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Furukawa T, Sakai K, Suzuki T, Tanaka T, Kushiro M, Kusumoto KI. Comparative Genome Analysis of Japanese Field-Isolated Aspergillus for Aflatoxin Productivity and Non-Productivity. J Fungi (Basel) 2024; 10:459. [PMID: 39057344 PMCID: PMC11278155 DOI: 10.3390/jof10070459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 06/21/2024] [Accepted: 06/26/2024] [Indexed: 07/28/2024] Open
Abstract
Aspergillus flavus produces aflatoxin, a carcinogenic fungal toxin that poses a threat to the agricultural and food industries. There is a concern that the distribution of aflatoxin-producing A. flavus is expanding in Japan due to climate change, and it is necessary to understand what types of strains inhabit. In this study, we sequenced the genomes of four Aspergillus strains isolated from agricultural fields in the Ibaraki prefecture of Japan and identified their genetic variants. Phylogenetic analysis based on single-nucleotide variants revealed that the two aflatoxin-producing strains were closely related to A. flavus NRRL3357, whereas the two non-producing strains were closely related to the RIB40 strain of Aspergillus oryzae, a fungus widely used in the Japanese fermentation industry. A detailed analysis of the variants in the aflatoxin biosynthetic gene cluster showed that the two aflatoxin-producing strains belonged to different morphotype lineages. RT-qPCR results indicated that the expression of aflatoxin biosynthetic genes was consistent with aflatoxin production in the two aflatoxin-producing strains, whereas the two non-producing strains expressed most of the aflatoxin biosynthetic genes, unlike common knowledge in A. oryzae, suggesting that the lack of aflatoxin production was attributed to genes outside of the aflatoxin biosynthetic gene cluster in these strains.
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Affiliation(s)
- Tomohiro Furukawa
- Institute of Food Research, National Agriculture and Food Research Organization (NARO), 2-1-12 Kannondai, Tsukuba 305-8642, Japan
| | - Kanae Sakai
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Tadahiro Suzuki
- Institute of Food Research, National Agriculture and Food Research Organization (NARO), 2-1-12 Kannondai, Tsukuba 305-8642, Japan
| | - Takumi Tanaka
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Masayo Kushiro
- Institute of Food Research, National Agriculture and Food Research Organization (NARO), 2-1-12 Kannondai, Tsukuba 305-8642, Japan
| | - Ken-Ichi Kusumoto
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
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2
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Xu J, Jiang M, Wang P, Kong Q. The Gene vepN Regulated by Global Regulatory Factor veA That Affects Aflatoxin Production, Morphological Development and Pathogenicity in Aspergillus flavus. Toxins (Basel) 2024; 16:174. [PMID: 38668599 PMCID: PMC11054512 DOI: 10.3390/toxins16040174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/02/2024] [Accepted: 03/26/2024] [Indexed: 04/29/2024] Open
Abstract
Velvet (VeA), a light-regulated protein that shuttles between the cytoplasm and the nucleus, serves as a key global regulator of secondary metabolism in various Aspergillus species and plays a pivotal role in controlling multiple developmental processes. The gene vepN was chosen for further investigation through CHIP-seq analysis due to significant alterations in its interaction with VeA under varying conditions. This gene (AFLA_006970) contains a Septin-type guanine nucleotide-binding (G) domain, which has not been previously reported in Aspergillus flavus (A. flavus). The functional role of vepN in A. flavus was elucidated through the creation of a gene knockout mutant and a gene overexpression strain using a well-established dual-crossover recombinational technique. A comparison between the wild type (WT) and the ΔvepN mutant revealed distinct differences in morphology, reproductive capacity, colonization efficiency, and aflatoxin production. The mutant displayed reduced growth rate; dispersion of conidial heads; impaired cell wall integrity; and decreased sclerotia formation, colonization capacity, and aflatoxin levels. Notably, ΔvepN exhibited complete growth inhibition under specific stress conditions, highlighting the essential role of vepN in A. flavus. This study provides evidence that vepN positively influences aflatoxin production, morphological development, and pathogenicity in A. flavus.
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Affiliation(s)
- Jia Xu
- School of Food Science and Engineering, Ocean University of China, Qingdao 266404, China; (J.X.); (M.J.)
| | - Mengqi Jiang
- School of Food Science and Engineering, Ocean University of China, Qingdao 266404, China; (J.X.); (M.J.)
| | - Peng Wang
- College of Marine Life Science, Ocean University of China, Qingdao 266003, China;
| | - Qing Kong
- School of Food Science and Engineering, Ocean University of China, Qingdao 266404, China; (J.X.); (M.J.)
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3
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Luo X, Sun K, Li HR, Zhang XY, Pan YT, Luo DL, Wu YB, Jiang HJ, Wu XH, Ma CY, Dai CC, Zhang W. Depletion of protective microbiota promotes the incidence of fruit disease. THE ISME JOURNAL 2024; 18:wrae071. [PMID: 38691444 DOI: 10.1093/ismejo/wrae071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/11/2024] [Accepted: 04/24/2024] [Indexed: 05/03/2024]
Abstract
Plant-associated microbiomes play important roles in plant health and productivity. However, despite fruits being directly linked to plant productivity, little is known about the microbiomes of fruits and their potential association with fruit health. Here, by integrating 16S rRNA gene, ITS high-throughput sequencing data, and microbiological culturable approaches, we reported that roots and fruits (pods) of peanut, a typical plant that bears fruits underground, recruit different bacterial and fungal communities independently of cropping conditions and that the incidence of pod disease under monocropping conditions is attributed to the depletion of Bacillus genus and enrichment of Aspergillus genus in geocarposphere. On this basis, we constructed a synthetic community (SynCom) consisting of three Bacillus strains from geocarposphere soil under rotation conditions with high culturable abundance. Comparative transcriptome, microbiome profiling, and plant phytohormone signaling analysis reveal that the SynCom exhibited more effective Aspergillus growth inhibition and pod disease control than individual strain, which was underpinned by a combination of molecular mechanisms related to fungal cell proliferation interference, mycotoxins biosynthesis impairment, and jasmonic acid-mediated plant immunity activation. Overall, our results reveal the filter effect of plant organs on the microbiome and that depletion of key protective microbial community promotes the fruit disease incidence.
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Affiliation(s)
- Xue Luo
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Kai Sun
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Hao-Ran Li
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Xiang-Yu Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Yi-Tong Pan
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - De-Lin Luo
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Yi-Bo Wu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Hui-Jun Jiang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Xiao-Han Wu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Chen-Yu Ma
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Chuan-Chao Dai
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
| | - Wei Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Jiangsu Province, 210023, China
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4
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Corbu VM, Gheorghe-Barbu I, Dumbravă AȘ, Vrâncianu CO, Șesan TE. Current Insights in Fungal Importance-A Comprehensive Review. Microorganisms 2023; 11:1384. [PMID: 37374886 DOI: 10.3390/microorganisms11061384] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 05/20/2023] [Accepted: 05/22/2023] [Indexed: 06/29/2023] Open
Abstract
Besides plants and animals, the Fungi kingdom describes several species characterized by various forms and applications. They can be found in all habitats and play an essential role in the excellent functioning of the ecosystem, for example, as decomposers of plant material for the cycling of carbon and nutrients or as symbionts of plants. Furthermore, fungi have been used in many sectors for centuries, from producing food, beverages, and medications. Recently, they have gained significant recognition for protecting the environment, agriculture, and several industrial applications. The current article intends to review the beneficial roles of fungi used for a vast range of applications, such as the production of several enzymes and pigments, applications regarding food and pharmaceutical industries, the environment, and research domains, as well as the negative impacts of fungi (secondary metabolites production, etiological agents of diseases in plants, animals, and humans, as well as deteriogenic agents).
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Affiliation(s)
- Viorica Maria Corbu
- Genetics Department, Faculty of Biology, University of Bucharest, 060101 Bucharest, Romania
- Research Institute of the University of Bucharest-ICUB, 91-95 Spl. Independentei, 050095 Bucharest, Romania
| | - Irina Gheorghe-Barbu
- Research Institute of the University of Bucharest-ICUB, 91-95 Spl. Independentei, 050095 Bucharest, Romania
- Department of Microbiology and Immunology, Faculty of Biology, University of Bucharest, 060101 Bucharest, Romania
| | - Andreea Ștefania Dumbravă
- Department of Microbiology and Immunology, Faculty of Biology, University of Bucharest, 060101 Bucharest, Romania
| | - Corneliu Ovidiu Vrâncianu
- Research Institute of the University of Bucharest-ICUB, 91-95 Spl. Independentei, 050095 Bucharest, Romania
- Department of Microbiology and Immunology, Faculty of Biology, University of Bucharest, 060101 Bucharest, Romania
| | - Tatiana Eugenia Șesan
- Department of Microbiology and Immunology, Faculty of Biology, University of Bucharest, 060101 Bucharest, Romania
- Academy of Agricultural Sciences and Forestry, 61 Bd. Mărăşti, District 1, 011464 Bucharest, Romania
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5
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Biodegradation of Aflatoxin B1 in Maize Grains and Suppression of Its Biosynthesis-Related Genes Using Endophytic Trichoderma harzianum AYM3. J Fungi (Basel) 2023; 9:jof9020209. [PMID: 36836323 PMCID: PMC9964583 DOI: 10.3390/jof9020209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 01/27/2023] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
Aflatoxin B1 is one of the most deleterious types of mycotoxins. The application of an endophytic fungus for biodegradation or biosuppression of AFB1 production by Aspergillus flavus was investigated. About 10 endophytic fungal species, isolated from healthy maize plants, were screened for their in vitro AFs-degrading activity using coumarin medium. The highest degradation potential was recorded for Trichoderma sp. (76.8%). This endophyte was identified using the rDNA-ITS sequence as Trichoderma harzianum AYM3 and assigned an accession no. of ON203053. It caused a 65% inhibition in the growth of A. flavus AYM2 in vitro. HPLC analysis revealed that T. harzianum AYM3 had a biodegradation potential against AFB1. Co-culturing of T. harazianum AYM3 and A. flavus AYM2 on maize grains led to a significant suppression (67%) in AFB1 production. GC-MS analysis identified two AFB1-suppressing compounds, acetic acid and n-propyl acetate. Investigating effect on the transcriptional expression of five AFB1 biosynthesis-related genes in A. flavus AYM2 revealed the downregulating effects of T. harzianum AYM3 metabolites on expression of aflP and aflS genes. Using HepaRG cell line, the cytotoxicity assay indicated that T. harazianum AYM3 metabolites were safe. Based on these results, it can be concluded that T. harzianum AYM3 may be used to suppress AFB1 production in maize grains.
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6
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Loi M, Logrieco AF, Pusztahelyi T, Leiter É, Hornok L, Pócsi I. Advanced mycotoxin control and decontamination techniques in view of an increased aflatoxin risk in Europe due to climate change. Front Microbiol 2023; 13:1085891. [PMID: 36762096 PMCID: PMC9907446 DOI: 10.3389/fmicb.2022.1085891] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023] Open
Abstract
Aflatoxins are toxic secondary metabolites produced by Aspergillus spp. found in staple food and feed commodities worldwide. Aflatoxins are carcinogenic, teratogenic, and mutagenic, and pose a serious threat to the health of both humans and animals. The global economy and trade are significantly affected as well. Various models and datasets related to aflatoxins in maize have been developed and used but have not yet been linked. The prevention of crop loss due to aflatoxin contamination is complex and challenging. Hence, the set-up of advanced decontamination is crucial to cope with the challenge of climate change, growing population, unstable political scenarios, and food security problems also in European countries. After harvest, decontamination methods can be applied during transport, storage, or processing, but their application for aflatoxin reduction is still limited. Therefore, this review aims to investigate the effects of environmental factors on aflatoxin production because of climate change and to critically discuss the present-day and novel decontamination techniques to unravel gaps and limitations to propose them as a tool to tackle an increased aflatoxin risk in Europe.
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Affiliation(s)
- Martina Loi
- Institute of Sciences of Food Production, National Research Council, Bari, Italy,*Correspondence: Martina Loi, ✉
| | - Antonio F. Logrieco
- Institute of Sciences of Food Production, National Research Council, Bari, Italy
| | - Tünde Pusztahelyi
- Central Laboratory of Agricultural and Food Products, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Debrecen, Hungary
| | - Éva Leiter
- Department of Molecular Biotechnology and Microbiology, Faculty of Science and Technology, Institute of Biotechnology, University of Debrecen, Debrecen, Hungary,ELRN-UD Fungal Stress Biology Research Group, University of Debrecen, Debrecen, Hungary
| | - László Hornok
- Hungarian University of Agriculture and Life Sciences, Gödöllő, Hungary
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Faculty of Science and Technology, Institute of Biotechnology, University of Debrecen, Debrecen, Hungary,ELRN-UD Fungal Stress Biology Research Group, University of Debrecen, Debrecen, Hungary
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7
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Kumar P, Gupta A, Mahato DK, Pandhi S, Pandey AK, Kargwal R, Mishra S, Suhag R, Sharma N, Saurabh V, Paul V, Kumar M, Selvakumar R, Gamlath S, Kamle M, Enshasy HAE, Mokhtar JA, Harakeh S. Aflatoxins in Cereals and Cereal-Based Products: Occurrence, Toxicity, Impact on Human Health, and Their Detoxification and Management Strategies. Toxins (Basel) 2022; 14:toxins14100687. [PMID: 36287956 PMCID: PMC9609140 DOI: 10.3390/toxins14100687] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/27/2022] [Accepted: 09/28/2022] [Indexed: 11/08/2022] Open
Abstract
Cereals and cereal-based products are primary sources of nutrition across the world. However, contamination of these foods with aflatoxins (AFs), secondary metabolites produced by several fungal species, has raised serious concerns. AF generation in innate substrates is influenced by several parameters, including the substrate type, fungus species, moisture content, minerals, humidity, temperature, and physical injury to the kernels. Consumption of AF-contaminated cereals and cereal-based products can lead to both acute and chronic health issues related to physical and mental maturity, reproduction, and the nervous system. Therefore, the precise detection methods, detoxification, and management strategies of AFs in cereal and cereal-based products are crucial for food safety as well as consumer health. Hence, this review provides a brief overview of the occurrence, chemical characteristics, biosynthetic processes, health hazards, and detection techniques of AFs, along with a focus on detoxification and management strategies that could be implemented for food safety and security.
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Affiliation(s)
- Pradeep Kumar
- Department of Botany, University of Lucknow, Lucknow 226007, India
- Applied Microbiology Laboratory, Department of Forestry, North Eastern Regional Institute of Science and Technology, Nirjuli 791109, India
- Correspondence: (P.K.); (D.K.M.)
| | - Akansha Gupta
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Dipendra Kumar Mahato
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
- Correspondence: (P.K.); (D.K.M.)
| | - Shikha Pandhi
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Arun Kumar Pandey
- MMICT&BM(HM), Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala 133207, India
| | - Raveena Kargwal
- Department of Processing and Food Engineering, College of Agricultural Engineering and Technology, Chaudhary Charan Singh Haryana Agricultural University, Hisar 125004, India
| | - Sadhna Mishra
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
- Faculty of Agricultural Sciences, GLA University, Mathura 281406, India
| | - Rajat Suhag
- Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bolzano, Italy
| | - Nitya Sharma
- Food and Bioprocess Engineering Laboratory, Centre for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Vivek Saurabh
- Division of Food Science and Postharvest Technology, ICAR—Indian Agricultural Research Institute, New Delhi 110012, India
| | - Veena Paul
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Manoj Kumar
- Chemical and Biochemical Processing Division, ICAR—Central Institute for Research on Cotton Technology, Mumbai 400019, India
| | - Raman Selvakumar
- Centre for Protected Cultivation Technology, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi 110012, India
| | - Shirani Gamlath
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Madhu Kamle
- Applied Microbiology Laboratory, Department of Forestry, North Eastern Regional Institute of Science and Technology, Nirjuli 791109, India
| | - Hesham Ali El Enshasy
- Institute of Bioproduct Development, Universiti Teknologi Malaysia (UTM), Skudai 81310, Malaysia
- City of Scientific Research and Technology Applications, New Burg Al Arab, Alexandria 21934, Egypt
| | - Jawahir A. Mokhtar
- Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University Hospital, Jeddah 21589, Saudi Arabia
- Vaccines and Immunotherapy Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Steve Harakeh
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Yousef Abdul Latif Jameel Scientific Chair of Prophetic Medicine Application, Faculty of Medicine (FM), King Abdulaziz University, Jeddah 21589, Saudi Arabia
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8
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Yang K, Tian J, Keller NP. Post-translational modifications drive secondary metabolite biosynthesis in Aspergillus: a review. Environ Microbiol 2022; 24:2857-2881. [PMID: 35645150 PMCID: PMC9545273 DOI: 10.1111/1462-2920.16034] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 04/23/2022] [Accepted: 04/26/2022] [Indexed: 12/26/2022]
Abstract
Post‐translational modifications (PTMs) are important for protein function and regulate multiple cellular processes and secondary metabolites (SMs) in fungi. Aspergillus species belong to a genus renown for an abundance of bioactive secondary metabolites, many important as toxins, pharmaceuticals and in industrial production. The genes required for secondary metabolites are typically co‐localized in biosynthetic gene clusters (BGCs), which often localize in heterochromatic regions of genome and are ‘turned off’ under laboratory condition. Efforts have been made to ‘turn on’ these BGCs by genetic manipulation of histone modifications, which could convert the heterochromatic structure to euchromatin. Additionally, non‐histone PTMs also play critical roles in the regulation of secondary metabolism. In this review, we collate the known roles of epigenetic and PTMs on Aspergillus SM production. We also summarize the proteomics approaches and bioinformatics tools for PTM identification and prediction and provide future perspectives on the emerging roles of PTM on regulation of SM biosynthesis in Aspergillus and other fungi.
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Affiliation(s)
- Kunlong Yang
- School of Life Science, Jiangsu Normal University, Xuzhou, 221116, Jiangsu Province, People's Republic of China.,Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, 53705, USA
| | - Jun Tian
- School of Life Science, Jiangsu Normal University, Xuzhou, 221116, Jiangsu Province, People's Republic of China
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, 53705, USA
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9
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Buitimea-Cantúa GV, Magaña-Barajas E, Buitimea-Cantúa NE, Leija Gutiérrez HM, Del Refugio Rocha-Pizaña M, Rosas-Burgos EC, Hernández-Morales A, Molina-Torres J. Down-regulation of aflatoxin biosynthetic genes in Aspergillus parasiticus by Heliopsis longipes roots and affinin for reduction of aflatoxin production. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART. B, PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES 2021; 56:899-908. [PMID: 34487477 DOI: 10.1080/03601234.2021.1974273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Affinin present in Heliopsis longipes roots has been identified as an anti-aflatoxin molecule. However, its mechanism of action has yet to be clarified. Aflatoxins biosynthesis involves not less than 27 enzymatic reactions. In this work, the genes aflG, aflH, aflI, aflK, aflL, aflM, aflO, aflP, and aflQ of the aflatoxins cluster and the aflS gene encoding an internal regulatory factor involved in aflatoxins biosynthesis in Aspergillus parasiticus, were studied by qRT-PCR. Results demonstrated that ethanolic extract of H. longipes roots and affinin inhibit aflatoxin biosynthesis and fungal growth in a dose-dependent manner. At 300 µg/mL, ethanolic extract and affinin presented the highest inhibition of radial growth (86% and 94%) and aflatoxin production (68% and 80%). The qRT-PCR analysis demonstrated that nine tested genes were down-regulated by affinin and ethanolic extract. The most down-regulated was the aflK, a gene that encodes an enzyme cyclase with double function during the aflatoxin biosynthesis. While no significant down-regulation was obtaining for aflH gene. Exposure to affinin also resulted in decreased transcript levels of the internal regulator factor aflS. Based on our results, a model showing the regulatory mechanism in aflatoxin biosynthesis and its role in gene expression was proposed. In conclusion, affinin modulates the expression of several aflatoxin biosynthetic genes, leading to mycotoxin biosynthesis inhibition. Therefore, H. longipes roots is a suitable candidate to developed control strategies via lowering gene expressions as a future perspective in reducing aflatoxin contamination.
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Affiliation(s)
- Génesis V Buitimea-Cantúa
- Tecnologico de Monterrey, Centro de Biotecnología-FEMSA, Escuela de Ingeniería y Ciencias, Monterrey, Nuevo León, México
- Departamento de Biotecnología y Bioquímica, CINVESTAV, Irapuato, Guanajuato, México
| | - Elisa Magaña-Barajas
- Programa de Ingeniería en Tecnologías de Alimentos, Universidad Estatal de Sonora, Hermosillo, México
| | - Nydia E Buitimea-Cantúa
- Tecnologico de Monterrey, Centro de Biotecnología-FEMSA, Escuela de Ingeniería y Ciencias, Monterrey, Nuevo León, México
| | - Héctor Manuel Leija Gutiérrez
- Universidad Autónoma de Nuevo León, CICFM-Facultad de Ciencias Físico Matemáticas. San Nicolás de los Garza, NL, México
| | | | - Ema Carina Rosas-Burgos
- Departamento de Investigación y Posgrado en Alimentos, Universidad de Sonora, Hermosillo, Sonora, México
| | - Alejandro Hernández-Morales
- Facultad de Estudios Profesionales Zona Huasteca, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Jorge Molina-Torres
- Departamento de Biotecnología y Bioquímica, CINVESTAV, Irapuato, Guanajuato, México
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10
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Sharma S, Choudhary B, Yadav S, Mishra A, Mishra VK, Chand R, Chen C, Pandey SP. Metabolite profiling identified pipecolic acid as an important component of peanut seed resistance against Aspergillus flavus infection. JOURNAL OF HAZARDOUS MATERIALS 2021; 404:124155. [PMID: 33049626 DOI: 10.1016/j.jhazmat.2020.124155] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 09/03/2020] [Accepted: 09/28/2020] [Indexed: 06/11/2023]
Abstract
In a previous study, we identified a halotolerant rhizobacterium belonging to the genus Klebsiella (MBE02) that protected peanut seeds from Aspergillus flavus infection. Here, we investigated the mechanisms underlying the effect of MBE02 against A. flavus via untargeted metabolite profiling of peanut seeds treated with MBE02, A. flavus, or MBE02+A. flavus. Thirty-five metabolites were differentially accumulated across the three treatments (compared to the control), and the levels of pipecolic acid (Pip) were reduced upon A. flavus treatment only. We validated the function of Pip against A. flavus using multiple resistant and susceptible peanut cultivars. Pip accumulation was strongly associated with the resistant genotypes that also accumulated several mRNAs of the ALD1-like gene in the Pip biosynthesis pathway. Furthermore, exogenous treatment of a susceptible peanut cultivar with Pip reduced A. flavus infection in the seeds. Our findings indicate that Pip is a key component of peanut resistance to A. flavus.
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Affiliation(s)
- Sandeep Sharma
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India.
| | - Babita Choudhary
- CSIR-Central Salt & Marine Chemicals Research Institute, Bhavnagar, India.
| | - Sonam Yadav
- CSIR-Central Salt & Marine Chemicals Research Institute, Bhavnagar, India.
| | - Avinash Mishra
- CSIR-Central Salt & Marine Chemicals Research Institute, Bhavnagar, India.
| | - Vinod K Mishra
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India.
| | - Ramesh Chand
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India.
| | - Chen Chen
- Jiangsu Key Laboratory of Crop Genetics and Physiology, Co-Innovation Center for Modern Production Technology of Grain Crops, Key Laboratory of Plant Functional Genomics of the Ministry of Education, Yangzhou University, Yangzhou, China.
| | - Shree P Pandey
- Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena, Germany.
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11
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Nazhand A, Durazzo A, Lucarini M, Souto EB, Santini A. Characteristics, Occurrence, Detection and Detoxification of Aflatoxins in Foods and Feeds. Foods 2020; 9:E644. [PMID: 32443392 PMCID: PMC7278662 DOI: 10.3390/foods9050644] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 05/09/2020] [Accepted: 05/12/2020] [Indexed: 12/14/2022] Open
Abstract
Mycotoxin contamination continues to be a food safety concern globally, with the most toxic being aflatoxins. On-farm aflatoxins, during food transit or storage, directly or indirectly result in the contamination of foods, which affects the liver, immune system and reproduction after infiltration into human beings and animals. There are numerous reports on aflatoxins focusing on achieving appropriate methods for quantification, precise detection and control in order to ensure consumer safety. In 2012, the International Agency for Research on Cancer (IARC) classified aflatoxins B1, B2, G1, G2, M1 and M2 as group 1 carcinogenic substances, which are a global human health concern. Consequently, this review article addresses aflatoxin chemical properties and biosynthetic processes; aflatoxin contamination in foods and feeds; health effects in human beings and animals due to aflatoxin exposure, as well as aflatoxin detection and detoxification methods.
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Affiliation(s)
- Amirhossein Nazhand
- Department of Biotechnology, Sari Agricultural Science and Natural Resource University, 9th km of Farah Abad Road, Mazandaran 48181-68984, Iran;
| | - Alessandra Durazzo
- CREA-Research Centre for Food and Nutrition, Via Ardeatina 546, 00178 Roma, Italy; (A.D.); (M.L.)
| | - Massimo Lucarini
- CREA-Research Centre for Food and Nutrition, Via Ardeatina 546, 00178 Roma, Italy; (A.D.); (M.L.)
| | - Eliana B. Souto
- Faculty of Pharmacy of University of Coimbra, Azinhaga de Santa Comba, Polo III-Saúde, 3000-548 Coimbra, Portugal;
- CEB-Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Antonello Santini
- Department of Pharmacy, University of Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy
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12
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Aflatoxin Biosynthesis and Genetic Regulation: A Review. Toxins (Basel) 2020; 12:toxins12030150. [PMID: 32121226 PMCID: PMC7150809 DOI: 10.3390/toxins12030150] [Citation(s) in RCA: 134] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/27/2020] [Accepted: 02/25/2020] [Indexed: 12/15/2022] Open
Abstract
The study of fungal species evolved radically with the development of molecular techniques and produced new evidence to understand specific fungal mechanisms such as the production of toxic secondary metabolites. Taking advantage of these technologies to improve food safety, the molecular study of toxinogenic species can help elucidate the mechanisms underlying toxin production and enable the development of new effective strategies to control fungal toxicity. Numerous studies have been made on genes involved in aflatoxin B1 (AFB1) production, one of the most hazardous carcinogenic toxins for humans and animals. The current review presents the roles of these different genes and their possible impact on AFB1 production. We focus on the toxinogenic strains Aspergillus flavus and A. parasiticus, primary contaminants and major producers of AFB1 in crops. However, genetic reports on A. nidulans are also included because of the capacity of this fungus to produce sterigmatocystin, the penultimate stable metabolite during AFB1 production. The aim of this review is to provide a general overview of the AFB1 enzymatic biosynthesis pathway and its link with the genes belonging to the AFB1 cluster. It also aims to illustrate the role of global environmental factors on aflatoxin production and the recent data that demonstrate an interconnection between genes regulated by these environmental signals and aflatoxin biosynthetic pathway.
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13
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Lyhs U, Frandsen H, Andersen B, Nonnemann B, Hjulsager C, Pedersen K, Chriél M. Microbiological quality of mink feed raw materials and feed production area. Acta Vet Scand 2019; 61:56. [PMID: 31752948 PMCID: PMC6873557 DOI: 10.1186/s13028-019-0489-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 10/30/2019] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND The quality of mink feed and raw ingredients affect health and growth. The objectives of this study were to examine the microbiological quality of ready-to-eat mink feed and its raw ingredients, screen the plant part of the feed for mycotoxins, and determine the hygiene of the production environment in the feed processing facilities. The results of the study are important for identification of critical steps in the feed production and for formulation of recommendations for improvements of production processes to obtain better quality feed. Feed and swab samples were taken at three Danish mink feed producers October 2016 and May 2017, respectively. Viable counts, detection of methicillin-resistant Staphylococcus aureus (MRSA), influenza virus and filamentous fungi were performed together with qualitative chemical analyses for bioactive fungal metabolites and mycotoxins. Swab samples were analyzed for total viable counts. RESULTS Viable counts varied between 7.2 × 102 and 9.3 × 107 cfu/g in raw ingredients and between 107 and 109 cfu/cm2 on different surfaces at the feed production facilities. A pork meat product, pork haemoglobin, pork liver and a poultry mix was found positive for MRSA, while monophasic Salmonella [4,5,12:i:-] was detected in a pork meat product. Neither MRSA nor Salmonella was detected in any ready-to-eat feed. Influenza A virus was not detected in any sample. Filamentous fungi were detected in all analysed samples of ready-to-eat feed while dihydro-demethyl-sterigmatocystin was found in almost 50% of all ready-to-eat feed samples and in 80% of the sugar beet pulp. Fumonisins and other Fusarium toxins were found especially in corn gluten meal and extruded barley and wheat. CONCLUSIONS Mink feed contained a cocktail of mycotoxins and bacteria, which may not per se cause clinical disease, but may affect organ function and animal performance and well-being.
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Affiliation(s)
- Ulrike Lyhs
- National Veterinary Institute, Technical University of Denmark, Kemitorvet, Building 202, 2800 Kgs. Lyngby, Denmark
- Present Address: Institute for Molecular Medicine Finland (FIMM), University of Helsinki, P.O.Box 20, Tukholmankatu 8, 00014 Helsinki, Finland
| | - Henrik Frandsen
- National Food Institute, Technical University of Denmark, Kemitorvet, Building 202, 2800 Kgs. Lyngby, Denmark
| | - Birgitte Andersen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, 2800 Kgs. Lyngby, Denmark
| | - Bettina Nonnemann
- National Veterinary Institute, Technical University of Denmark, Kemitorvet, Building 202, 2800 Kgs. Lyngby, Denmark
| | - Charlotte Hjulsager
- National Veterinary Institute, Technical University of Denmark, Kemitorvet, Building 202, 2800 Kgs. Lyngby, Denmark
- Present Address: Statens Serum Institut, Artillerivej 5, 2300 Copenhagen S, Denmark
| | - Karl Pedersen
- Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, Ulls väg 2B, 751 89 Uppsala, Sweden
| | - Mariann Chriél
- National Veterinary Institute, Technical University of Denmark, Kemitorvet, Building 202, 2800 Kgs. Lyngby, Denmark
- Present Address: Environmental Protection Agency, Tolderlundvej 5, 5000 Odense C, Denmark
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14
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Genetic Diversity of Fungi Producing Mycotoxins in Stored Crops. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2018. [DOI: 10.22207/jpam.12.4.15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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15
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Ámon J, Keisham K, Bokor E, Kelemen E, Vágvölgyi C, Hamari Z. Sterigmatocystin production is restricted to hyphae located in the proximity of hülle cells. J Basic Microbiol 2018; 58:590-596. [PMID: 29733450 DOI: 10.1002/jobm.201800020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/19/2018] [Accepted: 04/22/2018] [Indexed: 12/20/2022]
Abstract
Aspergillus nidulans produces sterigmatocystin, a secondary metabolite mycotoxin, for the protection of its reproductive structures. Previous studies on grazing behavior of fungivore arthropods, regulation of sexual development, and secondary metabolite biosynthesis have revealed the association of sterigmatocystin biosynthesis with sexual reproduction, but the spatial distribution of sterigmatocystin producing hyphae within the colony has never been investigated. In this work, we aimed to locate the site of sterigmatocystin production within the colony by employing a yCFP reporter system. We demonstrated that the stcO promoter is active only in vegetative hyphae that surround groups of hülle cells and the activity decreases and eventually ceases as the distance between the hypha and the hülle cells increases. This phenomenon indicates that the vegetative mycelium might consist of morphologically uniform, but functionally different hyphae.
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Affiliation(s)
- Judit Ámon
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Kabichandra Keisham
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Eszter Bokor
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Evelyn Kelemen
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Csaba Vágvölgyi
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Zsuzsanna Hamari
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
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16
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Metabolites Identified during Varied Doses of Aspergillus Species in Zea mays Grains, and Their Correlation with Aflatoxin Levels. Toxins (Basel) 2018; 10:toxins10050187. [PMID: 29735944 PMCID: PMC5983243 DOI: 10.3390/toxins10050187] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 04/30/2018] [Accepted: 05/04/2018] [Indexed: 11/16/2022] Open
Abstract
Aflatoxin contamination is associated with the development of aflatoxigenic fungi such as Aspergillus flavus and A. parasiticus on food grains. This study was aimed at investigating metabolites produced during fungal development on maize and their correlation with aflatoxin levels. Maize cobs were harvested at R3 (milk), R4 (dough), and R5 (dent) stages of maturity. Individual kernels were inoculated in petri dishes with four doses of fungal spores. Fungal colonisation, metabolite profile, and aflatoxin levels were examined. Grain colonisation decreased with kernel maturity: milk-, dough-, and dent-stage kernels by approximately 100%, 60%, and 30% respectively. Aflatoxin levels increased with dose at dough and dent stages. Polar metabolites including alanine, proline, serine, valine, inositol, iso-leucine, sucrose, fructose, trehalose, turanose, mannitol, glycerol, arabitol, inositol, myo-inositol, and some intermediates of the tricarboxylic acid cycle (TCA—also known as citric acid or Krebs cycle) were important for dose classification. Important non-polar metabolites included arachidic, palmitic, stearic, 3,4-xylylic, and margaric acids. Aflatoxin levels correlated with levels of several polar metabolites. The strongest positive and negative correlations were with arabitol (R = 0.48) and turanose and (R = −0.53), respectively. Several metabolites were interconnected with the TCA; interconnections of the metabolites with the TCA cycle varied depending upon the grain maturity.
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17
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Sadhasivam S, Britzi M, Zakin V, Kostyukovsky M, Trostanetsky A, Quinn E, Sionov E. Rapid Detection and Identification of Mycotoxigenic Fungi and Mycotoxins in Stored Wheat Grain. Toxins (Basel) 2017; 9:toxins9100302. [PMID: 28946706 PMCID: PMC5666349 DOI: 10.3390/toxins9100302] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 02/06/2023] Open
Abstract
This study aimed to assess the occurrence of toxigenic fungi and mycotoxin contamination in stored wheat grains by using advanced molecular and analytical techniques. A multiplex polymerase chain reaction (PCR) strategy was established for rapid identification of mycotoxigenic fungi, and an improved analytical method was developed for simultaneous multi-mycotoxin determination in wheat grains by liquid chromatography-tandem mass spectrometry (LC/MS/MS) without the need for any clean-up. The optimized multiplex PCR method was highly specific in detecting fungal species containing species-specific and mycotoxin metabolic pathway genes. The method was applied for evaluation of 34 wheat grain samples collected from storage warehouses for the presence of mycotoxin-producing fungi, and a few samples were found positive for Fusarium and Aspergillus species. Further chemical analysis revealed that 17 samples contained mycotoxins above the level of detection, but only six samples were found to be contaminated over the EU regulatory limits with at least one mycotoxin. Aflatoxin B1, fumonisins, and deoxynivalenol were the most common toxins found in these samples. The results showed a strong correlation between the presence of mycotoxin biosynthesis genes as analyzed by multiplex PCR and mycotoxin detection by LC/MS/MS. The present findings indicate that a combined approach might provide rapid, accurate, and sensitive detection of mycotoxigenic species and mycotoxins in wheat grains.
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Affiliation(s)
- Sudharsan Sadhasivam
- Department of Food Quality and Safety, Institute for Postharvest and Food Sciences, Agricultural Research Organization, The Volcani Center, Rishon LeZion 7528809, Israel.
| | - Malka Britzi
- National Residue Control Laboratory, Kimron Veterinary Institute, Bet Dagan 50250, Israel.
| | - Varda Zakin
- Department of Food Quality and Safety, Institute for Postharvest and Food Sciences, Agricultural Research Organization, The Volcani Center, Rishon LeZion 7528809, Israel.
| | - Moshe Kostyukovsky
- Department of Food Quality and Safety, Institute for Postharvest and Food Sciences, Agricultural Research Organization, The Volcani Center, Rishon LeZion 7528809, Israel.
| | - Anatoly Trostanetsky
- Department of Food Quality and Safety, Institute for Postharvest and Food Sciences, Agricultural Research Organization, The Volcani Center, Rishon LeZion 7528809, Israel.
| | - Elazar Quinn
- Department of Food Quality and Safety, Institute for Postharvest and Food Sciences, Agricultural Research Organization, The Volcani Center, Rishon LeZion 7528809, Israel.
| | - Edward Sionov
- Department of Food Quality and Safety, Institute for Postharvest and Food Sciences, Agricultural Research Organization, The Volcani Center, Rishon LeZion 7528809, Israel.
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18
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Degeneration of aflatoxin gene clusters in Aspergillus flavus from Africa and North America. AMB Express 2016; 6:62. [PMID: 27576895 PMCID: PMC5005231 DOI: 10.1186/s13568-016-0228-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 08/12/2016] [Indexed: 01/07/2023] Open
Abstract
Aspergillus flavus is the most common causal agent of aflatoxin contamination of food and feed. However, aflatoxin-producing potential varies widely among A. flavus genotypes with many producing no aflatoxins. Some non-aflatoxigenic genotypes are used as biocontrol agents to prevent contamination. Aflatoxin biosynthesis genes are tightly clustered in a highly conserved order. Gene deletions and presence of single nucleotide polymorphisms (SNPs) in aflatoxin biosynthesis genes are often associated with A. flavus inability to produce aflatoxins. In order to identify mechanisms of non-aflatoxigenicity in non-aflatoxigenic genotypes of value in aflatoxin biocontrol, complete cluster sequences of 35 A. flavus genotypes from Africa and North America were analyzed. Inability of some genotypes to produce aflatoxin resulted from deletion of biosynthesis genes. In other genotypes, non-aflatoxigenicity originated from SNP formation. The process of degeneration differed across the gene cluster; genes involved in early biosynthesis stages were more likely to be deleted while genes involved in later stages displayed high frequencies of SNPs. Comparative analyses of aflatoxin gene clusters provides insight into the diversity of mechanisms of non-aflatoxigenicity in A. flavus genotypes used as biological control agents. The sequences provide resources for both diagnosis of non-aflatoxigenicity and monitoring of biocontrol genotypes during biopesticide manufacture and in the environment.
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19
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Baquião AC, Lopes EL, Corrêa B. Molecular and mycotoxigenic biodiversity of Aspergillus flavus isolated from Brazil nuts. Food Res Int 2016; 89:266-271. [PMID: 28460913 DOI: 10.1016/j.foodres.2016.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/14/2016] [Accepted: 08/07/2016] [Indexed: 01/20/2023]
Abstract
The objective of this study was to carry out a transcription analysis of eight genes belonging to the aflatoxin (AF) and cyclopiazonic acid (CPA) biosynthesis pathway, and to detect aflatoxin B1 (AFB1) and CPA production in Aspergillus flavus strains isolated from Brazil nuts. Additionally, these genes were correlated with the different mycotoxigenic profiles of the same strains. Four previously identified A. flavus strains (ICB-01, ICB-151, ICB-161, and ICB-165) were grown on Brazil nut agar at 25°C for 10days. Mycotoxins were separated by high-performance liquid chromatography. Transcriptional analysis was performed by real-time RT-PCR using specific primers designed based on the conserved regions of two regulatory genes (aflR and aflS), three structural genes of the AFB1 biosynthesis pathway (aflH, aflJ and aflP), and three structural genes of the CPA biosynthesis pathway (maoA, dmaT and pks-nrps). The expression of most genes in the A. flavus isolates varied according to the mycotoxin profile of each strain. The most expressed genes in the aflatoxigenic strain ICB-151 were aflJ (77.11%) and aflH (32.75%), while the CPA-producing strain ICB-161 mainly expressed dmaT (100%), maoA (63.72%), aflS (43.52%), and aflR (42.63%). The ICB-01 isolate was a producer of AFB1 and CPA and the most expressed genes were aflS (47.79%), dmaT (42.77%), aflP (39.5%), and aflR (38.02%). ICB-198 did not produce any mycotoxin and exhibited lower expression of almost all genes analyzed. Furthermore, the ratio of aflS/aflR expression was correlated with the biosynthesis of AF and CPA in A. flavus strains producing exclusively AF or CPA or producing both AF and CPA. The ratio of aflS/aflR expression therefore seems to be related to the production of mycotoxins in Brazil nuts. Our results provide important data for the development of innovative and more cost-effective strategies to reduce and prevent AFB and CPA contamination in Brazil nuts.
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Affiliation(s)
- Arianne Costa Baquião
- Departamento de Microbiologia, Instituto de Ciências Biomédicas II, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, CEP 05508-000 São Paulo, Brazil.
| | - Evandro Luiz Lopes
- Escola Paulista de Política, Economia e Negócios, Universidade Federal de São Paulo, Brazil
| | - Benedito Corrêa
- Departamento de Microbiologia, Instituto de Ciências Biomédicas II, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, CEP 05508-000 São Paulo, Brazil
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20
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Awakawa T, Yang XL, Wakimoto T, Abe I. Pyranonigrin E: A PKS-NRPS Hybrid Metabolite fromAspergillus nigerIdentified by Genome Mining. Chembiochem 2013; 14:2095-9. [DOI: 10.1002/cbic.201300430] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Indexed: 01/05/2023]
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21
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Yu J. Current understanding on aflatoxin biosynthesis and future perspective in reducing aflatoxin contamination. Toxins (Basel) 2012; 4:1024-57. [PMID: 23202305 PMCID: PMC3509697 DOI: 10.3390/toxins4111024] [Citation(s) in RCA: 197] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 10/08/2012] [Accepted: 10/09/2012] [Indexed: 01/20/2023] Open
Abstract
Traditional molecular techniques have been used in research in discovering the genes and enzymes that are involved in aflatoxin formation and genetic regulation. We cloned most, if not all, of the aflatoxin pathway genes. A consensus gene cluster for aflatoxin biosynthesis was discovered in 2005. The factors that affect aflatoxin formation have been studied. In this report, the author summarized the current status of research progress and future possibilities that may be used for solving aflatoxin contamination.
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Affiliation(s)
- Jiujiang Yu
- Southern Regional Research Center, Agricultural Research Service, United States Department of Agriculture (USDA/ARS), New Orleans, LA 70112, USA.
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22
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Levin RE. PCR detection of aflatoxin producing fungi and its limitations. Int J Food Microbiol 2012; 156:1-6. [PMID: 22445201 DOI: 10.1016/j.ijfoodmicro.2012.03.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 02/08/2012] [Accepted: 03/01/2012] [Indexed: 10/28/2022]
Abstract
Unlike bacterial toxins that are primarily peptides and are therefore encoded by a single gene, fungal toxins such as the aflatoxins are multi-ring structures and therefore require a sequence of structural genes for their biological synthesis. There is therefore no specific PCR for any one of the four biologically produced aflatoxins. Unfortunately, the structural genes presently in use for PCR detection of aflatoxin producing fungi are also involved in the synthesis of other fungal toxins such as sterigmatocystin by Aspergillus versicolor and Aspergillus nidulans and therefore lack absolute specificity for aflatoxin producing fungi (Table 1). In addition, the genomic presence of several structural genes involved in aflatoxin biosynthesis does not guarantee the production of aflatoxin by all isolates of Aspergillus flavus and Aspergillus parasiticus. The most widely used DNA target regions for discriminating Aspergillus species are those of the rDNA complex, mainly the internal transcribed spacer regions 1 and 2 (ITS1 and ITS2) and the variable regions in the 5'-end of the 28S rRNA gene. Since these sequence regions are unrelated to the structural genes involved in aflatoxin biosynthesis there successful amplification can be used for species identification but do not confirm aflatoxin production. This review therefore presents the various approaches and limitations in the use of the PCR in attempting to detect aflatoxin producing fungi.
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Affiliation(s)
- Robert E Levin
- Department of Food Science, Massachusetts Agricultural Experiment Station, University of Massachusetts, Amherst, MA 01003, USA.
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23
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YABE K, NAKAJIMA H. Aflatoxin Biosynthesis. Food Hygiene and Safety Science (Shokuhin Eiseigaku Zasshi) 2011; 52:135-47. [DOI: 10.3358/shokueishi.52.135] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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24
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Ehrlich K, Wei Q, Bhatnagar D. Increased sensitivity of Aspergillus flavus and Aspergillus parasiticus aflatoxin biosynthesis polyketide synthase mutants to UVB light. WORLD MYCOTOXIN J 2010. [DOI: 10.3920/wmj2010.1218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
One strategy to reduce aflatoxin contamination of maize and cottonseed is to introduce spores of non-aflatoxigenic strains as competitors. Using isogenic mutants we show that, upon 5 or 20 min exposure to 302 nm (UVB) light, the viability of conidia of Aspergillus flavus and Aspergillus parasiticus mutants lacking the ability to accumulate any aflatoxin precursor metabolite is reduced five-fold compared to that of aflatoxin-producing strains or pigmented mutants that accumulate aflatoxin precursors. This result suggests that the long-term viability of introduced non-aflatoxigenic competitor strains may be lower than that of natural aflatoxin-producing isolates when exposed to sunlight.
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Affiliation(s)
- K. Ehrlich
- Southern Regional Research Center, ARS, USDA, 1100 Robert E. Lee Blvd, New Orleans, LA 70124, USA
| | - Q. Wei
- Southern Regional Research Center, ARS, USDA, 1100 Robert E. Lee Blvd, New Orleans, LA 70124, USA
| | - D. Bhatnagar
- Southern Regional Research Center, ARS, USDA, 1100 Robert E. Lee Blvd, New Orleans, LA 70124, USA
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25
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Donner M, Atehnkeng J, Sikora R, Bandyopadhyay R, Cotty P. Molecular characterization of atoxigenic strains for biological control of aflatoxins in Nigeria. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2010; 27:576-90. [DOI: 10.1080/19440040903551954] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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26
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Ehrlich KC. Predicted roles of the uncharacterized clustered genes in aflatoxin biosynthesis. Toxins (Basel) 2009; 1:37-58. [PMID: 22069531 PMCID: PMC3202775 DOI: 10.3390/toxins1010037] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 09/22/2009] [Accepted: 09/24/2009] [Indexed: 11/21/2022] Open
Abstract
Biosynthesis of the toxic and carcinogenic aflatoxins (AFs) requires the activity of more than 27 enzymes. The roles in biosynthesis of newly described enzymes are discussed in this review. We suggest that HypC catalyzes the oxidation of norsolorinic acid anthrone; AvfA (AflI), the ring-closure step in formation of hydroxyversicolorone; HypB, the second oxidation step in conversion of O-methylsterigmatocystin to AF; and HypE and NorA (AflE), the final two steps in AFB(1) formation. HypD, an integral membrane protein, affects fungal development and lowers AF production while AflJ (AflS), has a partial methyltransferase domain that may be important in its function as a transcriptional co-activator.
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Affiliation(s)
- Kenneth C Ehrlich
- Southern Regional Research Center, ARS, USDA/1100 Robert E. Lee Blvd, New Orleans, LA 70124, USA.
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Peña-Montes C, Lange S, Flores I, Castro-Ochoa D, Schmid R, Cruz-García F, Farrés A. Molecular characterization of StcI esterase from Aspergillus nidulans. Appl Microbiol Biotechnol 2009; 84:917-26. [PMID: 19440704 DOI: 10.1007/s00253-009-2005-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 04/01/2009] [Accepted: 04/07/2009] [Indexed: 11/24/2022]
Abstract
Aspergillus nidulans produces StcI esterase, which is involved in the biosynthesis of sterigmatocystin, a precursor of aflatoxins. Previous reports of this esterase in A. nidulans suggest that it is composed of 286 amino acid residues with a theoretical molecular mass of 31 kDa. Various conditions were evaluated to determine the optimal expression conditions for StcI; the highest level was observed when A. nidulans was cultured in solid oat media. Various esterases were expressed differentially according to the culture media used. However, specific antibodies designed to detect StcI reacted with a protein with an unexpected molecular mass of 35 kDa in cell extracts from all expression conditions. Analysis of the gene sequence and already reported expressed sequence tags indicated the presence of an additional 29-amino-acid N-terminal region of StcI, which is not a signal peptide and which has not been previously reported. We also detected the presence of this additional N-terminal region using reverse-transcriptase polymerase chain reaction. The complete protein (NStcI) was cloned and successfully expressed in Pichia pastoris.
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Affiliation(s)
- Carolina Peña-Montes
- Food and Biotechnology Department, Chemistry Faculty, National Autonomous University of Mexico , Ciudad Universitaria, Mexico City, DF 04510, Mexico
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Cleveland TE, Yu J, Bhatnagar D, Chen Z, Brown RL, Chang P, Cary JW. Progress in Elucidating the Molecular Basis of the Host Plant—AspergillusFlavusInteraction, a Basis for Devising Strategies to Reduce Aflatoxin Contamination in Crops. ACTA ACUST UNITED AC 2008. [DOI: 10.1081/txr-200027892] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Collemare J, Pianfetti M, Houlle AE, Morin D, Camborde L, Gagey MJ, Barbisan C, Fudal I, Lebrun MH, Böhnert HU. Magnaporthe grisea avirulence gene ACE1 belongs to an infection-specific gene cluster involved in secondary metabolism. THE NEW PHYTOLOGIST 2008; 179:196-208. [PMID: 18433432 DOI: 10.1111/j.1469-8137.2008.02459.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The avirulence gene ACE1 from the rice blast fungus Magnaporthe grisea encodes a polyketide synthase (PKS) fused to a nonribosomal peptide synthetase (NRPS) probably involved in the biosynthesis of a secondary metabolite recognized by Pi33 resistant rice (Oryza sativa) cultivars. Analysis of the M. grisea genome revealed that ACE1 is located in a cluster of 15 genes, of which 14 are potentially involved in secondary metabolism as they encode enzymes such as a second PKS-NRPS (SYN2), two enoyl reductases (RAP1 and RAP2) and a putative Zn(II)(2)Cys(6) transcription factor (BC2). These 15 genes are specifically expressed during penetration into the host plant, defining an infection-specific gene cluster. A pORF3-GFP transcriptional fusion showed that the highly expressed ORF3 gene from the ACE1 cluster is only expressed in appressoria, as is ACE1. Phenotypic analysis of deletion or disruption mutants of SYN2 and RAP2 showed that they are not required for avirulence in Pi33 rice cultivars, unlike ACE1. Inactivation of other genes was unsuccessful because targeted gene replacement and disruption were inefficient at this locus. Overall, the ACE1 gene cluster displays an infection-specific expression pattern restricted to the penetration stage which is probably controlled at the transcriptional level and reflects regulatory networks specific to early stages of infection.
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Affiliation(s)
- Jérôme Collemare
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
| | - Mikaël Pianfetti
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
| | - Anne-Elodie Houlle
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
| | - Damien Morin
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
| | - Laurent Camborde
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
| | - Marie-Josèphe Gagey
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
| | - Crystel Barbisan
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
| | - Isabelle Fudal
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
| | - Marc-Henri Lebrun
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
| | - Heidi U Böhnert
- UMR5240 CNRS/UCB/INSA/BAYER CropScience, 14-20 Rue Pierre Baizet, 69263 Lyon cedex 09, France
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Jørgensen TR. Identification and toxigenic potential of the industrially important fungi, Aspergillus oryzae and Aspergillus sojae. J Food Prot 2007; 70:2916-34. [PMID: 18095455 DOI: 10.4315/0362-028x-70.12.2916] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mold strains belonging to the species Aspergillus oryzae and Aspergillus sojae are highly valued as koji molds in the traditional preparation of fermented foods, such as miso, sake, and shoyu, and as protein production hosts in modern industrial processes. A. oryzae and A. sojae are relatives of the wild molds Aspergillus flavus and Aspergillus parasiticus. All four species are classified to the A. flavus group. Strains of the A. flavus group are characterized by a high degree of morphological similarity. Koji mold species are generally perceived of as being nontoxigenic, whereas wild molds are associated with the carcinogenic aflatoxins. Thus, reliable identification of individual strains is very important for application purposes. This review considers the pheno- and genotypic markers used in the classification of A. flavus group strains and specifically in the identification of A. oryzae and A. sojae strains. Separation of A. oryzae and A. sojae from A. flavus and A. parasiticus, respectively, is inconsistent, and both morphologic and molecular evidence support conspecificity. The high degree of identity is reflected by the divergent identification of reference cultures maintained in culture collections. As close relatives of aflatoxin-producing wild molds, koji molds possess an aflatoxin gene homolog cluster. Some strains identified as A. oryzae and A. sojae have been implicated in aflatoxin production. Identification of a strain as A. oryzae or A. sojae is no guarantee of its inability to produce aflatoxins or other toxic metabolites. Toxigenic potential must be determined specifically for individual strains. The species taxa, A. oryzae and A. sojae, are currently conserved by societal issues.
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Affiliation(s)
- Thomas R Jørgensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
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Chang PK, Matsushima K, Takahashi T, Yu J, Abe K, Bhatnagar D, Yuan GF, Koyama Y, Cleveland TE. Understanding nonaflatoxigenicity of Aspergillus sojae: a windfall of aflatoxin biosynthesis research. Appl Microbiol Biotechnol 2007; 76:977-84. [PMID: 17665189 DOI: 10.1007/s00253-007-1116-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Accepted: 07/07/2007] [Indexed: 10/23/2022]
Abstract
Aspergillus section Flavi includes aflatoxin-producing and nonproducing fungi. Aspergillus sojae is unable to produce aflatoxins and is generally recognized as safe for food fermentation. However, because of its taxonomical relatedness to aflatoxin-producing Aspergillus parasiticus and A. flavus, it is necessary to decipher the underlying mechanisms for its inability to produce aflatoxins. This review addresses the relationship between A. sojae and A. parasiticus and the advances that have been made in aflatoxin biosynthesis research, especially with regard to gene structure, genome organization, and gene regulation in A. parasiticus and A. flavus and how this has been used to assure the safety of A. sojae as an organism for food fermentation. The lack of aflatoxin-producing ability of A. sojae results primarily from an early termination point mutation in the pathway-specific aflR regulatory gene, which causes the truncation of the transcriptional activation domain of AflR and the abolishment of interaction between AflR and the AflJ co-activator. Both are required for gene expression. In addition, a defect in the polyketide synthase gene also contributes to its nonaflatoxigenicity.
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Affiliation(s)
- Perng-Kuang Chang
- Food and Feed Safety Research Unit, Southern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124, USA.
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Smith CA, Woloshuk CP, Robertson D, Payne GA. Silencing of the aflatoxin gene cluster in a diploid strain of Aspergillus flavus is suppressed by ectopic aflR expression. Genetics 2007; 176:2077-86. [PMID: 17565943 PMCID: PMC1950615 DOI: 10.1534/genetics.107.073460] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Aflatoxins are toxic secondary metabolites produced by a 70-kb cluster of genes in Aspergillus flavus. The cluster genes are coordinately regulated and reside as a single copy within the genome. Diploids between a wild-type strain and a mutant (649) lacking the aflatoxin gene cluster fail to produce aflatoxin or transcripts of the aflatoxin pathway genes. This dominant phenotype is rescued in diploids between a wild-type strain and a transformant of the mutant containing an ectopic copy of aflR, the transcriptional regulator of the aflatoxin biosynthetic gene cluster. Further characterization of the mutant showed that it is missing 317 kb of chromosome III, including the known genes for aflatoxin biosynthesis. In addition, 939 kb of chromosome II is present as a duplication on chromosome III in the region previously containing the aflatoxin gene cluster. The lack of aflatoxin production in the diploid was not due to a unique or a mis-expressed repressor of aflR. Instead a form of reversible silencing based on the position of aflR is likely preventing the aflatoxin genes from being expressed in 649 x wild-type diploids. Gene expression analysis revealed the silencing effect is specific to the aflatoxin gene cluster.
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Affiliation(s)
- Carrie A. Smith
- Department of Genetics, Department of Plant Biology and Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695 and Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
| | - Charles P. Woloshuk
- Department of Genetics, Department of Plant Biology and Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695 and Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
| | - Dominique Robertson
- Department of Genetics, Department of Plant Biology and Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695 and Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
| | - Gary A. Payne
- Department of Genetics, Department of Plant Biology and Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695 and Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
- Corresponding author: Center for Integrated Fungal Research and Department of Plant Pathology, North Carolina State University, Box 7567, Raleigh, NC 27695-7567.E-mail:
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Frisvad JC, Larsen TO, de Vries R, Meijer M, Houbraken J, Cabañes FJ, Ehrlich K, Samson RA. Secondary metabolite profiling, growth profiles and other tools for species recognition and important Aspergillus mycotoxins. Stud Mycol 2007; 59:31-7. [PMID: 18490955 PMCID: PMC2275202 DOI: 10.3114/sim.2007.59.04] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Species in the genus Aspergillus have been classified primarily based on morphological features. Sequencing of house-hold genes has also been used in Aspergillus taxonomy and phylogeny, while extrolites and physiological features have been used less frequently. Three independent ways of classifying and identifying aspergilli appear to be applicable: Morphology combined with physiology and nutritional features, secondary metabolite profiling and DNA sequencing. These three ways of identifying Aspergillus species often point to the same species. This consensus approach can be used initially, but if consensus is achieved it is recommended to combine at least two of these independent ways of characterising aspergilli in a polyphasic taxonomy. The chemical combination of secondary metabolites and DNA sequence features has not been explored in taxonomy yet, however. Examples of these different taxonomic approaches will be given for Aspergillus section Nigri.
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Affiliation(s)
- J C Frisvad
- Center for Microbial Biotechnology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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Abstract
Dothistromin is a mycotoxin that is remarkably similar in structure to versicolorin B, a precursor of both aflatoxin and sterigmatocystin. Dothistromin-producing fungi also produce related compounds, including some aflatoxin precursors as well as alternative forms of dothistromin. Dothistromin is synthesized by pathogenic species of Dothistroma in the red bands of pine needles associated with needle blight, but is also made in culture where it is strongly secreted into the surrounding medium. Orthologs of aflatoxin and sterigmatocystin biosynthetic genes have been found that are required for the biosynthesis of dothistromin, along with others that are speculated to be involved in the same pathway on the basis of their sequence similarity to aflatoxin genes. An epoxide hydrolase gene that has no homolog in the aflatoxin or sterigmatocystin gene clusters is also clustered with the dothistromin genes, and all these genes appear to be located on a minichromosome in Dothistroma septosporum. The dothistromin genes are expressed at an early stage of growth, suggesting a role in the first stages of plant invasion by the fungus. Future studies are expected to reveal more about the role of dothistromin in needle blight and about the genomic organization and expression of dothistromin genes: these studies will provide for interesting comparisons with these aspects of aflatoxin and sterigmatocystin biosynthesis.
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Affiliation(s)
- Rosie E Bradshaw
- National Centre for Advanced Bio-Protection Technologies, Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand.
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Bradshaw RE, Jin H, Morgan BS, Schwelm A, Teddy OR, Young CA, Zhang S. A polyketide synthase gene required for biosynthesis of the aflatoxin-like toxin, dothistromin. Mycopathologia 2006; 161:283-94. [PMID: 16649078 DOI: 10.1007/s11046-006-0240-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Accepted: 02/08/2006] [Indexed: 11/26/2022]
Abstract
Dothistromin is a polyketide toxin, produced by a fungal forest pathogen, with structural similarity to the aflatoxin precursor versicolorin B. Biochemical and genetic studies suggested that there are common steps in the biosynthetic pathways for these metabolites and showed similarities between some of the genes. A polyketide synthase gene (pksA) was isolated from dothistromin-producing Dothistroma septosporum by hybridization with an aflatoxin ortholog from Aspergillus parasiticus. Inactivation of this gene in D. septosporum resulted in mutants that could not produce dothistromin but that could convert exogenous aflatoxin precursors, including norsolorinic acid, into dothistromin. The mutants also had reduced asexual sporulation compared to the wild type. So far four other genes are known to be clustered immediately alongside pksA. Three of these (cypA, moxA, avfA) are predicted to be orthologs of aflatoxin biosynthetic genes. The other gene (epoA), located between avfA and moxA, is predicted to encode an epoxide hydrolase, for which there is no homolog in either the aflatoxin or sterigmatocystin gene clusters. The pksA gene is located on a small chromosome of approximately 1.3 Mb in size, along with the dothistromin ketoreductase (dotA) gene.
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Affiliation(s)
- Rosie E Bradshaw
- National Centre for Advanced Bio-Protection Technologies, Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand.
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Cary JW, Ehrlich KC, Bland JM, Montalbano BG. The aflatoxin biosynthesis cluster gene, aflX, encodes an oxidoreductase involved in conversion of versicolorin A to demethylsterigmatocystin. Appl Environ Microbiol 2006; 72:1096-101. [PMID: 16461654 PMCID: PMC1392920 DOI: 10.1128/aem.72.2.1096-1101.2006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biosynthesis of the toxic and carcinogenic aflatoxins by the fungus Aspergillus flavus is a complicated process involving more that 27 enzymes and regulatory factors encoded by a clustered group of genes. Previous studies found that three enzymes, encoded by verA, ver-1, and aflY, are required for conversion of versicolorin A (VA), to demethylsterigmatocystin. We now show that a fourth enzyme, encoded by the previously uncharacterized gene, aflX (ordB), is also required for this conversion. A homolog of this gene, stcQ, is present in the A. nidulans sterigmatocystin (ST) biosynthesis cluster. Disruption of aflX in Aspergillus flavus gave transformants that accumulated approximately 4-fold more VA and fourfold less aflatoxin than the untransformed strain. Southern and Northern blot analyses confirmed that aflX was the only gene disrupted in these transformants. Feeding ST or O-methylsterigmatocystin, but not VA or earlier precursor metabolites, restored normal levels of AF production. The protein encoded by aflX is predicted to have domains typical of an NADH-dependent oxidoreductase. It has 27% amino acid identity to a protein encoded by the aflatoxin cluster gene, aflO (avfA). Some of domains in the protein are similar to those of epoxide hydrolases.
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Affiliation(s)
- Jeffrey W Cary
- Southern Regional Research Center/ARS/USDA, P.O. Box 19687, New Orleans, LA 70179, USA.
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Aspergillus flavus expressed sequence tags and microarray as tools in understanding aflatoxin biosynthesis. Mycotoxin Res 2006; 22:16-21. [DOI: 10.1007/bf02954552] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Wen Y, Hatabayashi H, Arai H, Kitamoto HK, Yabe K. Function of the cypX and moxY genes in aflatoxin biosynthesis in Aspergillus parasiticus. Appl Environ Microbiol 2005; 71:3192-8. [PMID: 15933021 PMCID: PMC1151844 DOI: 10.1128/aem.71.6.3192-3198.2005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The pathway oxoaverantin (OAVN) --> averufin (AVR) --> hydroxyversicolorone (HVN) --> versiconal hemiacetal acetate (VHA) is involved in aflatoxin biosynthesis, and the cypX and moxY genes, which are present in the aflatoxin gene cluster, have been previously suggested to be involved in this pathway. To clarify the function of these two genes in more detail, we disrupted the genes in aflatoxigenic Aspergillus parasiticus NRRL 2999. The cypX-deleted mutant lost aflatoxin productivity and accumulated AVR in the mycelia. Although this mutant converted HVN, versicolorone (VONE), VHA, and versiconol acetate (VOAc) to aflatoxins in feeding experiments, it could not produce aflatoxins from either OAVN or AVR. The moxY-deleted mutant also lost aflatoxin productivity, whereas it newly accumulated HVN and VONE. In feeding experiments, this mutant converted either VHA or VOAc to aflatoxins but did not convert OAVN, AVR, HVN, or VONE to aflatoxins. These results demonstrated that cypX encodes AVR monooxygenase, catalyzing the reaction from AVR to HVN, and moxY encodes HVN monooxygenase, catalyzing a Baeyer-Villiger reaction from HVN to VHA as well as from VONE to VOAc. In this work, we devised a simple and rapid method to extract DNA from many fungi for PCR analyses in which cell disruption with a shaker and phenol extraction were combined.
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Affiliation(s)
- Ying Wen
- National Food Research Institute, Tsukuba, Ibaraki 305-8642, Japan
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Yang ZY, Shim WB, Kim JH, Park SJ, Kang SJ, Nam BS, Chung DH. Detection of aflatoxin-producing molds in Korean fermented foods and grains by multiplex PCR. J Food Prot 2004; 67:2622-6. [PMID: 15553652 DOI: 10.4315/0362-028x-67.11.2622] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
An assay based on multiplex PCR was applied for the detection of potential aflatoxin-producing molds in Korean fermented foods and grains. Three genes, avfA, omtA, and ver-1, coding for key enzymes in aflatoxin biosynthesis, were used as aflatoxin-detecting target genes in multiplex PCR. DNA extracted from Aspergillus flavus, Aspergillus parasiticus, Aspergillus oryzae, Aspergillus niger, Aspergillus terreus, Penicillium expansum, and Fusarium verticillioides was used as PCR template to test specificity of the multiplex PCR assay. Positive results were achieved only with DNA that was extracted from the aflatoxigenic molds A. flavus and A. parasiticus in all three primer pairs. This result was supported by aflatoxin detection with direct competitive enzyme-linked immunosorbent assay (DC-ELISA). The PCR assay required just a few hours, enabling rapid and simultaneous detection of many samples at a low cost. A total of 22 Meju samples, 24 Doenjang samples, and 10 barley samples commercially obtained in Korea were analyzed. The DC-ELISA assay for aflatoxin detection gave negative results for all samples, whereas the PCR-based method gave positive results for 1 of 22 Meju samples and 2 of 10 barley samples. After incubation of the positive samples with malt extract agar, DC-ELISA also gave positive results for aflatoxin detection. All Doenjang samples were negative by multiplex PCR and DC-ELISA assay, suggesting that aflatoxin contamination and the presence of aflatoxin-producing molds in Doenjang are probably low.
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Affiliation(s)
- Zheng-You Yang
- Division of Applied Life Science of Graduate School, Gyeongsang National University, Chinju 660-701 Korea
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Chang PK, Yabe K, Yu J. The Aspergillus parasiticus estA-encoded esterase converts versiconal hemiacetal acetate to versiconal and versiconol acetate to versiconol in aflatoxin biosynthesis. Appl Environ Microbiol 2004; 70:3593-9. [PMID: 15184162 PMCID: PMC427728 DOI: 10.1128/aem.70.6.3593-3599.2004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In aflatoxin biosynthesis, the pathway for the conversion of 1-hydroxyversicolorone to versiconal hemiacetal acetate (VHA) to versiconal (VHOH) is part of a metabolic grid. In the grid, the steps from VHA to VHOH and from versiconol acetate (VOAc) to versiconol (VOH) may be catalyzed by the same esterase. Several esterase activities are associated with the conversion of VHA to VHOH, but only one esterase gene (estA) is present in the complete aflatoxin gene cluster of Aspergillus parasiticus. We deleted the estA gene from A. parasiticus SRRC 2043, an O-methylsterigmatocystin (OMST)-accumulating strain. The estA-deleted mutants were pigmented and accumulated mainly VHA and versicolorin A (VA). A small amount of VOAc and other downstream aflatoxin intermediates, including VHOH, versicolorin B, and OMST, also were accumulated. In contrast, a VA-accumulating mutant, NIAH-9, accumulated VA exclusively and neither VHA nor VOAc were produced. Addition of the esterase inhibitor dichlorvos (dimethyl 2,2-dichlorovinylphosphate) to the transformation recipient strain RHN1, an estA-deleted mutant, or NIAH-9 resulted in the accumulation of only VHA and VOAc. In in vitro enzyme assays, the levels of the esterase activities catalyzing the conversion of VHA to VHOH in the cell extracts of two estA-deleted mutants were decreased to approximately 10% of that seen with RHN1. Similar decreases in the esterase activities catalyzing the conversion of VOAc to VOH were also obtained. Thus, the estA-encoded esterase catalyzes the conversion of both VHA to VHOH and VOAc to VOH during aflatoxin biosynthesis.
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Affiliation(s)
- Perng-Kuang Chang
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, LA 70124, USA.
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42
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Yu J, Chang PK, Ehrlich KC, Cary JW, Bhatnagar D, Cleveland TE, Payne GA, Linz JE, Woloshuk CP, Bennett JW. Clustered pathway genes in aflatoxin biosynthesis. Appl Environ Microbiol 2004; 70:1253-62. [PMID: 15006741 PMCID: PMC368384 DOI: 10.1128/aem.70.3.1253-1262.2004] [Citation(s) in RCA: 553] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Jiujiang Yu
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, Louisiana 70124, USA.
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Chang PK. Lack of interaction between AFLR and AFLJ contributes to nonaflatoxigenicity of Aspergillus sojae. J Biotechnol 2004; 107:245-53. [PMID: 14736460 DOI: 10.1016/j.jbiotec.2003.10.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Aspergillus sojae, which is believed to be a domesticated strain of Aspergillus parasiticus, contains all of the aflatoxin biosynthetic genes but is unable to produce aflatoxins and is generally recognized as safe (GRAS) for producing fermented foods. In A. parasiticus both aflR, the aflatoxin pathway-specific regulatory gene, and aflJ, a co-activator gene, are necessary for transcription of genes encoding the aflatoxin biosynthetic enzymes. A. sojae aflR differs from A. parasiticus aflR in that it encodes extra His and Ala, and has a pretermination defect that causes truncation of the carboxyl terminus of the predicted protein. A. sojae aflJ differs from A. parasiticus aflJ in that it encodes a predicted protein with Ser39 replaced by Ala and Ser283 replaced by Pro. Steady-state levels of aflatoxin biosynthetic gene transcripts of aflR, aflJ, pksA, nor1, ver1 and omtA in A. sojae as determined by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) were much lower than those of A. parasiticus. Yeast two-hybrid assays showed that the truncated A. sojae AFLR did not interact with AFLJ of A. sojae and A. parasiticus but that an A. sojae AFLR reverted to the putative ancestral form interacted normally with AFLJ of A. sojae and A. parasiticus. Deletion analysis showed that both amino- and carboxy-terminal regions of the A. sojae AFLJ were important for the R-J interaction. The truncated A. sojae AFLR thus not only was impaired in its ability to activate transcription of aflatoxin biosynthetic genes, but also was unable to interact with AFLJ, in A. parasiticus both of which are required for normal expression of the aflatoxin biosynthetic genes. Consequently, the lack of aflatoxin-producing ability of A. sojae resulted primarily from two defects in the regulatory mechanism responsible for gene transcription.
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Affiliation(s)
- Perng-Kuang Chang
- Southern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124, USA.
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44
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Genomics of Economically Significant Aspergillus and Fusarium Species. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/s1874-5334(04)80013-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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45
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Yu J, Mohawed SM, Bhatnagar D, Cleveland TE. Substrate-induced lipase gene expression and aflatoxin production in Aspergillus parasiticus and Aspergillus flavus. J Appl Microbiol 2003; 95:1334-42. [PMID: 14633008 DOI: 10.1046/j.1365-2672.2003.02096.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To establish a relationship between lipase gene expression and aflatoxin production by cloning the lipA gene and studying its expression pattern in several aflatoxigenic and nontoxigenic isolates of Aspergillus flavus and A. parasiticus. METHODS AND RESULTS We have cloned a gene, lipA, that encodes a lipase involved in the breakdown of lipids from aflatoxin-producing A. flavus, A. parasiticus and two nonaflatoxigenic A. flavus isolates, wool-1 and wool-2. The lipA gene was transcribed under diverse media conditions, however, no mature mRNA was detected unless the growth medium was supplemented with 0.5% soya bean or peanut oil or the fungus was grown in lipid-rich medium such as coconut medium. The expression of the lipase gene (mature mRNA) under substrate-induced conditions correlated well with aflatoxin production in aflatoxigenic species A. flavus (SRRC 1007) and A. parasiticus (SRRC 143). CONCLUSIONS Substrate-induced lipase gene expression might be indirectly related to aflatoxin formation by providing the basic building block 'acetate' for aflatoxin synthesis. No direct relationship between lipid metabolism and aflatoxin production can be ascertained, however, lipase gene expression correlates well with aflatoxin formation. SIGNIFICANCE AND IMPACT OF THE STUDY Lipid substrate induces and promotes aflatoxin formation. It gives insight into genetic and biochemical aspects of aflatoxin formation.
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Affiliation(s)
- J Yu
- USDA/ARS, Southern Regional Research Center, New Orleans, LA, USA.
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46
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Brown RL, Brown-Jenco CS, Bhatnagar D, Payne GA. Construction and preliminary evaluation of an Aspergillus flavus reporter gene construct as a potential tool for screening aflatoxin resistance. J Food Prot 2003; 66:1927-31. [PMID: 14572235 DOI: 10.4315/0362-028x-66.10.1927] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Effective preharvest strategies to eliminate aflatoxin accumulation in crops are not presently available. The molecular biology of aflatoxin biosynthesis has been extensively studied, and genetic and molecular tools such as reporter gene systems for the measurement of fungal growth have been developed. A reporter construct containing the Aspergillus flavus beta-tubulin gene promoter fused to Escherichia coli beta-glucuronidase (GUS) has been shown to be a reliable tool for the indirect measurement of fungal growth in maize kernels. Since cost-saving alternative methods for the direct measurement of aflatoxin levels are needed to facilitate more widespread field and laboratory screening of maize lines, a new reporter gene construct involving the promoter region of the omtA gene of the aflatoxin biosynthetic pathway was constructed and tested. Expression of GUS activity by this construct (omtA::GUS) was correlated with aflatoxin accumulation in culture. In the fungal transformant GAP26-1, which harbors this construct, aflatoxin production and GUS expression on sucrose-containing medium showed the same temporal pattern of toxin induction. Furthermore, GUS expression by GAP26-1 was shown to be associated with aflatoxin accumulation in maize kernels inoculated with this strain. Our results suggest that this and other reporter gene pathway promoter constructs may provide superior alternatives to direct aflatoxin quantification with respect to time, labor, and materials for the screening of maize lines for resistance to aflatoxin accumulation.
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Affiliation(s)
- Robert L Brown
- Southern Regional Research Center, USDA Agricultural Research Service, New Orleans, Louisiana 70179, USA
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Cuero R, Ouellet T, Yu J, Mogongwa N. Metal ion enhancement of fungal growth, gene expression and aflatoxin synthesis in Aspergillus flavus: RT-PCR characterization. J Appl Microbiol 2003; 94:953-61. [PMID: 12752802 DOI: 10.1046/j.1365-2672.2003.01870.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To determine the effect of mineral ions (e.g., Zn2+, Cu2+, and Fe2+) on the enhancement of fungal growth, total RNA, aflatoxin pathway gene expression, and production of aflatoxin and its precursor O-methylsterigmatocystin (OMST). METHODS AND RESULTS The influence of the metal ions, as a single or mixed treatments, was observed in submerged cultures of toxigenic Aspergillus flavus through changes in the fungal RNA or aflatoxin pathway gene (omtA) by reverse transcription-polymerase chain reaction (RT-PCR) levels, and also in fungal dry-weight accumulation, aflatoxin and OMST production. CONCLUSIONS The ion treatments induced changes of fungal total RNA, mRNA levels, associate fungal growth, biosynthesis of aflatoxin and OMST, and enhanced expression of RT-PCR. SIGNIFICANCE AND IMPACT OF STUDY Demonstrates at the cellular and molecular level, the significant effects of metal ions on both fungal growth and production of aflatoxin.
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Affiliation(s)
- R Cuero
- Prairie View A & M University, CARC, PO BOX 685, Prairie View, TX 77446, USA.
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Abstract
Mycotoxins are secondary metabolites produced by microfungi that are capable of causing disease and death in humans and other animals. Because of their pharmacological activity, some mycotoxins or mycotoxin derivatives have found use as antibiotics, growth promotants, and other kinds of drugs; still others have been implicated as chemical warfare agents. This review focuses on the most important ones associated with human and veterinary diseases, including aflatoxin, citrinin, ergot akaloids, fumonisins, ochratoxin A, patulin, trichothecenes, and zearalenone.
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Affiliation(s)
- J W Bennett
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118, USA.
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Yabe K, Chihaya N, Hamamatsu S, Sakuno E, Hamasaki T, Nakajima H, Bennett JW. Enzymatic conversion of averufin to hydroxyversicolorone and elucidation of a novel metabolic grid involved in aflatoxin biosynthesis. Appl Environ Microbiol 2003; 69:66-73. [PMID: 12513978 PMCID: PMC152417 DOI: 10.1128/aem.69.1.66-73.2003] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pathway from averufin (AVR) to versiconal hemiacetal acetate (VHA) in aflatoxin biosynthesis was investigated by using cell-free enzyme systems prepared from Aspergillus parasiticus. When (1'S,5'S)-AVR was incubated with a cell extract of this fungus in the presence of NADPH, versicolorin A and versicolorin B (VB), as well as other aflatoxin pathway intermediates, were formed. When the same substrate was incubated with the microsome fraction and NADPH, hydroxyversicolorone (HVN) and VHA were formed. However, (1'R,5'R)-AVR did not serve as the substrate. In cell-free experiments performed with the cytosol fraction and NADPH, VHA, versicolorone (VONE), and versiconol acetate (VOAc) were transiently produced from HVN in the early phase, and then VB and versiconol (VOH) accumulated later. Addition of dichlorvos (dimethyl 2,2-dichlorovinylphosphate) to the same reaction mixture caused transient formation of VHA and VONE, followed by accumulation of VOAc, but neither VB nor VOH was formed. When VONE was incubated with the cytosol fraction in the presence of NADPH, VOAc and VOH were newly formed, whereas the conversion of VOAc to VOH was inhibited by dichlorvos. The purified VHA reductase, which was previously reported to catalyze the reaction from VHA to VOAc, also catalyzed conversion of HVN to VONE. Separate feeding experiments performed with A. parasiticus NIAH-26 along with HVN, VONE, and versicolorol (VOROL) demonstrated that each of these substances could serve as a precursor of aflatoxins. Remarkably, we found that VONE and VOROL had ring-opened structures. Their molecular masses were 386 and 388 Da, respectively, which were 18 Da greater than the molecular masses previously reported. These data demonstrated that two kinds of reactions are involved in the pathway from AVR to VHA in aflatoxin biosynthesis: (i) a reaction from (1'S,5'S)-AVR to HVN, catalyzed by the microsomal enzyme, and (ii) a new metabolic grid, catalyzed by a new cytosol monooxygenase enzyme and the previously reported VHA reductase enzyme, composed of HVN, VONE, VOAc, and VHA. A novel hydrogenation-dehydrogenation reaction between VONE and VOROL was also discovered.
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Affiliation(s)
- Kimiko Yabe
- National Food Research Institute, Tsukuba, Ibaraki 305-8642, Japan.
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Munkvold GP. Cultural and genetic approaches to managing mycotoxins in maize. ANNUAL REVIEW OF PHYTOPATHOLOGY 2003; 41:99-116. [PMID: 12730397 DOI: 10.1146/annurev.phyto.41.052002.095510] [Citation(s) in RCA: 207] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Infection of maize kernels by toxigenic fungi remains a challenging problem despite decades of research progress. Cultural practices, including crop rotation, tillage, planting date, and management of irrigation and fertilization, have limited effects on infection and subsequent mycotoxin accumulation. Current infrastructure and grain storage practices in developed countries can prevent postharvest development of mycotoxins, but this aspect remains a threat in developing countries, especially in tropical areas. Because most mycotoxin problems develop in the field, strategies are needed to prevent infection of growing plants by toxigenic fungi. Developing genetic resistance to Aspergillus flavus, Gibberella zeae, and Fusarium spp. (particularly F. verticillioides) in maize is a high priority. Sources of resistance to each of these pathogens have been identified and have been incorporated into public and private breeding programs. However, few, if any, commercial cultivars have adequate levels of resistance. Efforts to control infection or mycotoxin development through conventional breeding and genetic engineering are reviewed. The role of transgenic insect control in the prevention of mycotoxins in maize is discussed.
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Affiliation(s)
- Gary P Munkvold
- Pioneer Hi-Bred International, 7301 NW 62 Avenue, PO Box 85, Johnston, Iowa 50131-0085, USA.
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