were evaluated characteristics of growth, production, yield and oil content in the seeds. From the results was registrated a higher From the results recorded was greater value of the length of cluster IAC 80 and IAC cultivars in 2028, considering the averages of racemes up to the third order, the characteristics of mass and number of fruits per raceme was found that 80 IAC statistically outperformed the other cultivars, the higher oil content in seeds was observed in BRS Energy also gave higher oil yield among the seven cultivars. Nevertheless, we believe that further studies should be performedat different times and forms of management to identify with greater precision farming which best fits the region.<strong></strong></p>

scholarly journals Effect of Cinnamaldehyde on Morphological Alterations of Aspergillus ochraceus and Expression of Key Genes Involved in Ochratoxin A Biosynthesis

Toxins ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 340 ◽  
Author(s):  
Limin Wang ◽  
Jing Jin ◽  
Xiao Liu ◽  
Yan Wang ◽  
Yang Liu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Ochratoxin A ◽  
Fungal Growth ◽  
Regulatory Genes ◽  
Aspergillus Ochraceus ◽  
Transcriptional Level ◽  
Enzymatic Reactions ◽  
Morphological Alterations ◽  
Natural Agents ◽  
Intracellular Organelles

Ochratoxin A (OTA) is a potent nephrotoxic, hepatotoxic, and teratogenic compound which is a significant mycotoxin contaminates cereals during storage. Aspergillus ochraceus is the most common producer of OTA in cereals and cereal-derived products. Cinnamaldehyde is a natural substance derived from plant cinnamon playing an important role in the reduction of OTA contamination. In this study, the antifungal and antitoxigenic effect of cinnamaldehyde was investigated with its mechanisms of inhibition of fungal growth at the morphological and ultrastructural levels, and inhibition of OTA biosynthesis at the transcriptional level. Significant A. ochraceus growth was inhibited at 0.4–1.6 mmol/L with fumigation. A. ochraceus exposed to 0.4 mmol/L of cinnamaldehyde indicated irreversible harmful morphological and ultrastructural modifications such as the folding of the cell, the loss of integrity of the cell wall, the disruption of plasma membrane, the destruction of the mitochondria, and the absence of intracellular organelles. These alterations may be attributed to its inhibition of enzymatic reactions that regulate cell wall synthesis, thus disturbing the morphogenesis and growth of A. ochraceus. In the presence of cinnamaldehyde, the tested biosynthetic and regulatory genes like pks, nrps, veA, laeA and velB were highly downregulated. Moreover, the downregulation effect of cinnamaldehyde increased proportionally with the concentrations. These results suggest that the decrease of OTA production by cinnamaldehyde is attributed to the downregulation of the transcriptional levels of OTA biosynthetic and regulatory genes besides the inhibition of fungal growth. The study reveals the mechanisms of the antifungal and antitoxigenic activities of cinnamaldehyde against A. ochraceus, and further emphasizes that cinnamaldehyde could be a safe and effective natural agents against OTA contamination during cereals storage.

scholarly journals Quantitative Proteomic Profiling of Fungal Growth, Development, and Ochratoxin A Production in Aspergillus ochraceus on High- and Low-NaCl Cultures

Toxins ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 51
Author(s):  
Yan Wang ◽  
Yue Guan ◽  
Wei Lin ◽  
Hao Yan ◽  
Jing Neng ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Growth And Development ◽  
Salt Content ◽  
Membrane Integrity ◽  
Meat Products ◽  
Fungal Growth ◽  
High Salt ◽  
Aspergillus Ochraceus ◽  
High Salt Content ◽  
Cured Meat

Dry-cured meat products are worldwide food with high-salt content, and filamentous fungi are beneficial to the maturation process. However, some salt-tolerant strains of Aspergillus and Penicillium produce ochratoxin A (OTA) on these products and thus threaten food safety. In our study, proteomic analysis was performed to reveal the mechanism of adaptability to high-salt environment by Aspergillus ochraceus. Twenty g/L and 70 g/L NaCl substrates were used to provide medium- and high-NaCl content environments, respectively. The NaCl addition could induce fungal growth, but only 20 g/L NaCl addition could induce spore production while 70 g/L repressed it. Proteomics analysis identified 2646 proteins in A. ochraceus fc-1, of which 237 and 251 were differentially expressed with 20 g/L and 70 g/L NaCl addition, respectively. Potential factors affecting fungal growth and development were identified by GO and KEGG analyses of biological process, cellular component, and molecular function terms. The results revealed that ergosterol synthesis pathway was significantly upregulated with 20 g/L and 70 g/L NaCl addition. However, fungal growth and development including OTA production were complex processes associated with many factors including nutrient uptake, cell membrane integrity, cell cycle, energy metabolism, intracellular redox homeostasis, protein synthesis and processing, autophagy, and secondary metabolism. Reactive oxygen species may be an important window to understand the mechanism that medium-salt content was conducive to intracellular signal transduction while high-salt content caused oxidative stress. The findings would help to improve the processes and storage conditions of dry-cured meat products.

scholarly journals The Influence of NaCl and Glucose Content on Growth and Ochratoxin A Production by Aspergillus ochraceus, Aspergillus carbonarius and Penicillium nordicum

Toxins ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 515
Author(s):  
Yan Wang ◽  
Hao Yan ◽  
Jing Neng ◽  
Jian Gao ◽  
Bolei Yang ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Salt Content ◽  
Meat Products ◽  
Fungal Growth ◽  
Aspergillus Ochraceus ◽  
Aspergillus Carbonarius ◽  
Mycelium Growth ◽  
Glucose Content ◽  
High Sugar ◽  
Penicillium Nordicum

Ochratoxin A (OTA) is a nephrotoxic mycotoxin, which deserves particular attention for its widespread contamination of a variety of food and feed. Aspergillus ochraceus, Aspergillus carbonarius, and Penicillium nordicum are an important source of OTA in three different kinds of food commodities, including cereals, grape and dried fruit products, and dry-cured meat products. Deeper knowledge of OTA production and mycelium growth related to the high-sugar or NaCl-rich environments was gained in this manuscript. A. ochraceus and P. nordicum were likely to have greater growth rates in medium supplied with certain concentrations of NaCl (0–80 g/L), and the colony diameter was the largest at the salt content of 40 g/L. P. nordicum was more suitable to grow in NaCl-riched medium, the OTA production was increased to 316 ppb from 77 ppb when 20 g/L NaCl was added. The capability of OTA production was inhibited when salt content was 40 g/L and 60 g/L in A. ochraceus and P. nordicum, respectively. As the glucose content increased to 250 g/L, the capacity of mycelium growth and sporulation was increased significantly in A. ochraceus and A. carbonarius. A. carbonarius was more suitable to grow in high-sugar grape products. OTA production was significantly promoted with an added 100 g/L glucose in A. carbonarius. OTA production was inhibited when glucose content was 150 g/L and in 200 g/L in A. ochraceus and A. carbonarius, respectively. NaCl and glucose have an effect on fungal growth and OTA production, and the activation of biosynthetic genes of OtaA. These results would allow designing new strategies to prevent OTA accumulation on sugar or NaCl-riched foodstuffs and achieve the objective to manufacture cereals, dried vine fruits and dry-cured ham, free of OTA.

Probe size and 5th-order aberration

1987 ◽  
Vol 45 ◽  
pp. 134-135 ◽  
Author(s):  
Zhifeng Shao
Keyword(s):  
Electron Probe ◽  
Spherical Aberration ◽  
Wave Length ◽  
Cylindrical Symmetry ◽  
Electron Wave ◽  
Third Order ◽  
The Third ◽  
Probe Radius ◽  
Small Probe ◽  
Probe Size

A small electron probe has many applications in many fields and in the case of the STEM, the probe size essentially determines the ultimate resolution. However, there are many difficulties in obtaining a very small probe.Spherical aberration is one of them and all existing probe forming systems have non-zero spherical aberration. The ultimate probe radius is given byδ = 0.43Csl/4ƛ3/4where ƛ is the electron wave length and it is apparent that δ decreases only slowly with decreasing Cs. Scherzer pointed out that the third order aberration coefficient always has the same sign regardless of the field distribution, provided only that the fields have cylindrical symmetry, are independent of time and no space charge is present. To overcome this problem, he proposed a corrector consisting of octupoles and quadrupoles.

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