Impacts of Climate Change Interacting Abiotic Factors on Growth, <i>aflD</i> and <i>aflR</i> Gene Expression and Aflatoxin B<sub>1</sub> Production by <i>Aspergillus flavus</i> Strains In Vitro and on Pistachio Nuts
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 <i>Aspergillus flavus</i>, mainly resulting in contamination with aflatoxins (AFs), especiall...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-05-01
|
| Series: | Toxins |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2072-6651/13/6/385 |
| _version_ | 1797532347450523648 |
|---|---|
| author | Alaa Baazeem Alicia Rodriguez Angel Medina Naresh Magan |
| author_facet | Alaa Baazeem Alicia Rodriguez Angel Medina Naresh Magan |
| author_sort | Alaa Baazeem |
| collection | DOAJ |
| description | 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 <i>Aspergillus flavus</i>, mainly resulting in contamination with aflatoxins (AFs), especially aflatoxin B<sub>1</sub> (AFB<sub>1</sub>). The prevailing climate in which these crops are grown changes as temperature and atmospheric CO<sub>2</sub> 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), CO<sub>2</sub> (400 vs. 1000 ppm), and water stress (0.98–0.93 water activity, a<sub>w</sub>) on (a) growth (b) <i>aflD</i> and <i>aflR</i> biosynthetic gene expression and (c) AFB<sub>1</sub> production by two strains <i>A. flavus</i> (AB3, AB10) in vitro on milled pistachio-based media and when colonizing layers of shelled raw pistachio nuts. The <i>A. flavus</i> 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 AFB<sub>1</sub> production was significantly stimulated (<i>p</i> < 0.05), especially when exposed to 1000 ppm CO<sub>2</sub> at 0.98–0.95 a<sub>w</sub> and 35 °C, and sometimes in the 37 °C treatment group at 0.98 a<sub>w</sub>. The relative expression of the structural <i>aflD</i> gene involved in AFB<sub>1</sub> biosynthesis was decreased or only slightly increased, relative to the control conditions at elevated CO, regardless of the a<sub>w</sub> level examined. For the regulatory <i>aflR</i> gene expression, there was a significant (<i>p</i> < 0.05) increase in 1000 ppm CO<sub>2</sub> and 37 °C for both strains, especially at 0.95 a<sub>w</sub>. The in situ colonization of pistachio nuts resulted in a significant (<i>p</i> < 0.05) stimulation of AFB<sub>1</sub> production at 35 °C and 1000 ppm CO<sub>2</sub> for both strains, especially at 0.98 a<sub>w</sub>. At 37 °C, AFB<sub>1</sub> production was either decreased, in strain AB3, or remained similar, as in strain AB10, when exposed to 1000 ppm CO<sub>2</sub>. This suggests that CC factors may have a differential effect, depending on the interacting conditions of temperature, exposure to CO<sub>2</sub> and the level of water stress on AFB<sub>1</sub> production. |
| first_indexed | 2024-03-10T10:57:52Z |
| format | Article |
| id | doaj.art-b623eb1c27764733a69af21e96a5691c |
| institution | Directory Open Access Journal |
| issn | 2072-6651 |
| language | English |
| last_indexed | 2024-03-10T10:57:52Z |
| publishDate | 2021-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Toxins |
| spelling | doaj.art-b623eb1c27764733a69af21e96a5691c2023-11-21T21:44:51ZengMDPI AGToxins2072-66512021-05-0113638510.3390/toxins13060385Impacts of Climate Change Interacting Abiotic Factors on Growth, <i>aflD</i> and <i>aflR</i> Gene Expression and Aflatoxin B<sub>1</sub> Production by <i>Aspergillus flavus</i> Strains In Vitro and on Pistachio NutsAlaa Baazeem0Alicia Rodriguez1Angel Medina2Naresh Magan3Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi ArabiaDepartment of Animal Science and Food Production, University of Extramadura, Av. de Elvas, s/n, 06006 Badajoz, SpainApplied Mycology Group, Environment and AgriFood Theme, Cranfield University, Cranfield MK43 0AL, UKApplied Mycology Group, Environment and AgriFood Theme, Cranfield University, Cranfield MK43 0AL, UKPistachio 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 <i>Aspergillus flavus</i>, mainly resulting in contamination with aflatoxins (AFs), especially aflatoxin B<sub>1</sub> (AFB<sub>1</sub>). The prevailing climate in which these crops are grown changes as temperature and atmospheric CO<sub>2</sub> 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), CO<sub>2</sub> (400 vs. 1000 ppm), and water stress (0.98–0.93 water activity, a<sub>w</sub>) on (a) growth (b) <i>aflD</i> and <i>aflR</i> biosynthetic gene expression and (c) AFB<sub>1</sub> production by two strains <i>A. flavus</i> (AB3, AB10) in vitro on milled pistachio-based media and when colonizing layers of shelled raw pistachio nuts. The <i>A. flavus</i> 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 AFB<sub>1</sub> production was significantly stimulated (<i>p</i> < 0.05), especially when exposed to 1000 ppm CO<sub>2</sub> at 0.98–0.95 a<sub>w</sub> and 35 °C, and sometimes in the 37 °C treatment group at 0.98 a<sub>w</sub>. The relative expression of the structural <i>aflD</i> gene involved in AFB<sub>1</sub> biosynthesis was decreased or only slightly increased, relative to the control conditions at elevated CO, regardless of the a<sub>w</sub> level examined. For the regulatory <i>aflR</i> gene expression, there was a significant (<i>p</i> < 0.05) increase in 1000 ppm CO<sub>2</sub> and 37 °C for both strains, especially at 0.95 a<sub>w</sub>. The in situ colonization of pistachio nuts resulted in a significant (<i>p</i> < 0.05) stimulation of AFB<sub>1</sub> production at 35 °C and 1000 ppm CO<sub>2</sub> for both strains, especially at 0.98 a<sub>w</sub>. At 37 °C, AFB<sub>1</sub> production was either decreased, in strain AB3, or remained similar, as in strain AB10, when exposed to 1000 ppm CO<sub>2</sub>. This suggests that CC factors may have a differential effect, depending on the interacting conditions of temperature, exposure to CO<sub>2</sub> and the level of water stress on AFB<sub>1</sub> production.https://www.mdpi.com/2072-6651/13/6/385climate changeinteracting abiotic factors<i>aflD</i><i>aflR</i>aflatoxins<i>Aspergillus flavus</i> |
| spellingShingle | Alaa Baazeem Alicia Rodriguez Angel Medina Naresh Magan Impacts of Climate Change Interacting Abiotic Factors on Growth, <i>aflD</i> and <i>aflR</i> Gene Expression and Aflatoxin B<sub>1</sub> Production by <i>Aspergillus flavus</i> Strains In Vitro and on Pistachio Nuts Toxins climate change interacting abiotic factors <i>aflD</i> <i>aflR</i> aflatoxins <i>Aspergillus flavus</i> |
| title | Impacts of Climate Change Interacting Abiotic Factors on Growth, <i>aflD</i> and <i>aflR</i> Gene Expression and Aflatoxin B<sub>1</sub> Production by <i>Aspergillus flavus</i> Strains In Vitro and on Pistachio Nuts |
| title_full | Impacts of Climate Change Interacting Abiotic Factors on Growth, <i>aflD</i> and <i>aflR</i> Gene Expression and Aflatoxin B<sub>1</sub> Production by <i>Aspergillus flavus</i> Strains In Vitro and on Pistachio Nuts |
| title_fullStr | Impacts of Climate Change Interacting Abiotic Factors on Growth, <i>aflD</i> and <i>aflR</i> Gene Expression and Aflatoxin B<sub>1</sub> Production by <i>Aspergillus flavus</i> Strains In Vitro and on Pistachio Nuts |
| title_full_unstemmed | Impacts of Climate Change Interacting Abiotic Factors on Growth, <i>aflD</i> and <i>aflR</i> Gene Expression and Aflatoxin B<sub>1</sub> Production by <i>Aspergillus flavus</i> Strains In Vitro and on Pistachio Nuts |
| title_short | Impacts of Climate Change Interacting Abiotic Factors on Growth, <i>aflD</i> and <i>aflR</i> Gene Expression and Aflatoxin B<sub>1</sub> Production by <i>Aspergillus flavus</i> Strains In Vitro and on Pistachio Nuts |
| title_sort | impacts of climate change interacting abiotic factors on growth i afld i and i aflr i gene expression and aflatoxin b sub 1 sub production by i aspergillus flavus i strains in vitro and on pistachio nuts |
| topic | climate change interacting abiotic factors <i>aflD</i> <i>aflR</i> aflatoxins <i>Aspergillus flavus</i> |
| url | https://www.mdpi.com/2072-6651/13/6/385 |
| work_keys_str_mv | AT alaabaazeem impactsofclimatechangeinteractingabioticfactorsongrowthiafldiandiaflrigeneexpressionandaflatoxinbsub1subproductionbyiaspergillusflavusistrainsinvitroandonpistachionuts AT aliciarodriguez impactsofclimatechangeinteractingabioticfactorsongrowthiafldiandiaflrigeneexpressionandaflatoxinbsub1subproductionbyiaspergillusflavusistrainsinvitroandonpistachionuts AT angelmedina impactsofclimatechangeinteractingabioticfactorsongrowthiafldiandiaflrigeneexpressionandaflatoxinbsub1subproductionbyiaspergillusflavusistrainsinvitroandonpistachionuts AT nareshmagan impactsofclimatechangeinteractingabioticfactorsongrowthiafldiandiaflrigeneexpressionandaflatoxinbsub1subproductionbyiaspergillusflavusistrainsinvitroandonpistachionuts |