基于特征荧光信号的去囊衣带芯橘瓣分选

为实现去囊衣带芯橘瓣的机器视觉分选,给去囊衣带芯橘瓣的机器识别提供直接、准确的判别信号,采用荧光分光光度计对50颗去囊衣带芯橘瓣的橘芯和砂囊分别进行三维荧光光谱扫描,通过对橘芯、砂囊平均三维荧光光谱分析,确定了橘芯相对砂囊的特征荧光信号,据此对带芯橘瓣荧光图像识别的可行性进行了验证。检测发现,在370~390 nm紫外光激发下,橘芯和砂囊在440 nm处的荧光强度差异较大;橘芯与砂囊在370 nm紫外光激发下,440 nm处荧光强度分布的箱线图表明两者荧光强度分布存在明显差异,且以橘芯在440 nm处荧光强度的下四分位数(Q1)与砂囊在440 nm处荧光强度的上四分位数(Q3)的平均值作为分类标准,去囊衣带芯橘瓣检出准确率可达85%。对(370±2)nm激发下得到的单色(440±5)nm荧光图像进行二值化及形态学处理后,可在以砂囊为背景的橘瓣图形中显现橘芯亮斑。利用橘芯与砂囊的荧光特性差异进行机器视觉成像分析,可作为识别去囊衣带芯橘瓣的一种有效方法。     

培养温度、水分活度对稻谷和大米黄曲霉生长及产毒的影响

为了解析不同培养温度和水分活度对稻谷和大米黄曲霉生长和产毒的影响,揭示温度和水分活度(a_w)调控稻米上黄曲霉生长和产毒的分子机制,以湖南黄华占稻谷和黑龙江稻花香大米为原料,分析稻谷和大米的真菌菌相,并采用高效液相色谱法测定稻谷和大米AFB₁含量,利用荧光定量PCR分析稻谷和大米水分活度及温度对黄曲霉毒素生物合成关键基因表达的影响。结果表明,当a_w降低至0.75以下,稻谷和大米上不适合黄曲霉生长繁殖和产毒。在33℃、a_w为0.96条件下大米黄曲霉产毒最多,33℃、a_w为0.90条件下大米黄曲霉的生长最好;稻谷则是在温度37℃,a_w为0.94和0.92条件下分别为最适产毒和生长,可见黄曲霉在稻谷和大米上生长和产毒的最适条件并不统一。荧光定量PCR结果显示,低温25℃可以促进黄曲霉产毒基因表达,但毒素在转录合成过程中受到了阻抑,高温37℃则抑制部分结构基因的表达,但菌的生长受到极显著影响而导致毒素量极低。因此,稻谷和大米储藏期及加工时,保持较低的a_w是有效预防黄曲霉侵染及AFB₁污染的关键。本研究结果为制定储藏及加工期稻谷和大米黄曲霉毒素污染的防控措施提供了一定的理论依据和数据支撑。     

航空施药雾滴沉积特性光谱分析检测系统研发与应用

为快速获取航空施药雾滴沉积的连续分布特性,弥补传统离散样点取样方式检测不足,提升航空施药雾滴沉积特性检测准确性,该文结合光谱分析和荧光激发技术设计研发了基于光谱分析的航空施药沉积特性检测系统。系统包括信息采集模块、采集装置模块和数据处理模块3部分。配置质量分数1.0%的荧光示踪剂溶液,采用农用植保无人机现场喷洒作业,同步放置雾滴获取介质和水敏试纸样本采集雾滴分布,系统采集雾滴获取介质的光谱特征曲线。与水敏试纸图像分析获取的雾滴沉积特性参数结果对比分析,结果表明:雾滴获取介质上的荧光示踪剂在450~460 nm和500~520 nm波段范围内产生显著荧光效应,其光谱平均值与雾滴沉积特性参数呈显著正相关。计算出450~460 nm和500~520 nm波段范围光谱平均值,建立雾滴沉积特性参数的检测多元线性回归模型,建模决定系数达0.80以上,验证决定系数达0.83以上,达到了较为理想的拟合结果。     

臭氧降解花生中黄曲霉毒素的设备及应用

为了高效降解花生中黄曲霉毒素,研制了一套臭氧降解黄曲霉毒素的设备。以人为污染的花生为试验材料,利用此设备研究了臭氧处理时间及其相对湿度对花生脱毒效果的影响。研究结果表明:臭氧能有效降解花生中的黄曲霉毒素,且臭氧处理时间和相对湿度显著影响其降解效果(P<0.05)。在臭氧浓度89mg/L、流速1L/min、搅拌速度70r/min条件下,黄曲霉毒素的较佳降解工艺为:臭氧相对湿度50%,处理时间30min。在此条件下,花生中黄曲霉毒素B1、B2、G1和G2的含量分别从87.53、21.99、9.71和4.38μg/kg降低到15.23、8.31、2.81和2.11μg/kg,降解率分别为82.6%、62.2%、71.1%和51.8%。研究结果可为花生贮藏和加工企业降低花生中的黄曲霉毒素、确保花生食用安全性提供技术参考。     

黄桃表面缺陷和可溶性固形物光谱同时在线检测

表面缺陷和可溶性固形物是评价黄桃品质的重要指标,采用可见/近红外漫透射光谱技术,探讨黄桃表面缺陷与可溶性固形物同时在线检测的可行性。在运动速度为5个/s、积分时间100 ms、光照强度1 000 W的条件下采集黄桃表面缺陷果与正常果的近红外漫透射光谱。对比分析了同一个黄桃样品损伤前后的光谱特征,建立了黄桃的最小二乘支持向相机判别模型与偏最小二乘判别模型。同时建立了黄桃可溶性固形物偏最小二乘回归模型并采用连续投影算法对模型进行优化,研究了表面缺陷果对黄桃可溶性固形物检测模型精度的影响,最终实现了黄桃表面缺陷与可溶性固形物同时在线检测。采用未参与建模的样品来评价模型的在线分选的准确性,其中表面缺陷果的正确判断率为100%,可溶性固形物分选准确率达到93%。试验结果表明:黄桃表面缺陷与可溶性固形物同时在线检测是可行的,研究可为黄桃在线分选提供技术参考和理论依据。     

基于高光谱荧光技术的叶菜农药残留快速检测

为了解决现有农药残留检测手段费时、复杂、前处理过程繁琐等不足,结合高光谱成像技术和荧光激发技术,搭建了高光谱荧光成像农药残留检测系统。在400～1 100 nm范围内获取叶菜表面毒死蜱的高光谱荧光图像,使用ENVI 4.3软件提取了农药的荧光光谱信息。研究结果表明,毒死蜱在甲醇溶液中具有较强的荧光特性,在437 nm附近产生荧光发射光谱,并且不同浓度的毒死蜱农药具有不同的荧光发射光谱峰值,随着农药浓度的降低其荧光特征峰值也降低。研究结果可为进一步开发和研究快速、精确的农药残留检测仪器提供理论依据。     

高产漆酶平菇的筛选及其在降解黄曲霉毒素B1中的应用

通过选择培养基平板培养法和液体发酵培养法筛选得到2株高产漆酶的平菇菌株P1和P2,并对平菇菌株产漆酶的培养基进行筛选,得到产漆酶的最适培养基为最低盐MSM培养基。菌株P1不仅产漆酶能力最高,而且降解黄曲霉毒素的能力也最好。在MSM培养基中培养10d时,产漆酶量高达769.44U/L,在800μl的反应体系中,790μl粗酶液可以将1000ng黄曲霉毒素B₁降解到222.62ng,降解率为77.74%,并且平菇粗酶液降解黄曲霉毒素B₁的能力与其中漆酶的含量呈一定的正相关性。     

检测马西尼罗热病毒抗体的重组E蛋白-ELISA的建立

摘要：重组质粒pET-E转化宿主菌 BL21，经1.0mmol/L IPTG 诱导，外源基因以包含体的形式获得高效表达。通过Western blotting 检测证明表达产物具有良好的抗原性。以纯化后表达产物作为诊断抗原包被酶标板建立了检测WNV抗体的间接ELISA方法。结果表明，抗原的最佳稀释度为8.6ug/mL，血清的最佳稀释度为1：100，待检血清阳性标准初步定为：OD490nm＞2.1×OD490阴性。用此方法检测了450 份血清样品，结果全为阴性。     

作物叶片表面农药残留的便携式检测仪器的设计与试验

针对现有的农药残留检测仪器只能检测水溶液体系中的农药残留和检测对象较为单一的问题,该研究以不同植物叶片啶虫脒农药残留为研究对象,探究了利用荧光强度检测叶片表面农药残留的可行性,设计了一款叶片表面农药残留的便携式检测仪器。首先,通过啶虫脒农药叶片表面喷洒试验,采集叶片的荧光光谱并进行特征分析,发现啶虫脒农药的最佳激发波长和最佳发射波长分别为355和500 nm,从而确定光源和光电信号接收源的特征波长分别为350和500 nm。然后,通过获取最佳光源照射角度以及光照距离,优化光路结构减少叶片表面杂散光的干扰。同时,设计相关检测电路(光源电路、信号调理电路、控制电路等)测出表征反射光强度的电压值,构建电压值与农药残留值之间的线性方程,设计便携式检测仪对农药残留进行检测。结果表明:1)荧光强度与农药浓度在1～5 mg/L的范围内成正比;2)确定了检测仪器最佳光照角度为45°,光源和待测叶片之间的最佳垂直距离为3.46 cm;3)方程决定系数达到了0.875,均方根误差为0.405 mg/L。该研究所设计的便携式荧光光谱仪能够快速、准确、无损检测叶片表面农药残留。     

反射光谱估算滨海土壤黏粒含量

探明反射光谱估算土壤黏粒含量的成因是实现黏粒含量测定、提高估算精度的基础。该文以江苏省滨海平原的150个土壤样品为研究对象,将测得的原始光谱数据进行平滑、一阶导数、连续统去除和倒数等数据变换,采用逐步多元线性回归(stepwise multiple linear regression,SMLR)和偏最小二乘回归(partial least squares regression,PLSR)方法估算黏粒含量,并在此基础上分析建模的影响波段,探讨反射光谱估算土壤黏粒含量的成因。结果表明,连续统去除光谱数据的SMLR分析估算精度最高,建模集和验证集决定系数分别为0.941和0.750。360~900、1 800~2 490 nm是黏粒含量的重要建模影响波段,该建模影响波段主要包括铁离子(410 nm附近)、土壤有机质(500~800 nm)、层状硅酸盐中的结晶水(1 900 nm附近)、绿泥石和蛭石等黏土矿物(2 325 nm)的吸收特征波段;PLSR分析表明,1 400 nm附近回归系数出现的双峰特征源于高岭石的双峰吸收。黏粒中的黏土矿物、黏粒对铁离子的吸附特性以及黏粒与有机质的高度相关性是实现反射光谱估算滨海土壤黏粒含量的原因。     

Fluorescence Tracing of Diffuse Landfill Leachate Contamination in Rivers

Landfill leachates are composed of a complex mixture of degradation products which include a wide range of potentially fluorescent organic molecules and compounds. Here we investigate the use of fluorescence excitation–emission matrix (EEM) analysis in detecting diffuse landfill leachate contamination in rivers. Landfill leachates from three unlined landfill sites adjacent to our study river are characterised by intense fluorescence at excitation wavelength 220–230 nm, and emission wavelength 340–370 nm, which derives from fluorescent components of the xenobiotic organic matter fraction. Seven surface water sample sites on an adjacent polluted river system were analysed for fluorescence and water quality properties. The 220–230 nm excitation wavelength, 340–370 nm emission wavelength fluorescent centre was also detected in this river system at the sample locations downstream of the landfills, but not at upstream control sites, demonstrating its use as a tracer of landfill leachate contamination. Negative correlations are observed between this fluorescence centre and dissolved oxygen in the river water samples, demonstrating the water quality implications of leachate contamination at this study site. The fluorescence intensity at the 220–230 nm excitation wavelength, 340–370 nm emission wavelength fluorescent centre in landfill leachates is such that it remains detectable at dilutions of 10²–10³, and the fluorescence EEM technique is rapid and cost-effective for use by river managers and water quality regulators.     

Simple Measurement of 4,4’-bis(2-sulfostyryl)-biphenyl in River Water by Fluorescence Analysis and Its Application as an Indicator of Domestic Wastewater Contamination

A characteristic peak of fluorescent whitening agents (FWAs) was detected by fluorescence excitation spectrum (FES) measurement of river water samples. The main causative chemical was 4,4’-bis(2-sulfostyryl)-biphenyl (DSBP), which is commonly added to household detergents in Japan. As the fluorescence of DSBP overlaps with that of fulvic-like organic matter in the spectral fluorescent signatures, DSBP concentration was determined by the newly proposed calculation method, which uses fluorescence intensity at three excitation wavelengths of 320, 345 and 360 nm at emission wavelength of 430 nm for baseline correction. The concentration of DSBP calculated using this method showed strong correlation (correlation coefficient: r = 0.992) with that obtained by high-performance liquid chromatography analysis. The concentrations of DSBP detected in river water samples were 0.28 to 1.84 μg l^?1, with high concentrations observed at the stations with relatively high flow rates of upstream sources of treated domestic wastewater and untreated gray water (domestic wastewater excluding flush toilet wastewater). It was proved that the concentration of DSBP in river water is useful for giving rough estimation of the magnitude of domestic wastewater contamination in river water.     

Reduction of Aflatoxin and Fumonisin Contamination in Yellow Corn by High‐Speed Dual‐Wavelength Sorting

A high‐speed dual‐wavelength sorter was tested for removing corn contaminated in the field with aflatoxin and fumonisin. To achieve accurate sorting, single kernel reflectance spectra (500–1,700 nm) were analyzed to select the optimal pair of optical filters to detect mycotoxin‐contaminated corn during high‐speed sorting. A routine, based on discriminant analysis, was developed to select the two absorbance bands in the spectra that would give the greatest classification accuracy. In a laboratory setting, and with the kernels stationary, absorbances at 750 and 1,200 nm could correctly identify >99% of the kernels as aflatoxin‐contaminated (>100 ppb) or uncontaminated. A high‐speed sorter was tested using the selected filter pair for corn samples inoculated with Aspergillus flavus; naturally infested corn grown in central Illinois; and naturally infested, commercially grown and harvested corn from eastern Kansas (2002 harvest). For the Kansas corn, the sorter was able to reduce aflatoxin levels by 81% from an initial average of 53 ppb, while fumonisin levels in the same grain samples were reduced an average of 85% from an initial level of 17 ppm. Similar reductions in mycotoxin levels were observed after high‐speed sorting of A. flavus inoculated and naturally mold‐infested corn grown in Illinois.     

Liquid chromatographic method for determination of aflatoxins B1, B2, G1, and G2 in corn and peanut products: collaborative study

A collaborative study of a liquid chromatographic method for the determination of aflatoxins B1, B2, G1, and G2 was conducted in laboratories located in the United States, Canada, South Africa, and Switzerland. Twenty-one artificially contaminated raw peanuts, peanut butter, and corn samples containing varying amounts of aflatoxins B1, B2, G1, and G2 were distributed to participating laboratories. The test portion was extracted with methanol-0.1N HCl (4 + 1), filtered, defatted with hexane, and then partitioned with methylene chloride. The concentrated extract was passed through a silica gel column. Aflatoxins B1 and G1 were derivatized with trifluoroacetic acid, and the individual aflatoxins were determined by reverse-phase liquid chromatography with fluorescence detection. Statistical analysis of the data was performed to determine or confirm outliers, and to compute repeatability and reproducibility of the method. For corn, relative standard deviations for repeatability (RSDr) for aflatoxin B1 ranged from 27.2 to 8.3% for contamination levels from 5 through 50 ng/g. For raw peanuts and peanut butter, RSDr values for aflatoxin B1 were 35.0 to 41.2% and 11.2 to 19.1%, respectively, for contamination levels from 5 through 25 ng/g. RSDr values for aflatoxins B2, G1, and G2 were similar. Relative standard deviations for reproducibility (RSDr) for aflatoxin B1 ranged from 15.8 to 38.4%, 24.4 to 33.4%, and 43.9 to 54.0% for corn, peanut butter, and raw peanuts, respectively. The method has been adopted official first action for the determination of aflatoxins B1, B2, G1, and G2 in peanut butter and corn at concentrations greater than or equal to 13 ng total aflatoxins/g.     

大豆丛枝菌根共生结构和多聚磷累积双定位方法

【目的】多聚磷是丛枝菌根内磷的主要贮存形式,定性、定量观察多聚磷对于解析菌根中磷代谢具有重要意义。随着植物体内越来越多的参与菌根真菌与寄主植物之间营养交换过程的基因被鉴定,迫切需要进一步提高根内菌根共生结构和多聚磷累积的染色和定位分析技术。【方法】本研究利用丛枝菌根真菌Glomus mosseae侵染的大豆植株,采集新鲜根样制片,一部分薄根片利用低浓度荧光染料麦胚凝集素,室温染色30 min,在波长488 nm的蓝光激发下使用荧光显微镜观察拍照;另一部分薄根片利用荧光染料4’,6-二脒基-2-苯基吲哚二盐酸盐(DAPI)进行染色,在波长405 nm紫外光激发下观察并拍照;进一步取新鲜制备的薄根片,先后用以上两种荧光染料进行染色,分别在波长405 nm和488 nm的激发光下观察并拍照,完成了菌根共生结构和多聚磷的共定位。【结果】1)使用荧光染料麦胚凝集素,大豆丛枝菌根真菌侵染结构的荧光标记活性染色法,可以清晰地检测到大豆丛枝菌根中所有的共生结构,包括丛枝,泡囊和根内菌丝等。2)在丛枝菌根真菌侵染的根中,各种共生结构都呈现出黄色荧光,为DAPI与多聚磷结合在紫外光激发下的呈色。根段中部分细胞内的蓝白色斑点为DAPI与细胞核中DNA结合的显色结果。在含有成熟丛枝结构的细胞中,也可观察到大部分丛枝呈蓝白色,主要是丛枝膜质结构的呈色。因此,利用荧光染料4’,6-二脒基-2-苯基吲哚二盐酸盐染色法定位多聚磷,能很好地区分多聚磷酸盐、DNA和膜质。3)在以上研究的基础上,通过荧光光路的切换,可以同时观察到菌根共生结构和多聚磷的共定位。处于发育阶段的整个丛枝中多聚磷累积的亮黄色清晰可见。在成熟的丛枝中,由于膜质结构发达,对累积在丛枝结构中的多聚磷的染色观察产生了一定影响,导致仅仅局部的多聚磷累积清晰可见。【结论】本研究建立的大豆菌根共生结构与多聚磷累积的双定位分析系统,能够直观观察植物与丛枝菌根真菌的养分交换,清晰地对丛枝菌根共生结构中多聚磷的累积进行定位分析,可作为从组织和细胞水平研究菌根共生体的重要技术手段。     

Authentication of the botanical origin of honey by front-face fluorescence spectroscopy. A preliminary study

The potential of front-face fluorescence spectroscopy for the authentication of unifloral and polyfloral honey types (n = 57 samples) previously classified using traditional methods such as chemical, pollen, and sensory analysis was evaluated. Emission spectra were recorded between 280 and 480 nm (excit: 250 nm), 305 and 500 nm (excit: 290 nm), and 380 and 600 nm (excit: 373 nm) directly on honey samples. In addition, excitation spectra (290-440 nm) were recorded with the emission measured at 450 nm. A total of four different spectral data sets were considered for data analysis. After normalization of the spectra, chemometric evaluation of the spectral data was carried out using principal component analysis (PCA) and linear discriminant analysis (LDA). The rate of correct classification ranged from 36% to 100% by using single spectral data sets (250, 290, 373, 450 nm) and from 73% to 100% by combining these four data sets. For alpine polyfloral honey and the unifloral varieties investigated (acacia, alpine rose, honeydew, chestnut, and rape), correct classification ranged from 96% to 100%. This preliminary study indicates that front-face fluorescence spectroscopy is a promising technique for the authentication of the botanical origin of honey. It is nondestructive, rapid, easy to use, and inexpensive. The use of additional excitation wavelengths between 320 and 440 nm could increase the correct classification of the less characteristic fluorescent varieties.     

种植至储藏期花生黄曲霉毒素B_1污染研究

为解析种植至储藏期花生受黄曲霉侵染及黄曲霉毒素B1(AFB_1)污染的规律,揭示花生AFB_1污染的源头及主要影响因素,选取种植湛红2号和湛油75的花生田,采集种植期花生果和土壤及储藏1~4个月的花生果,分析花生和土壤真菌菌相,并采用高效液相色谱法测定花生AFB_1含量。结果表明,种植期黄曲霉侵染花生果主要发生在成熟期,但黄曲霉污染率均在8%以下;湛油75花生田土壤黄曲霉菌落数显著低于湛红2号,但花生果黄曲霉污染率显著高于湛红2号,表明湛红2号具有一定的黄曲霉抗性;湛油75和湛红2号分别在110 d和120 d检测到AFB_1,含量分别为3.37μg·kg~(-1)和2.08μg·kg~(-1),表明花生黄曲霉毒素含量与污染率呈正相关。储藏期花生果中未检测到黄曲霉和AFB_1,这主要是由于花生晾晒后水活度(aw)降低至0.70以下,不适合黄曲霉生长繁殖和毒素生物合成。综上,黄曲霉在荚果成熟期开始侵染花生果导致产生AFB_1,而储藏期保持较低的aw可有效预防黄曲霉及AFB_1污染。本研究结果为制定种植至储藏期花生黄曲霉毒素全程防控措施提供了理论依据。