云南大叶种晒青毛茶提取物对产毒黄曲霉生长及产毒的影响

普洱茶在发酵过程中,微生物组成十分复杂,尤其是黑曲霉等霉菌起到主要作用,因此一些消费者担心普洱茶在发酵过程中受到黄曲霉毒素(AFS)的污染。本文通过测定菌落直径、孢子萌发及菌丝体干重等方法研究云南大叶种茶提取物对产毒黄曲霉AS3.4408生长的影响;采用紫外荧光法和HPLC法研究云南大叶种茶提取物对产毒黄曲霉AFS生物合成的影响;并将产毒黄曲霉AS3.4408接种到云南大叶种茶叶中,检测茶叶中的AFS含量,以求对普洱茶的安全性进行评估。研究表明,云南大叶种茶提取物对产毒黄曲霉AS3.4408菌落的生长及产毒均具有显著的抑制作用,且存在明显的剂量依赖关系;将产毒黄曲霉AS3.4408接种到云南大叶种茶叶中,菌株生长良好,但茶叶基质经HPLC检测,未检测到黄曲霉毒素B1、B2、G1和G2,表明云南大叶种茶中的某种(些)成分对黄曲霉毒素的生物合成具有抑制作用。     

微生物对黄曲霉毒素的抑制机制研究进展

部分黄曲霉菌会对农作物及产品造成严重污染.受相关基因的影响,黄曲霉会产生一种对人类健康与畜禽养殖构成重大威胁的真菌毒素,即黄曲霉毒素,在田间、储藏期或运输过程中黄曲霉毒素污染均可能发生.防止黄曲霉毒素进入食物链的策略有很多,其中采用生物法防治黄曲霉污染越来越引起研究者的重视,也逐渐被人们所接受.利用微生物对黄曲霉及毒素...     

粮油作物中黄曲霉毒素风险预测预警研究进展

粮油作物中黄曲霉毒素污染严重影响着人和动物的健康。开展粮油作物中黄曲霉毒素产生关键影响因素研究,构建早期风险预测模型,是减少污染发生、保障人类健康和减少经济损失的重要途径。本文在总结黄曲霉毒素在粮油作物中风险发生的影响因素的基础上,从黄曲霉毒素易发多发的环节如作物收获期和储藏期讨论了预测模型建的研究进展,同时归纳了目前预测模型主要建立方法,包括基于回归、神经网络等方法建立的数据驱动模型和基于黄曲霉毒素产生机制建立的机理模型。通过分析目前的研究,讨论了未来粮油作物中黄曲霉毒素风险预测模型的研究方向和应用场景,为开展我国作物中黄曲霉毒素污染风险早期预测和污染防控研究提供依据。     

黄曲霉毒素的产生机制及污染防控策略

黄曲霉是一种广泛分布的环境习居菌,经常在种植、贮藏、加工、运输过程污染玉米、花生等富含脂肪酸的粮食及相关食品和饲料,并会产生多种有毒次生代谢产物。其中,黄曲霉毒素是黄曲霉产生的最主要真菌毒素之一,是公认的一类致癌物。黄曲霉毒素污染严重影响农产品质量安全;带来巨大的经济损失和贸易争端;更重要的是,黄曲霉毒素具有高毒性、高致癌性、致突变性和免疫抑制性,严重威胁人畜健康。因此,黄曲霉毒素合成、调控及防控的相关工作一直是食品安全领域的研究重点和热点。阐述已知的黄曲霉毒素产生途径及相关调控机制,并介绍了多种有效的防控手段。重点讨论光照、温度、水活度、营养物质、pH值、氧化胁迫等环境因子对黄曲霉毒素合成的影响及已明确的调控机制;阐明了参与不同环境因子调控毒素合成的关键转录因子;同时分别从物理、化学和生物等不同技术层面介绍了多种有效抑制或降解黄曲霉毒素的方法,总结了黄曲霉毒素污染防控策略;并对今后的关键研究方向和重点防控措施做出了展望。     

浅谈出口葵花籽仁黄曲霉毒素污染风险关键控制点的探讨

近年来, 天津口岸出口葵花籽仁的业务发展较快, 年出口在3万吨左右, 货值达8000万美元以上, 产品主要销往欧盟、日本市场, 用于食品配料和宠物饲料。其中三道眉、大黑片、西北油葵等籽仁品种在国际市场具有较高声誉。但值得重视的是, 黄曲霉毒素问题近年来屡遭欧盟等进口国家的特别检查和预警通报, 甚至出现退运。2008年以来, 天津检验检疫部门多次在出口货物检测中发现黄曲霉毒素超标, 不合格率逐年上升。如何通过加强对种植、生产、加工环节的监督管理来降低黄曲霉毒素对葵花籽仁的污染风险, 是我们当前所面临的重要课题。本文利用HACCP原理, 对出口葵花籽仁黄曲霉毒素污染的各控制环节进行分析, 通过加强对关键控制点的控制和管理, 达到减少黄曲霉毒素对葵花籽仁产品污染的目的。     

花生黄曲霉毒素污染拮抗菌B25-5的筛选、鉴定及控制效果

黄曲霉毒素是花生中重要的污染物,对人畜的健康具有极强的危害性。本研究筛选对黄曲霉毒素污染具有较强抑制作用的有益微生物,为花生中黄曲霉毒素污染治理提供支持。本研究从河北省滦南县、滦县、玉田、丰南等主产区县的花生中分离有益微生物,通过室内外实验,获得对产毒黄曲霉较强拮抗菌株B25-5。经分子生物学及理化性鉴定,该菌株为解淀粉芽孢杆菌。进一步开展了B25-5对黄曲霉孢子萌发的抑制作用、黄曲霉毒素的消减作用及黄曲霉毒素的分解作用等几个方面的研究,结果表明,拮抗菌可以显著的抑制产毒黄曲霉孢子的萌发、生长、菌丝的生长,降低黄曲霉毒素的产生及消除黄曲霉毒素。     

茶叶中黄曲霉毒素的安全性风险研究进展

茶叶是世界上最流行的饮品之一,因其独特的风味和对人体有益的健康功能为人们所喜爱。茶叶在生长、采摘、加工、运输及储存过程中可能存在潜在的黄曲霉毒素污染,黄曲霉毒素是世界上已知毒性最大的真菌毒素,对人类健康存在极大威胁。黄曲霉毒素主要有四种常见的亚型,包括黄曲霉毒素B1,B2,G1,G2。其中黄曲霉毒素B1是毒性最大的黄曲霉毒素,被国际癌症研究机构列为Ⅰ类致癌物。因此评估茶叶中是否存在黄曲霉毒素及其安全性具有重要意义。本文系统地综述了黄曲霉毒素的理化性质、致病机理,以及茶叶中可能产黄曲霉毒素的微生物和黄曲霉毒素在茶叶中的检出情况等,并探讨茶叶中黄曲霉毒素的潜在风险,为茶叶中黄曲霉毒素的风险评估与防控提供支持。     

乳酸菌对乳制品中黄曲霉毒素的生物防治作用

黄曲霉及其毒素污染常发生于乳制品中,导致一定的经济损失,且严重危害人体健康。乳酸菌及其代谢产物均可有效地吸附去除黄曲霉毒素。就黄曲霉毒素、乳酸菌生物防治作用、乳酸菌对乳制品中黄曲霉毒素生物防治作用的应用及安全性评价进行综述,为提高我国发酵乳制品的卫生安全质量提供理论依据。     

植物挥发油对黄曲霉毒素产生菌及其毒素合成的影响

黄曲霉毒素(AFT)是由黄曲霉(Aspergillus flavus)和寄生曲霉(Aspergillus parasiticus)等曲霉属真菌产生的次生代谢产物,具有致畸、致癌、致突变等作用.AFT污染多种粮食作物及食品,其极强的毒性严重威胁到人体健康.寻找各种黄曲霉毒素抑制剂已成为国内外研究的热点.部分抗生素类药物及化学杀菌剂虽然具有较强的抗黄曲霉作用,但鉴于其毒副作用较明显,使用范围非常有限.近二十年来,人们开始从天然产物中寻找毒副作用低、易降解并且安全性高的黄曲霉抑制剂.本文对天然植物挥发油及其单体成分抑制黄曲霉和寄生曲霉生长并抑制AFT合成,以及在粮食、食品及其包装等方面的应用情况进行综述,为进一步研究植物挥发油类成分的抑菌机制和产品开发提供参考.     

部分国家母乳中黄曲霉毒素M_1的污染状况

为了解母乳中黄曲霉毒素M1的污染状况,并为控制我国母乳中黄曲霉毒素M1的污染和降低对婴幼儿的危害提供借鉴和依据,本文从研究对象及采样、污染状况、对健康的影响等方面进行了综述。     

非脱羧勒克菌wt16对黄曲霉菌生长与产毒的抑制作用

黄曲霉菌及其毒素严重威胁农产品质量安全,本文旨在探寻非脱羧勒克菌对黄曲霉菌及其毒素污染防控效果。从湖北黄陂分离筛选出一株非脱梭勒克菌wt16,将其与黄曲霉菌在液体培养基中共培养后测定非脱羧勒克菌wt16菌株对黄曲霉菌生长及产毒的抑制率。结果表明,在沙氏液体培养基中,非脱羧勒克菌wt16能明显抑制黄曲霉菌的生长及产毒,对其菌丝生长的抑制率为77%~92%,对其产毒的抑制率为90%~96%。通过扫描电子显微镜观察发现,非脱羧勒克菌wt16能改变黄曲霉菌丝的形态,使得黄曲霉菌丝体由规则的球体聚集成不规则形状,单个菌丝会由细长型断裂成小截形态,菌丝表面也变得更为光滑;并且发现wt16在花生粉及未受机械损伤的花生颗粒上对黄曲霉菌的生长及产毒均表现出很强的抑制作用。进一步研究发现,非脱羧勒克菌wt16菌株发酵上清液中含有能抑制黄曲霉毒素合成的有效成分,且该发酵上清液的制备以培养4 d以上为最佳,培养温度为15~40 ℃。     

黄曲霉群体感应研究进展

曲霉属真菌(Aspergillus)如黄曲霉、寄生曲霉侵染玉米、花生等富含油脂的作物种子后产生的黄曲霉毒素(aflatoxin)具有强致癌作用,严重威胁食品安全和人类健康。群体感应(quorum sensing,QS)曾经认为只存在于细菌中,但是在真菌中也存在QS系统,菌体的形态建成和次级代谢产物的产生都与细胞的群体密度有关。黄曲霉拥有类似群体感应的机制,菌核到分生孢子的转换受细胞密度和脂肪氧合酶调控。氧脂素作为信号分子通过密度依赖机制可抑制或促进黄曲霉的生长及黄曲霉毒素的生物合成,本文综述了黄曲霉群体感应及信号通路的研究进展,旨在从群体感应的角度抑制黄曲霉毒素的产生,为微生物与食品安全的研究提供指导。     

脂氧合酶与作物黄曲霉毒素污染抗性关系研究进展

曲霉属真菌（Aspergillus）侵染玉米、花生等富含油脂的作物种子后产生的黄曲霉毒素（aflatoxin）具有强致癌作用,严重威胁食品安全和人类健康。脂氧合酶（LOX）及其代谢衍生物在曲霉菌一种子互作中具有重要调节作用。LOX活性的增加可提高植物对细菌、真菌和病毒等病原物的抵抗力,同时由于其催化不饱和脂肪酸代谢生成的脂氧合物如茉莉酸甲酯以及挥发性醛类等物质,可影响黄曲霉菌的生长及黄曲霉毒素的生物合成,因而LOX在作物黄曲霉毒素污染抗性遗传改良中具有潜在的利用价值。本文评述了脂氧合酶及其代谢产物与黄曲霉毒素污染抗性关系的研究进展,旨在从植物一病原菌互作的角度揭示作物黄曲霉毒素污染抗性机制,为下一步的研究提供指导。     

植物精油对黄曲霉的抑制机理及应用方式研究进展

黄曲霉是一种常见的真菌,其产生的黄曲霉毒素会对人和动物的生命健康造成威胁,近年来黄曲霉毒素中毒事件频繁发生。植物精油作为一种天然的活性物质,对黄曲霉有较强的抑制作用,其抑菌机理和应用方式依旧受到各国科研工作者广泛关注。本文主要概述了黄曲霉的危害,植物精油对黄曲霉的抑制效果及作用机理,总结了近几年植物精油抑制黄曲霉的应用方式,以期为植物精油在抑制黄曲霉中的合理应用提供理论依据。     

黑曲霉抗产毒黄曲霉作用的初步研究

采用90 × 2.6 × 1013N+/cm2 注入黑曲霉筛选能抗黄曲霉(Aflavus)生长的突变菌株,以利发酵中控制被黄曲霉污染的原材料的再污染。进行产毒黄曲霉与被离子注入的黑曲霉混合对峙、原黑曲霉菌株与黄曲霉单独培养生长及混合对峙培养实验。结果显示经离子注入的菌株及未注入菌株均对黄曲霉产生抑制作用,但后者仅有微弱抑制,前者不仅表现出几乎不能使黄曲霉生长,且已长出的黄曲霉菌丝体较瘦小,并呈灰白色。从培养基中提取物检验结果显示,黄曲霉组表现出有较明显的荧光反应,而黑曲霉菌株对峙培养物提取物中有微弱的荧光反应,其黑曲霉突变株对峙培养物未见荧光反应检出。这表明黑曲霉原菌株虽然能对黄曲霉只有微弱抑制,但表现出黄曲霉产毒和合成色素能力下降。与对照组相比,突变株有较强抑制黄曲霉生长能力。     

Aflatoxin reduction in corn through field application of competitive fungi.

Soil in corn plots was inoculated with nonaflatoxigenic strains of Aspergillus flavus and A. parasiticus during crop years 1994 to 1997 to determine the effect of application of the nontoxigenic strains on preharvest aflatoxin contamination of corn. Corn plots in a separate part of the field were not inoculated and served as controls. Inoculation resulted in significant increases in the total A. flavus/parasiticus soil population in treated plots, and that population was dominated by the applied strain of A. parasiticus (NRRL 21369). In the years when weather conditions favored aflatoxin contamination (1996 and 1997), corn was predominately colonized by A. flavus as opposed to A. parasiticus. In 1996, colonization by wild-type A. flavus was significantly reduced in treated plots compared with control plots, but total A. flavus/parasiticus colonization was not different between the two groups. A change to a more aggressive strain of A. flavus (NRRL 21882) as part of the biocontrol inoculum in 1997 resulted in a significantly (P < 0.001) higher colonization of corn by the applied strain. Weather conditions did not favor aflatoxin contamination in 1994 and 1995. In 1996, the aflatoxin concentration in corn from treated plots averaged 24.0 ppb, a reduction of 87% compared with the aflatoxin in control plots that averaged 188.4 ppb. In 1997, aflatoxin was reduced by 66% in treated corn (29.8 ppb) compared with control corn (87.5 ppb). Together, the data indicated that although the applied strain of A. parasiticus dominated in the soil, the nonaflatoxigenic strains of A. flavus were more responsible for the observed reductions in aflatoxin contamination. Inclusion of a nonaflatoxigenic strain of A. parasiticus in a biological control formulation for aflatoxin contamination may not be as important for airborne crops, such as corn, as for soilborne crops, such as peanuts.     

Comparison of Aspergillus ear rot and aflatoxin contamination in grain of high-oil and normal-oil corn hybrids

High-oil corn (Zea mays L.) grain is a valuable component of feed for monogastric livestock. One method of increasing the concentration of oil in corn grain is the TopCross method. With TopCross, ears of a cytoplasmic male-sterile, normal-oil hybrid are pollinated by a male-fertile, high-oil synthetic hybrid. The concentration of oil in the resulting grain is increased because of xenia effects. Kernels of high-oil corn typically have a larger germ and a smaller endosperm than kernels of comparable normal hybrids. The growth of Aspergillus flavus Link:Fr within germ tissue has been reported to be more extensive than that on the whole corn kernel; therefore, the severity of Aspergillus ear rot could be more extensive and aflatoxin concentrations could be higher in high-oil grain produced by TopCross than in grain with a lower concentration of oil. The objective of this study was to compare Aspergillus ear rot severity levels and aflatoxin concentrations in the grains of hybrids crossed with high-oil or normal-oil pollinators. Fifteen hybrids were evaluated in 1998 and 1999 in Urbana, Ill. Primary ears were inoculated with A. flavus and evaluated for susceptibility to Aspergillus ear rot and aflatoxin production in grain. Concentrations of aflatoxin and oil in corn kernels were significantly higher for high-oil hybrids than for normal-oil hybrids; however, ear rot severity was unaffected by the type of pollinator. These results suggest that grain from high-oil hybrids is at greater risk for aflatoxin contamination during some growing seasons.     

Correlation of growth and aflatoxin production by Aspergillus flavus with some essential metals in gamma irradiated crushed corn

The effects of gamma irradiation and some essential metals on growth and aflatoxin B1 production by Aspergillus flavus in crushed corn were investigated. The production of aflatoxin by A. flavus was influenced by the addition of zinc, copper or iron and the effect gradually decreased with increasing metal concentration from 0 to 300 ppm. A. flavus grew and depleted zinc, copper and iron at initial concentration of 100, 200 or 300 ppm. Presence of 100 ppm zinc, copper or iron plus gamma irradiation (0.5, 1.0, 2.0 kGy) enhanced the growth of A. flavus and the production of aflatoxin in contrast with irradiated samples alone. A. flavus was able to metabolize and deplete elements in all gamma-irradiated samples. These results suggest that stricter control of element levels in gamma irradiated grains could control aflatoxin contamination.     

Aflatoxin-producing Aspergillus species from Thailand

Aflatoxin-producing Aspergillus species were isolated from soil samples from ten different regions within Thailand. Aspergillus flavus was present in all of the soil samples. Unlike previous studies, we found no A. parasiticus or A. flavus capable of both B- and G-type aflatoxin production in any of the samples. A. pseudotamarii, which had not been previously reported from Thailand, was found in four soil samples. In two of the samples A. nomius was determined to be the most abundant aflatoxin-producing species. Based on sequence alignments for three DNA regions (Taka-amylase A (taa), the rRNA internal transcribed spacer (ITS), and the intergenic region for the aflatoxin biosynthesis genes aflJ and aflR) the A. nomius isolates separated into three well-supported clades. Isolates from one of the A. nomius clades had morphological properties similar to those found for S-type isolates capable of B and G aflatoxin production and could easily be mistaken for these isolates. Our results suggest that such unusual A. nomius isolates could be a previously unrecognized agent for aflatoxin contamination in Thailand.     

普洱茶中转化茶多酚的优势菌株筛选与鉴定

普洱茶是以晒青毛茶为原料,采用独特工艺加工而成的一种发酵性茶叶,其中微生物的发酵对普洱茶的品质形成起着决定性作用。为了提高普洱茶品质和缩短发酵周期,本研究对普洱熟茶样品中转化茶多酚的微生物进行筛选与鉴定。经过固体平板初筛和液体茶汤培养复筛,得到3株氧化茶多酚形成茶褐素能力较强的菌株。将这3株菌回接普洱茶固态发酵,明显促进了茶多酚转化为茶色素,并改善了3种茶色素的比例。分子生物学鉴定结果表明,这3株菌分别为黑曲霉(Aspergillus niger)、布朗克假丝酵母(Candida blankii)和泡盛曲霉(Aspergillus awamori)。