scholarly journals Interacting Abiotic Factors Affect Growth and Aflatoxin B1 Production Profiles of Aspergillus flavus Strains on Pistachio-Based Matrices and Pistachio Nuts

2021 ◽  
Vol 11 ◽  
Author(s):  
Alaa Baazeem ◽  
Esther Garcia-Cela ◽  
Angel Medina ◽  
Naresh Magan
Keyword(s):  
Aspergillus Flavus ◽  
Abiotic Factors ◽  
Contour Maps ◽  
Pooled Data ◽  
Pistachio Nuts ◽  
Mycotoxigenic Fungi ◽  
Pistachio Nut ◽  
Aflatoxin B

Pistachio nuts are an economically important commodity produced by many countries. They can be colonized by mycotoxigenic fungi, especially Aspergillus flavus, resulting in contamination with aflatoxins (AFs), especially aflatoxin B1 (AFB1), a Class 1a carcinogen. The objectives were to examine the effect of interactions between the two key abiotic factors, temperature and water activity (aw) on (a) in vitro growth and AFB1 production by four strains of A. flavus isolated from pistachio nuts, on a milled pistachio nut medium modified ionically (NaCl) and non-ionically (glycerol) in the range 20–35°C and 0.995–0.85 aw, (b) colonization of layers of raw pistachio nuts stored at different interacting temperature x aw conditions and on relative AFB1 production and (c) develop models to produce contour maps of the optimal and marginal boundary conditions for growth and AFB1 production by up to 4 strains of this species. On pistachio nut-based media, optimum growth of four strains of A. flavus was at 0.98–0.95 aw and 30–35°C. Optimum AFB1 production was at 30–35°C and 0.98 aw. No significant differences in growth was found on ionic and non-ionically modified media. Colonization of layers of raw pistachio nuts was slower and contamination with AFB1 significantly less than in in vitro studies. Contour maps based on the pooled data for up to four strains (in vitro, in situ) showed the optimum and marginal conditions for growth and AFB1 production. These data can be used to identify those conditions which represent a high, intermediate or low risk of colonization and AFB1 contamination in the pistachio nut processing chain. These results are discussed in the context of the development of appropriate intervention strategies to minimize AFB1 contamination of this economically important commodity.

scholarly journals Impacts of Climate Change Interacting Abiotic Factors on Growth, aflD and aflR Gene Expression and Aflatoxin B1 Production by Aspergillus flavus Strains In Vitro and on Pistachio Nuts

Toxins ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 385
Author(s):  
Alaa Baazeem ◽  
Alicia Rodriguez ◽  
Angel Medina ◽  
Naresh Magan
Keyword(s):  
Climate Change ◽  
Gene Expression ◽  
Water Stress ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Abiotic Factors ◽  
Pistachio Nuts ◽  
Significant Difference ◽  
Spoilage Fungi

Pistachio nuts are an important economic tree nut crop which is used directly or processed for many food-related activities. They can become colonized by mycotoxigenic spoilage fungi, especially Aspergillus flavus, mainly resulting in contamination with aflatoxins (AFs), especially aflatoxin B1 (AFB1). The prevailing climate in which these crops are grown changes as temperature and atmospheric CO2 levels increase, and episodes of extreme wet/dry cycles occur due to human industrial activity. The objectives of this study were to evaluate the effect of interacting Climate Change (CC)-related abiotic factors of temperature (35 vs. 37 °C), CO2 (400 vs. 1000 ppm), and water stress (0.98–0.93 water activity, aw) on (a) growth (b) aflD and aflR biosynthetic gene expression and (c) AFB1 production by two strains A. flavus (AB3, AB10) in vitro on milled pistachio-based media and when colonizing layers of shelled raw pistachio nuts. The A. flavus strains were resilient in terms of growth on pistachio-based media and the colonisation of pistachio nuts with no significant difference when exposed to the interacting three-way climate-related abiotic factors. However, in vitro studies showed that AFB1 production was significantly stimulated (p < 0.05), especially when exposed to 1000 ppm CO2 at 0.98–0.95 aw and 35 °C, and sometimes in the 37 °C treatment group at 0.98 aw. The relative expression of the structural aflD gene involved in AFB1 biosynthesis was decreased or only slightly increased, relative to the control conditions at elevated CO, regardless of the aw level examined. For the regulatory aflR gene expression, there was a significant (p < 0.05) increase in 1000 ppm CO2 and 37 °C for both strains, especially at 0.95 aw. The in situ colonization of pistachio nuts resulted in a significant (p < 0.05) stimulation of AFB1 production at 35 °C and 1000 ppm CO2 for both strains, especially at 0.98 aw. At 37 °C, AFB1 production was either decreased, in strain AB3, or remained similar, as in strain AB10, when exposed to 1000 ppm CO2. This suggests that CC factors may have a differential effect, depending on the interacting conditions of temperature, exposure to CO2 and the level of water stress on AFB1 production.

Abiotic factors affect growth and aflatoxin B1 production by Aspergillus flavus strains on chilli powder and red chillies

2021 ◽  
pp. 1-10
Author(s):  
D. Al-Jaza ◽  
A. Medina ◽  
N. Magan
Keyword(s):  
Aspergillus Flavus ◽  
Statistical Difference ◽  
Abiotic Factors ◽  
Significant Risk ◽  
Optimal Growth ◽  
Toxin Production ◽  
Storage Conditions ◽  
Contour Maps ◽  
Lag Phases

Chillies and chilli-based products are important spices on a global basis. The production, processing, transport and storage phases of chillies are prone to infection by Aspergillus Section Flavi and contamination with aflatoxins (AFs), especially aflatoxin B1 (AFB1) for which legislative limits exist in many countries. We have examined the effect of the interacting abiotic factors of water availability (water activity, aw; 0.995-0.850 aw) and temperature (15-37 °C) on (a) lag phases prior to growth, (b) growth, (c) AFB1 production and (d) contour maps of optimum and boundary conditions for colonisation and toxin production by three Aspergillus flavus strains on a 10% chilli-based medium. Additional studies with whole red chillies + A. flavus conidial inoculum on AFB1 contamination during storage for 10-20 days at 30 °C were also carried out. In vitro, the lag phases before growth were delayed by lower temperatures (15, 20 °C) and aw levels (0.928-0.901 aw). There was no statistical difference in growth between the three strains. Optimal growth was at 37 °C and 0.982 aw with no growth at 0.85 aw. Optimal temperature × aw conditions for AFB1 production were at 30 °C and 0.982 aw with no statistical difference in production between strains. No AFB1 was produced at 15-20 °C at 0.901 and 0.928 aw levels, respectively. In situ studies with A. flavus inoculated whole red chillies at 0.90 and 0.95 aw found that this species became the major component of the total fungal populations at 30 °C after 10-20 days storage. AFB1 contamination was above the European legislative limits (5 μg/kg) for spices at 0.90 aw after 20 days storage and at 0.95 aw after 10 and 20 days. This suggests that storage conditions of ≥0.90 aw, especially at ≥25-30 °C represents a significant risk of contamination with AFB1 at levels where rejection might occur, even after only 10-20 days storage.

scholarly journals In Vitro Activity of Balanites aegyptiaca and Tamarindus indica Fruit Extracts on Growth and Aflatoxigenicity of Aspergillus flavus and A. parasiticus

2013 ◽  
Vol 2 (4) ◽  
pp. 68 ◽  
Author(s):  
Saifeldin Ahmed El-nagerabi ◽  
Abdulkadir E. Elshafie ◽  
Mohamed R. Elamin
Keyword(s):  
Aspergillus Flavus ◽  
Fungal Growth ◽  
Aflatoxin Contamination ◽  
Tamarindus Indica ◽  
Balanites Aegyptiaca ◽  
Total Aflatoxin ◽  
Animal Products ◽  
Fruit Extracts ◽  
Aflatoxin B

<p>Aflatoxin and especially aflatoxin B<sub>1</sub> (AFB<sub>1</sub>) is a carcinogenic secondary metabolite synthesized by certain <em>Aspergillus </em>species. They contaminate natural and processed agricultural and animal products which render them unfit for consumption. The aim of this study was to evaluate the <em>in vitro</em> effects of <em>Balanites aegyptiaca</em> and <em>Tamarindus indica</em> fruit extracts on the growth and aflatoxin secretion of <em>Aspergillus flavus</em> (SQU21) and <em>A. parasiticus </em>(CBS921.7) strains. The two fruit extracts significantly (<em>P </em>&lt; 0.05) reduced aflatoxin and did not inhibit mycelial dry weights of the two <em>Aspergillus </em>strains. At different concentrations of balanites (2.5-10%), the inhibition of total aflatoxin was 49.9-84.8% for <em>A. flavus</em> (SQU21) and 32.1-84.4% for <em>A. parasiticus</em> (CBS921.7), whereas the inhibition of aflatoxin Bwas 38.2-81.4% and 32.8-80.6% for the two strains. Tamarind fruit extract (2.5-7.5%) caused 28.8-84.2% and 40.7-85.5% reductions in total aflatoxin and 37.1-83.5% and 33.9-85.9% in aflatoxin B for the two strains, respectively. None of these extracts inhibited the fungal growth or detoxified synthetic aflatoxin B<sub>1</sub>. We have concluded that these fruits contain various inhibitors to aflatoxin biosynthesis and secretion. Therefore, they can be used in combination as safe green biopreservatives to combat aflatoxin contamination of food.</p>

scholarly journals Chemically Characterized Nanoencapsulated Homalomena aromatica Schott. Essential oil as Green Preservative Against Fungal and Aflatoxin B1 Contamination of Stored Spices based on in Vitro and in Situ Efficacy and Favourable Safety Profile on Mice

2021 ◽  
Author(s):  
Shikha Tiwari ◽  
Neha Upadhyay ◽  
Bijendra Kumar Singh ◽  
Vipin Kumar Singh ◽  
Nawal Kishore Dubey
Keyword(s):  
Free Radical ◽  
Essential Oil ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
The Novel ◽  
Absorbing Materials ◽  
Favourable Safety ◽  
Favourable Safety Profile

Abstract Present study deals with the efficacy of nanoencapsulated Homalomena aromatica essential oil (HAEO) as a potent green preservative against toxigenic Aspergillus flavus strain (AF-LHP-NS 7), AFB1 and free radical mediated deterioration of stored spices. GC-MS analysis revealed linalool (68.51%) as the major component of HAEO. HAEO was encapsulated into chitosan nanomatrix (CS-HAEO-Ne) and characterized through SEM, FTIR and XRD. CS-HAEO-Ne completely inhibited A. flavus growth and AFB1 biosynthesis at 1.25 µL/mL and 1.0 µL/mL, respectively in comparison to unencapsulated HAEO (1.75 µL/mL and 1.25 µL/mL respectively). CS-HAEO-Ne exhibited superior antioxidant efficacy (IC50 (DPPH) = 4.5 µL/mL) over unencapsulated HAEO (IC50 (DPPH) = 15.9 µL/mL). Further, CS-HAEO-Ne caused significant reduction in ergosterol content in treated A. flavus and provoked leakage of cellular ions (Ca+ 2, Mg+ 2 and K+) as well as 260 nm and 280 nm absorbing materials. Depletion of methylglyoxal level in treated A. flavus cells deals with the novel antiaflatoxigenic efficacy of CS-HAEO-Ne. CS-HAEO-Ne depicted excellent in situ efficacy by inhibiting mold attack and AFB1 contamination, mineral preservation and acceptable sensorial profile. Moreover, broad safety paradigm (LD50 value = 8006.84 µL/kg) of CS-HAEO-Ne also suggest it as novel green preservative to enhance shelf life of stored spices.

scholarly journals Untangling the multi-regime molecular mechanism of verbenol-chemotype Zingiber officinale essential oil against Aspergillus flavus and aflatoxin B1

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Prem Pratap Singh ◽  
Atul Kumar Jaiswal ◽  
Akshay Kumar ◽  
Vishal Gupta ◽  
Bhanu Prakash
Keyword(s):  
Essential Oil ◽  
Aspergillus Flavus ◽  
Zingiber Officinale ◽  
Gene Products ◽  
Carcinogenic Effect ◽  
Biochemical Assays ◽  
Vitro Analysis ◽  
Aflatoxin B ◽  
In Vitro Analysis

AbstractAflatoxin B1 (AFB1), the natural polyketide produced by Aspergillus flavus, has a potent carcinogenic effect on humans as well as animals. In the present study, the antifungal and anti-aflatoxigenic B1 activity of chemically characterized Zingiber officinale essential oil (ZOEO) was investigated via in vitro analysis aided with molecular dynamics (MD) approaches. The GC–MS results revealed verbenol (52.41%) as the major component of oil. The antifungal and anti-aflatoxigenic activity of ZOEO was found to be 0.6 µl/ml and 0.5 µl/ml respectively. In-vitro analysis targeting the cell membrane, mitochondria and carbohydrate catabolism elucidated the probable antifungal mode of action. Further, docking and MD simulation results confirmed the inhibitory action of verbenol on the structural gene products (Nor-1, Omt-1, and Vbs) of aflatoxin biosynthetic machinery. Biochemical assays revealed the fungitoxic potential of the ZOEO while, computational results infers the stabilizing effects on the gene products upon verbenol binding leads to the impairment in its functionality. This is the first attempt to assess the multi-regime anti-AFB1 mechanism of verbenol chemotype-ZOEO targeting the Nor-1, Omt-1, and Vbs via computational approaches.

scholarly journals Aspergillus flavus and Aflatoxin Contamination of Leguminous Trees of the Sonoran Desert in Arizona

2001 ◽  
Vol 91 (9) ◽  
pp. 913-919 ◽  
Author(s):  
María L. Boyd ◽  
Peter J. Cotty
Keyword(s):  
Aspergillus Flavus ◽  
Sonoran Desert ◽  
Aflatoxin Production ◽  
Common Species ◽  
Aflatoxin Contamination ◽  
Leguminous Trees ◽  
Significant Growth ◽  
Tree Legumes ◽  
Aflatoxin B

Aspergillus spp. in section Flavi were frequently associated with desert tree legumes in uncultivated areas of the Sonoran Desert. Of 270 samples of debris and fruits of mesquite (Prosopis spp.), ironwood (Olneya tesota), acacia (Acacia spp.), and palo verde (Cercidium and Parkinsonia spp.), 87% were positive for A. flavus (S and L strains) and A. tamarii. A. flavus was the most common species (87%) among the 3,763 isolates examined. Mesquite pods were both the substrate from which A. flavus was recovered most frequently and the substrate from native habitats with the greatest aflatoxin content. In vitro, most desert legumes supported significant growth, reproduction, and aflatoxin production by A. flavus, with mesquite pods yielding 1 × 1010 propagules/g and 5,000 μg/kg of aflatoxin B1. Twenty percent of legume pods collected in the desert contained measurable quantities of aflatoxin, ranging from 1 to >2,500 μg/kg. Insect-damaged mesquite pods had significantly higher aflatoxin than intact pods. Legumes are apparently important reservoirs of aflatoxin-producing fungi and significant sources of aflatoxin contamination in the native Sonoran Desert habitats of Arizona.

scholarly journals Effect of Acclimatization in Elevated CO2 on Growth and Aflatoxin B1 Production by Aspergillus flavus Strains on Pistachio Nuts

2021 ◽  
Vol 10 (1) ◽  
pp. 49
Author(s):  
Alaa Baazeem ◽  
Angel Medina ◽  
Naresh Magan
Keyword(s):  
Water Activity ◽  
Elevated Co2 ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Abiotic Factors ◽  
Strain Differences ◽  
The Other ◽  
Mycotoxin Contamination ◽  
Pistachio Nuts

There is little knowledge of the effect of acclimatization of Aspergillus flavus strains to climate-related abiotic factors and the subsequent effects on growth and aflatoxin B1 (AFB1) production. In this study, two strains of A. flavus (AB3, AB10) were acclimatized for five generations in elevated CO2 (1000 ppm × 37 °C) on a milled pistachio-based medium. A comparison was made of the effects of non-acclimatized strains and those that were acclimatized when colonizing layers of pistachio nuts exposed to 35 or 37 °C, 400 or 1000 ppm CO2, and 0.93 or 0.98 water activity (aw), respectively. Acclimatization influenced the fitness in terms of the growth of one strain, while there was no significant effect on the other strain when colonizing pistachio nuts. AFB1, production was significantly stimulated after ten days colonization when comparing the non-acclimatized and the acclimatized AB3 strain. However, there was no significant increase when comparing these for strain AB10. This suggests that there may be inter-strain differences in the effects of acclimatization and this could have a differential influence on the mycotoxin contamination of such commodities.

Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

1974 ◽  
Vol 32 ◽  
pp. 320-321
Author(s):  
J. P. Revel
Keyword(s):  
Developmental Stages ◽  
Three Dimensional ◽  
Cell Movement ◽  
Cellular Interactions ◽  
Serial Sections ◽  
Cell Sheets ◽  
Freeze Etching ◽  
Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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