Fungal infection and mycotoxin contamination of maize in the Humid forest and the western highlands of Cameroon

Fungal incidence and mycotoxin contamination of farm-stored maize were assessed and compared in grain samples from three villages each in two agroecological zones over time. Maize samples were collected at 2 and 4 months after stocking from 72 farmers’ stores in 1996 and 1997 in the Humid Forest (HF) and Western Highlands (WHL) of Cameroon. Mycological assays of these samples revealed several fungal species.Nigrospora spp. were the most prevalent fungi in HF (32%) and WHL (30%) in 1996,Fusarium verticillioides (22%) andF. graminearum (27%) were also isolated from these samples. In the WHL in 1996, no significant difference in fungal incidence was found among villages for samples collected 2 months after harvest, but at 4 months incidence was significantly higherP<0.05). In 1997 the levels of fungal contamination were lower than in 1996. The incidence ofAspergillus spp. was low in general, ranging from 0.0 to 5.9% infected kernels. Analysis with thin layer chromatography detected low levels of aflatoxins in a few samples.F. verticillioides mycotoxin fumonisin Bi (300-26,000 ng/g) andF. graminearum metabolites deoxynivalenol (<100–l,300 ng/g) and zearalenone (<50–110 ng/g) were determined by means of polyclonal antibody competitive direct enzyme-linked immunosorbent assay. A significant correlation (r=0.72; P=0.0001) was found between the incidence ofF. graminearum and the contamination with deoxynivalenol. Storage time (2vs 4 months after stocking) had a significant positive effect (r=0.39; P=0.013) on the level of fumonisin B₁. This is the first report of the natural occurrence of these mycotoxins in maize in Cameroon.     

原花青素对玉米赤霉烯酮致小鼠肝脏、肾脏氧化损伤的保护作用

试验旨在研究原花青素(PC)是否对玉米赤霉烯酮(ZEA)中毒的小鼠肝脏及肾脏具有保护作用.选取40只日龄为8~9周、体重约为45 g的健康清洁级雄性昆明系小鼠,随机分为4组,对照组灌喂生理盐水,PC组灌喂100 mg/kg PC,ZEA组灌喂40 mg/kg ZEA,PC＋ZEA组灌喂100 mg/kg PC+40 mg/kg ZEA,眼球采血,颈椎处死后采取肝脏样本.测定肝脏组织中谷丙转氨酶(ALT)、谷草转氨酶(AST)、丙二醛(MDA)、超氧化物歧化酶(SOD)含量及血清中尿酸(UA)、尿素氮(BUN)含量.结果显示,与对照组相比,PC组各项指标差异均不显著(P>0.05),提示肝脏及肾脏没有明显的氧化损伤;与对照组相比,ZEA组的小鼠组织中谷草转氨酶、谷丙转氨酶及丙二醛含量显著或极显著升高(P<0.05;P<0.01),超氧化物歧化酶含量极显著降低(P<0.01),血清中尿酸、尿素氮含量极显著升高(P<0.01),提示肝脏及肾脏有严重的氧化损伤;PC+ZEA组的小鼠各项指标(除超氧化物歧化酶外)均显著或极显著低于ZEA组(P<0.05;P<0.01),提示其肝脏及肾脏氧化损伤程度低于ZEA组,PC对ZEA中毒小鼠的肝脏及肾脏氧化损伤有一定的保护作用.     

一株高效降解玉米赤霉烯酮的耐酸耐高温枯草芽孢杆菌的研究

为寻求更高效、实用的生物脱毒制剂,提高其应用范围,通过采集酸性、高温的温泉环境样品,筛选获得1株高效降解玉米赤霉烯酮(ZEN)的细菌菌株Y-33,并对该菌株生长和降解特性进行分析。结果表明,菌株Y-33在50℃、pH值5.0条件下孵育36 h,菌液对2 μg·mL^-1 ZEN的降解率高达93.79%,对20 μg·mL^-1 ZEN的降解率也达82.40%。从形态、生理生化特性及16S rDNA序列对菌株Y-33进行分析,初步鉴定为枯草芽孢杆菌(Bacillus subtilis)。该菌株发酵上清液在28℃条件下对ZEN降解率为62.02%。金属离子Mn²⁺能明显增强菌株Y-33发酵上清液对ZEN的降解能力,降解率达81.17%,而Zn²⁺严重抑制了Y-33发酵上清液对ZEN的降解能力,降解率仅为5.42%。本研究结果为ZEN解毒菌剂的开发与应用奠定了理论基础。     

Toxigenic Fusarium Species and Mycotoxins Associated with Maize Ear Rot in Europe

Several Fusarium species occurring worldwide on maize as causal agents of ear rot, are capable of producing mycotoxins in infected kernels, some of which have a notable impact on human and animal health. The main groups of Fusarium toxins commonly found are: trichothecenes, zearalenones, fumonisins, and moniliformin. In addition, beauvericin and fusaproliferin have been found in Fusarium-infected maize ears. Zearalenone and deoxynivalenol are commonly found in maize red ear rot, which is essentially caused by species of the Discolour section, particularly F. graminearum. Moreover, nivalenol and fusarenone-X were often found associated with the occasional occurrence of F. cerealis, and diacetoxyscirpenol and T-2 toxin with the occurrence of F. poae and F. sporotrichioides, respectively. In addition, the occurrence of F. avenaceum and F. subglutinans usually led to the accumulation of moniliformin. In maize pink ear rot, which is mainly caused by F. verticillioides, there is increasing evidence of the wide occurrence of fumonisin B₁. This carcinogenic toxin is usually found in association with moniliformin, beauvericin, and fusaproliferin, both in central Europe due to the co-occurrence of F. subglutinans, and in southern Europe where the spread of F. verticillioides is reinforced by the widespread presence of F. proliferatum capable of producing fumonisin B₁, moniliformin, beauvericin, and fusaproliferin.     

拉曼光谱法检测玉米中黄曲霉毒素B1和玉米赤霉烯酮

为提高激光拉曼光谱技术对不同霉变程度玉米中的黄曲霉毒素B1(AFB1)和玉米赤霉烯酮(ZEN)检测的准确率,本试验以6个不同霉变等级的玉米样品为研究对象进行拉曼光谱检测.首先采用迭代多项式拟合基线校正方法对原始拉曼光谱进行基线校正,去除荧光背景;然后采用多元散射校正(MSC)、标准正态变量变换(SNV)和高斯-洛伦兹混...     

玉米赤霉烯酮的污染和残留及其作用机制

玉米赤霉烯酮(ZEA)是由镰孢真菌产生的类雌激素毒素.本文综述了ZEA的污染现状及其在动物组织中的残留现状,并且总结了ZEA的可能作用机制.     

The combination of deoxynivalenol and zearalenone at permitted feed concentrations causes serious physiological effects in young pigs

This study was to investigate the effects of the combination of deoxynivalenol (DON) and zearalenone (ZON) on pigs. Twenty-four weaning piglets were divided into a control group fed a diet free of mycotoxins and a toxin group fed a diet containing 1 mg/kg DON and 250 µg/kg ZON. The results showed that supplementation of DON and ZON in diets had extensive effects on pigs. More specifically, DON and ZON caused levels of total protein, albumin, and globulin in sera to decrease (p < 0.05) by 14.5%, 6.5% and 11.3%, respectively, and at the same time increased (p < 0.05) the serum enzyme activities of γ-glutamyltransferase, aspartate aminotransferase and alanine aminotransferase by 72.0%, 32.6% and 36.6%, respectively. In addition, DON and ZON decreased (p < 0.05) the level of anti-classical swine fever antibody titers by 14.8%. Real-time PCR showed that DON and ZON caused the mRNA expression levels of IFN-γ, TNF-α, IL-2, to decrease (p < 0.05) by 36.0%, 29.0% and 35.4%, respectively. Histopathological studies demonstrated that DON and ZON caused abnormalities in the liver, spleen, lymph nodes, uterus, and kidney. The concentrations of DON and ZON used in this study are in line with the published critical values permitted by BML. Our study clearly put the standard and adequacy of safety measures for these toxins into question. The authors suggest that with the increasing availability of cellular and molecular technologies, it is time to revisit the safety standards for toxins in feeds so as to make feeds safer, providing consumers with safer products.     

玉米赤霉烯酮的高灵敏时间分辨荧光免疫分析

采用时间分辨荧光技术建立高灵敏的玉米赤霉烯酮（ZEN）间接竞争免疫分析法（ZEN-TRFIA）。以玉米赤霉烯酮人工抗原（ZEN-BSA）包被96孔板为固相抗原，与ZEN标准或样品中的ZEN共同竞争有限的抗ZEN的单抗；用稀土离子Eu3+标记的羊抗鼠抗体进行示踪。该方法的灵敏度为0.01 μg/L（10ppt），测量范围为0.01-20 μg/L，批内和批间变异分别为7.2%和14.6%，平均回收率为94.4%，与玉米赤霉醇（ZER）的交叉反应率为15.16%。7条不同时间进行的ZEN-TRFIA的效应点值ED20、ED50、ED80分别为0.156±0.035 μg/L、0.634±0.091 μg/L和2.595±0.274 μg/L。试剂盒4℃保质期超过6个月。研究表明，ZEN-TRFIA是目前报导的ZEN检测中较灵敏的方法，该分析方法稳定性好，货架期符合要求，可测范围宽，具有很好的应用前景。     

玉米赤霉烯酮化学发光免疫分析检测系统设计

为了保障粮食安全,该研究根据玉米赤霉烯酮抗原抗体反应,以及辣根过氧化物酶催化鲁米诺过氧化氢反应产生化学发光,设计一款应用于粮食行业的玉米赤霉烯酮检测系统。采用侧窗型高精度光电倍增管MD983以及16位AD转换芯片,实现化学发光强度信号的准确测量;步进电机驱动旋转精密转台,通过优化步进电机的S型脉冲驱动控制曲线参数,完成转台的高精度定位控制,实现光电倍增管的测试窗口和化学发光孔精确对准;通过精密直线导轨滑台驱动加样器的进给,实现反应液微米量级的准确微量加样。利用竞争性免疫分析方法,使得赤霉烯酮毒素为0 μg/kg情况下,化学发光反应具有最大发光量,解决真菌毒素低浓度情况下的检测精度难题。经过试验验证,系统检出限为0.1 μg/kg,样品加标回收率在90%以上,标准曲线决定系数为0.996 5,系统检测玉米赤霉烯酮的线性范围为0~60 μg/kg。研究表明建立的玉米赤霉烯酮检测系统满足国家粮食行业对于粮食中玉米赤霉烯酮含量检测要求,为真菌毒素检测仪器的国产化提供参考。     

Correlations among Fusarium culmorum head blight resistance, fungal colonization and mycotoxin contents in winter rye

Fusarium culmorum head blight infections may lead to accumulation of toxic metabolites in winter rye grain. To estimate the correlation between resistance traits, fungal colonization and accumulation of deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON) and zea-ralenone (ZEA), 27 winter rye single-cross hybrids were artificially inoculated in 1992 and 1993. Resistance traits were head blight rating and grain weight of the inoculated relative to the non-inoculated plots. Fungal colonization was determined by the analysis of ergosterol (ERG) content in the grain. Head blight rating and relative grain yield showed a medium to high disease severity and ERG indicated a considerable fungal colonization of the kernels with a mean of 85 mg/kg in 1992 and 66 mg/kg in 1993. DON content among genotypes ranged from 0.7–28 mg/kg in 1992 and from 11 to 35 mg/kg in 1993. 3-AcDON and ZEA contents were low in both years with overall means of 1.1 and 0.09 mg/kg, respectively. Across both years, considerable genotypic variation was found for head blight rating, relative grain weight, and ERG content with medium to high heritabilities (0.6–0.7). For the mycotoxin contents, however, genotype-year interaction variance was the most important source of variation. The correlations between relative grain weight and DON, 3-AcDON, or ZEA were low in 1992 (r ～ 0.3), but considerably higher in 1993 (r ～ 0.7, P = 0.01). In contrast, correlation between relative grain weight and ERG was significant in both years (r ～ 0.5, P = 0.01). In F. culmorum head blight infections, DON, 3-AcDON and ZEA contents appear to be affected, at least partially, by different environmental factors than resistance traits and fungal colonization.