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1.
Fungal contamination of agricultural commodities, particularly by mycotoxigenic fungi, represents an enormous concern for global food security in terms of feeding the world's growing population with sufficient and safe food. Not only do they reduce crop yield and quality, but they also produce substantial numbers of mycotoxins, which pose serious adverse health effects in human and animals. As the genome of most mycotoxigenic species have been sequenced, the gene clusters involved in the biosynthesis of agriculturally important mycotoxins including aflatoxins, fumonisins, ochratoxins, zearalenone and trichothecenes, have been largely identified and characterised, with their roles elucidated by researchers. This review provides a comprehensive overview of the current knowledge of genes involved in the biosynthetic pathways of mycotoxins. In addition, the influence of climatic factors including water, temperature and carbon dioxide on differential mycotoxin gene expressions have been highlighted. Overall, the relationship between the relative expression of key regulatory and structural genes under different environmental conditions is significantly correlated with mycotoxins production. This indicates that mycotoxin gene induction can be used as a reliable indicator or marker to monitor mycotoxin production pre-and-post harvest. Furthermore, current strategies to manage mycotoxin risks still require improvement. Thus, an accurate understanding of the molecular mechanisms of mycotoxin biosynthesis in mycotoxigenic species could help to develop an innovative, robust targeted control strategy. This could include the exploitation of novel compounds, which can inhibit biosynthetic genes, to minimise mycotoxin risks.  相似文献   

2.
吴荣  王栋  徐岩  李鸣 《微生物学通报》2013,40(8):1437-1447
【目的】在对中国传统优势浓香型白酒产业中重要功能微生物华根霉菌株CCTCCM201021全基因组测序的基础上,以生物信息学的方法和手段主要针对真菌毒素的合成代谢途径及关键基因进行分析,考察微生物在食品工业应用中的安全性。【方法】应用Illumina平台Solexa测序技术对华根霉进行基因组测序,运用SOAPdenovo组装软件进行拼接,并进行一系列生物信息分析,考察根霉素、小孢根霉素及典型丝状真菌毒素代谢的主要途径及相关基因,包括PKS、NRPS与PKS-NRPS混合代谢途径;萜类化合物代谢和其他代谢途径等,判断华根霉是否具有产真菌毒素的潜在危害性。【结果】测序结果表明华根霉全基因组大小为45.70 Mb左右,GC含量为36.99%。通过基因预测软件分析得到基因17 676个,共注释基因13 243个。通过进化树与同源基因比较分析,与目前基因组测序完成的仅有的3株接合菌基因组相比,序列相似性普遍偏低,与华根霉存在较为显著的差异,但同源基因的相似性在60%左右。代谢分析表明,华根霉中仅存在较少聚酮合成、萜类化合物合成途径代谢基因,存在大量异源物质降解途径基因。【结论】华根霉基本不具备产目前已知的真菌毒素的关键基因或合成能力,可以认为其发酵产品是相对安全的。在酿造过程中,不仅可作为糖化菌,在混菌发酵时,对部分具有抑菌能力的抗生物质具有降解功能,是发酵工业中应用的相对安全的重要生产菌。  相似文献   

3.
植物多胺代谢途径研究进展   总被引:6,自引:0,他引:6  
多胺是一类小分子生物活性物质,广泛存在于生物体内,与植物的生长发育、衰老及抗逆性都有着密切的联系。目前,在植物中的多胺合成途径已经基本揭示,其生理作用在分子水平上逐步得到阐明。对多胺合成突变体和各种转基因植物的研究也使得人们更深入地了解了多胺以及其合成代谢相关酶在植物生长发育等生理过程中的重要作用。以下概述了植物多胺代谢途径,重点综述了代谢途径中各基因的功能及遗传操作的最新进展,并对将来的研究方向尤其是相关基因在植物抗逆境 (包括生物和非生物逆境) 基因工程方面的应用作了讨论。  相似文献   

4.
Bradshaw RE  Zhang S 《Mycopathologia》2006,162(3):201-213
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.  相似文献   

5.
The understanding of the complexities and molecular events regulating genes and the activators involved in terpenoid indole alkaloid (TIA) metabolism is known to a certain extent in cell cultures of an important TIA yielding plant, Catharanthus roseus, though it is not yet complete. Recently, the repressors of early TIA pathway genes have also been identified. However, their roles in the regulation of TIA pathway in C. roseus cell cultures remains yet unknown. We have made a comparative profiling of genes catalyzing the important steps of 2-C methyl-D-erythritol-4-phosphate (MEP), shikimate and TIA biosynthetic pathways, their activator and repressors using macroarray, semiquantitative RT-PCR and northern analyses in a rotation culture system of C. roseus comprising differentiated and proliferated cells. Our results demonstrate that TIA biosynthetic pathway genes and their activators show variable expression pattern, which was correlated with the changes in the cellular conditions in these systems. Under similar conditions, TIA pathway repressors show strong and consistent expression. The role of repressors in the complex regulation of the TIA pathway in C. roseus cell cultures is discussed. The results were supported by HPLC data, which demonstrated that the molecular program of cellular differentiation is intimately linked with TIA pathway gene expression and TIA production in C. roseus cell cultures.  相似文献   

6.
7.
Biosynthesis of deoxyaminosugars in antibiotic-producing bacteria   总被引:3,自引:0,他引:3  
Deoxyaminosugars comprise an important class of deoxysugars synthesized by a variety of different microorganisms; they can be structural components of lipopolysaccharides, extracellular polysaccharides, and secondary metabolites such as antibiotics. Genes involved in the biosynthesis of the deoxyaminosugars are often clustered and are located in the vicinity of other genes required for the synthesis of the final compound. Most of the gene clusters for aminosugar biosynthesis have common features, as they contain genes encoding dehydratases, isomerases, aminotransferases, methyltransferases, and glycosyltransferases. In the present mini-review, the proposed biosynthetic pathways for deoxyaminosugar components of both macrolide and non-macrolide antibiotics are highlighted. The possibilities for genetic manipulations of the deoxyaminosugar biosynthetic pathways aimed at production of novel secondary metabolites are discussed.  相似文献   

8.
The sequencing of Aspergillus genomes has revealed that the products of a large number of secondary metabolism pathways have not yet been identified. This is probably because many secondary metabolite gene clusters are not expressed under normal laboratory culture conditions. It is, therefore, important to discover conditions or regulatory factors that can induce the expression of these genes. We report that the deletion of sumO, the gene that encodes the small ubiquitin-like protein SUMO in A. nidulans, caused a dramatic increase in the production of the secondary metabolite asperthecin and a decrease in the synthesis of austinol/dehydroaustinol and sterigmatocystin. The overproduction of asperthecin in the sumO deletion mutant has allowed us, through a series of targeted deletions, to identify the genes required for asperthecin synthesis. The asperthecin biosynthesis genes are clustered and include genes encoding an iterative type I polyketide synthase, a hydrolase, and a monooxygenase. The identification of these genes allows us to propose a biosynthetic pathway for asperthecin.  相似文献   

9.
Fungal polyketides comprise a diverse group of secondary metabolites that play an important role for drug discovery, as pigments, and as mycotoxins. Their biosynthesis is governed by multidomain enzymes, so-called fungal type I polyketide synthases (PKS). Investigating the molecular basis of polyketide biosynthesis in fungi is of great importance for ecological and pharmacological reasons. In addition, cloning, functional analysis and expression of fungal PKS genes also set the basis for engineering the yet largely untapped biosynthetic potential.  相似文献   

10.
Dampness in buildings has been linked to adverse health effects, but the specific causative agents are unknown. Mycotoxins are secondary metabolites produced by molds and toxic to higher vertebrates. In this study, mass spectrometry was used to demonstrate the presence of mycotoxins predominantly produced by Aspergillus spp. and Stachybotrys spp. in buildings with either ongoing dampness or a history of water damage. Verrucarol and trichodermol, hydrolysis products of macrocyclic trichothecenes (including satratoxins), and trichodermin, predominately produced by Stachybotrys chartarum, were analyzed by gas chromatography-tandem mass spectrometry, whereas sterigmatocystin (mainly produced by Aspergillus versicolor), satratoxin G, and satratoxin H were analyzed by high-performance liquid chromatography-tandem mass spectrometry. These mycotoxin analytes were demonstrated in 45 of 62 building material samples studied, in three of eight settled dust samples, and in five of eight cultures of airborne dust samples. This is the first report on the use of tandem mass spectrometry for demonstrating mycotoxins in dust settled on surfaces above floor level in damp buildings. The direct detection of the highly toxic sterigmatocystin and macrocyclic trichothecene mycotoxins in indoor environments is important due to their potential health impacts.  相似文献   

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