scholarly journals Integrating gene expression, ecology and mycotoxin production by Fusarium and Aspergillus species in relation to interacting environmental factors

2016 ◽  
Vol 9 (5) ◽  
pp. 673-684 ◽  
Author(s):  
N. Magan ◽  
A. Medina
Keyword(s):  
Environmental Factors ◽  
Fusarium Verticillioides ◽  
Fusarium Culmorum ◽  
Toxin Production ◽  
Stress Conditions ◽  
Toxin Gene ◽  
Biosynthetic Genes ◽  
Mycotoxin Production ◽  
Extreme Stress ◽  
Temperature Conditions

Environmental factors, such as water availability (water activity, aw), temperature and their interactions, have a significant impact on the life cycle of mycotoxigenic fungi. Growth and mycotoxin production are influenced by these interacting factors resulting in a broader range of aw × temperature conditions for germination, than growth or mycotoxin production. The biosynthetic genes are mostly clustered together and by using microarrays with sub-arrays for specific mycotoxins, such as trichothecenes, fumonisins and aflatoxins it has been possible to examine the relationship between interacting aw × temperature conditions on growth, toxin gene cluster expression and relate these to phenotypic toxin production. The data for groups of biosynthetic genes (Fusarium culmorum/Fusarium graminearum; Fusarium verticillioides; Aspergillus flavus) were integrated with data on growth and mycotoxin production under different aw × temperature conditions using a mixed growth model. This was used to correlate these factors and predict toxin levels which may be produced under different abiotic stress conditions. Indeed, the relative importance of the different genes could be examined using ternary diagrams of the relative expression of 3 genes at a time in relation to aw, temperature and mycotoxin production to identify the most important relationships. The effect of three-way interacting environmental factors representative of climate change (CC) scenarios (water stress × temperature (+2-4 °C) × elevated CO2 (350-400 vs 650 and 1000 ppm) on growth and mycotoxin production by A. flavus and by species of the Aspergillus section Circumdati and section Nigri have been determined. These studies on maize grain and coffee, respectively, suggest that while growth may not be significantly affected, mycotoxin production may be stimulated by CC factors. This approach to integrate such data sets and model the relationships could be a powerful tool for predicting the relative toxin production under extreme stress conditions, including CC scenarios.

scholarly journals Integrating toxin gene expression, growth and fumonisin B 1 and B 2 production by a strain of Fusarium verticillioides under different environmental factors

2013 ◽  
Vol 10 (85) ◽  
pp. 20130320 ◽  
Author(s):  
Angel Medina ◽  
Markus Schmidt-Heydt ◽  
Diana L. Cárdenas-Chávez ◽  
Roberto Parra ◽  
Rolf Geisen ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Systems Approach ◽  
Fusarium Verticillioides ◽  
Model Fitting ◽  
Toxin Production ◽  
Product Formation ◽  
Toxin Gene ◽  
Relative Expression ◽  
Food Commodities

The objective of this study was to integrate data on the effect of water activity ( a w ; 0.995–0.93) and temperature (20–35°C) on activation of the biosynthetic FUM genes, growth and the mycotoxins fumonisin (FB 1 , FB 2 ) by Fusarium verticillioides in vitro . The relative expression of nine biosynthetic cluster genes ( FUM1 , FUM7 , FUM10 , FUM11 , FUM12 , FUM13 , FUM14 , FUM16 and FUM19 ) in relation to the environmental factors was determined using a microarray analysis. The expression was related to growth and phenotypic FB 1 and FB 2 production. These data were used to develop a mixed-growth-associated product formation model and link this to a linear combination of the expression data for the nine genes. The model was then validated by examining datasets outside the model fitting conditions used (35°C). The relationship between the key gene ( FUM1 ) and other genes in the cluster ( FUM11, FUM13, FUM9, FUM14 ) were examined in relation to a w , temperature, FB 1 and FB 2 production by developing ternary diagrams of relative expression. This model is important in developing an integrated systems approach to develop prevention strategies to control fumonisin biosynthesis in staple food commodities and could also be used to predict the potential impact that climate change factors may have on toxin production.

scholarly journals Modelling the relationship between environmental factors, transcriptional genes and deoxynivalenol mycotoxin production by strains of two Fusarium species

2010 ◽  
Vol 8 (54) ◽  
pp. 117-126 ◽  
Author(s):  
M. Schmidt-Heydt ◽  
R. Parra ◽  
R. Geisen ◽  
N. Magan
Keyword(s):  
Environmental Factors ◽  
Control Strategies ◽  
Fusarium Species ◽  
Fusarium Culmorum ◽  
Mycotoxin Production ◽  
Contour Maps ◽  
Complex Interactions ◽  
Time Changes ◽  
First Time ◽  
The Relationship

The effect of changes in temperature/water activity ( a w ) on growth, deoxynivalenol (DON) production and trichothecene gene cluster expression (18 genes) for strains of Fusarium culmorum and Fusarium graminearum was studied. The expression data for six key transcription genes ( TRI4, TRI5 , TRI6, TRI10, TRI12 and TRI13 ) were analysed using multiple regression analyses to model the relationship between these various factors for the first time. Changes in a w and temperature significantly ( p = 0.05) affected growth and DON. Microarray data on expression of these genes were significantly related to DON production for both strains. Multi-regression analysis was done and polynomial models found to best fit the relationship between actual/predicted DON production relative to the expression of these TRI genes and environmental factors. This allowed prediction of the amounts of DON produced in two-dimensional contour maps to relate expression of these genes to either a w or temperature. These results suggest complex interactions between gene expression ( TRI genes), environmental factors and mycotoxin production. This is a powerful tool for understanding the role of these genes in relation to environmental factors and enables more effective targeted control strategies to be developed.

scholarly journals Resistance of Maize Hybrids to Fusarium graminearum, F. culmorum, and F. verticillioides Ear Rots with Toothpick and Silk Channel Inoculation, as Well as Their Toxin Production

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1283 ◽  
Author(s):  
Akos Mesterhazy ◽  
Eva Toldine Toth ◽  
Sandor Szel ◽  
Monika Varga ◽  
Beata Toth
Keyword(s):  
Food Safety ◽  
Fusarium Graminearum ◽  
Fusarium Verticillioides ◽  
Genetic Regulation ◽  
Fusarium Culmorum ◽  
Decisive Role ◽  
Toxin Production ◽  
Ear Rot ◽  
Additional Food ◽  
Toxin Regulation

Testing Fusarium resistance to ear rots in maize requires a well-supported methodology and tests for toxin responses. In this study, commercial hybrids were tested for resistance to Fusarium graminearum, Fusarium culmorum, and Fusarium verticillioides (kernel and silk channel), as well as their toxin response. One third of the hybrids tested showed a similar resistance or susceptibility to the three pathogens and their toxin response, but there is no proof for their genetic background being the same or different. The performance of the remaining hybrids was highly variable and supports the idea of different genetic regulation. The mean ear rot severity of the kernel resistance was doubled compared with the silk channel resistance data. The ear rot and toxin tests displayed significant positive correlations, verifying the decisive role of resistance in toxin regulation. Several hybrids, termed toxigenic hybrids, showed significant extra toxin production, indicating an additional food safety risk. The toothpick method gave more reliable results and a better differentiation of genotypes. The resistance to different Fusarium spp. in a specific growing region should be analyzed separately in independent resistance tests. Through this, the food safety risks could be better identified. Susceptible hybrids should not be used for commercial production.

scholarly journals A systems approach to model the relationship between aflatoxin gene cluster expression, environmental factors, growth and toxin production by Aspergillus flavus

2011 ◽  
Vol 9 (69) ◽  
pp. 757-767 ◽  
Author(s):  
Ahmed Abdel-Hadi ◽  
Markus Schmidt-Heydt ◽  
Roberto Parra ◽  
Rolf Geisen ◽  
Naresh Magan
Keyword(s):  
Gene Expression ◽  
Environmental Factors ◽  
Aspergillus Flavus ◽  
Biosynthetic Pathway ◽  
Systems Approach ◽  
Toxin Production ◽  
Relative Expression ◽  
Temperature Conditions ◽  
The Impact ◽  
The Relationship

A microarray analysis was used to examine the effect of combinations of water activity ( a w , 0.995–0.90) and temperature (20–42°C) on the activation of aflatoxin biosynthetic genes (30 genes) in Aspergillus flavus grown on a conducive YES (20 g yeast extract, 150 g sucrose, 1 g MgSO 4 ·7H 2 O) medium. The relative expression of 10 key genes ( aflF , aflD , aflE , aflM , aflO , aflP , aflQ , aflX , aflR and aflS ) in the biosynthetic pathway was examined in relation to different environmental factors and phenotypic aflatoxin B 1 (AFB 1 ) production. These data, plus data on relative growth rates and AFB 1 production under different a w × temperature conditions were used to develop a mixed-growth-associated product formation model. The gene expression data were normalized and then used as a linear combination of the data for all 10 genes and combined with the physical model. This was used to relate gene expression to a w and temperature conditions to predict AFB 1 production. The relationship between the observed AFB 1 production provided a good linear regression fit to the predicted production based in the model. The model was then validated by examining datasets outside the model fitting conditions used (37°C, 40°C and different a w levels). The relationship between structural genes ( aflD , aflM ) in the biosynthetic pathway and the regulatory genes ( aflS , aflJ ) was examined in relation to a w and temperature by developing ternary diagrams of relative expression. These findings are important in developing a more integrated systems approach by combining gene expression, ecophysiological influences and growth data to predict mycotoxin production. This could help in developing a more targeted approach to develop prevention strategies to control such carcinogenic natural metabolites that are prevalent in many staple food products. The model could also be used to predict the impact of climate change on toxin production.

scholarly journals Temporal Variations in Patterns of Clostridioides difficile Strain Diversity and Antibiotic Resistance in Thailand

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 714
Author(s):  
Supapit Wongkuna ◽  
Tavan Janvilisri ◽  
Matthew Phanchana ◽  
Phurt Harnvoravongchai ◽  
Amornrat Aroonnual ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Antimicrobial Susceptibility ◽  
Reference Strain ◽  
Toxin Production ◽  
Temporal Variations ◽  
Toxin Gene ◽  
Data Sets ◽  
Clostridioides Difficile ◽  
Life Threatening ◽  
Susceptibility Profiles

Clostridioides difficile has been recognized as a life-threatening pathogen that causes enteric diseases, including antibiotic-associated diarrhea and pseudomembranous colitis. The severity of C. difficile infection (CDI) correlates with toxin production and antibiotic resistance of C. difficile. In Thailand, the data addressing ribotypes, toxigenic, and antimicrobial susceptibility profiles of this pathogen are scarce and some of these data sets are limited. In this study, two groups of C. difficile isolates in Thailand, including 50 isolates collected from 2006 to 2009 (THA group) and 26 isolates collected from 2010 to 2012 (THB group), were compared for toxin genes and ribotyping profiles. The production of toxins A and B were determined on the basis of toxin gene profiles. In addition, minimum inhibitory concentration of eight antibiotics were examined for all 76 C. difficile isolates. The isolates of the THA group were categorized into 27 A−B+CDT− (54%) and 23 A-B-CDT- (46%), while the THB isolates were classified into five toxigenic profiles, including six A+B+CDT+ (23%), two A+B+CDT− (8%), five A−B+CDT+ (19%), seven A−B+CDT− (27%), and six A−B−CDT− (23%). By visually comparing them to the references, only five ribotypes were identified among THA isolates, while 15 ribotypes were identified within THB isolates. Ribotype 017 was the most common in both groups. Interestingly, 18 unknown ribotyping patterns were identified. Among eight tcdA-positive isolates, three isolates showed significantly greater levels of toxin A than the reference strain. The levels of toxin B in 3 of 47 tcdB-positive isolates were significantly higher than that of the reference strain. Based on the antimicrobial susceptibility test, metronidazole showed potent efficiency against most isolates in both groups. However, high MIC values of cefoxitin (MICs 256 μg/mL) and chloramphenicol (MICs ≥ 64 μg/mL) were observed with most of the isolates. The other five antibiotics exhibited diverse MIC values among two groups of isolates. This work provides evidence of temporal changes in both C. difficile strains and patterns of antimicrobial resistance in Thailand.

scholarly journals Systemic Infection by Fusarium verticillioides in Maize Plants Grown Under Three Temperature Regimes

Plant Disease ◽  
2008 ◽  
Vol 92 (12) ◽  
pp. 1695-1700 ◽  
Author(s):  
A. Murillo-Williams ◽  
G. P. Munkvold
Keyword(s):  
High Temperature ◽  
Environmental Factors ◽  
Fusarium Verticillioides ◽  
Systemic Infection ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Kernel Infection ◽  
Temperature Regimes ◽  
Maize Plants ◽  
Systemic Development

Fusarium verticillioides causes seedling decay, stalk rot, ear rot, and mycotoxin contamination (primarily fumonisins) in maize. Systemic infection of maize plants by F. verticillioides can lead to kernel infection, but the frequency of this phenomenon has varied widely among experiments. Variation in the incidence of systemic infection has been attributed to environmental factors. In order to better understand the influence of environment, we investigated the effect of temperature on systemic development of F. verticillioides during vegetative and reproductive stages of plant development. Maize seeds were inoculated with a green fluorescent protein-expressing strain of F. verticillioides, and grown in growth chambers under three different temperature regimes. In the vegetative-stage and reproductive-stage experiments, plants were evaluated at tasseling (VT stage), and at physiological maturity (R6 stage), respectively. Independently of the temperature treatment, F. verticillioides was reisolated from nearly 100% of belowground plant tissues. Frequency of reisolation of the inoculated strain declined acropetally in aboveground internodes at all temperature regimes. At VT, the high-temperature treatment had the highest systemic development of F. verticillioides in aboveground tissues. At R6, incidence of systemic infection was greater at both the high- and low-temperature regimes than at the average-temperature regime. F. verticillioides was isolated from higher internodes in plants at R6, compared to stage VT. The seed-inoculated strain was recovered from kernels of mature plants, although incidence of kernel infection did not differ significantly among treatments. During the vegetative growth stages, temperature had a significant effect on systemic development of F. verticillioides in stalks. At R6, the fungus reached higher internodes in the high-temperature treatment, but temperature did not have an effect on the incidence of kernels (either symptomatic or asymptomatic) or ear peduncles infected with the inoculated strain. These results support the role of high temperatures in promoting systemic infection of maize by F. verticillioides, but plant-to-seed transmission may be limited by other environmental factors that interact with temperature during the reproductive stages.

scholarly journals FliW and CsrA Govern Flagellin (FliC) Synthesis and Play Pleiotropic Roles in Virulence and Physiology of Clostridioides difficile R20291

2021 ◽  
Vol 12 ◽  
Author(s):  
Duolong Zhu ◽  
Shaohui Wang ◽  
Xingmin Sun
Keyword(s):  
Bacterial Colonization ◽  
Toxin Production ◽  
Toxin Gene ◽  
Clostridioides Difficile ◽  
Significant Difference ◽  
Assembly Factor ◽  
Carbon Storage Regulator ◽  
Transcription Suppression ◽  
Post Transcriptional Regulation

Clostridioides difficile flagellin FliC is associated with toxin gene expression, bacterial colonization, and virulence, and is also involved in pleiotropic gene regulation during in vivo infection. However, how fliC expression is regulated in C. difficile remains unclear. In Bacillus subtilis, flagellin homeostasis and motility are coregulated by flagellar assembly factor (FliW), flagellin Hag (FliC homolog), and Carbon storage regulator A (CsrA), which is referred to as partner-switching mechanism “FliW-CsrA-Hag.” In this study, we characterized FliW and CsrA functions by deleting or overexpressing fliW, csrA, and fliW-csrA in C. difficile R20291. We showed that fliW deletion, csrA overexpression in R20291, and csrA complementation in R20291ΔWA (fliW-csrA codeletion mutant) dramatically decreased FliC production, but not fliC gene transcription. Suppression of fliC translation by csrA overexpression can be relieved mostly when fliW was coexpressed, and no significant difference in FliC production was detected when only fliW was complemented in R20291ΔWA. Further, loss of fliW led to increased biofilm formation, cell adhesion, toxin production, and pathogenicity in a mouse model of C. difficile infection (CDI), while fliW-csrA codeletion decreased toxin production and mortality in vivo. Our data suggest that CsrA negatively modulates fliC expression and FliW indirectly affects fliC expression through inhibition of CsrA post-transcriptional regulation. In light of “FliW-CsrA-Hag” switch coregulation mechanism reported in B. subtilis, our data also suggest that “FliW-CsrA-fliC/FliC” can regulate many facets of C. difficile R20291 pathogenicity. These findings further aid us in understanding the virulence regulation in C. difficile.

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