广东烟草青枯病菌菌系研究

广东主要烟区南雄县和梅州市的烟草青枯病菌（Ｒａｌｓｔｏｎｉａｓｏｌａｎａｃｅａｒｕｍ）没有本质上的差异。供试的菌株对烟草、茄子、番茄、辣椒都有强致病力,均为小种１,对２个花生品种（汕油７１,蔓生型）的致病力均分化为３个类型。所有菌株都能利用３糖３醇产酸,为生化型Ⅲ。琼脂双扩散试验结果表明,绝大部分菌株都能与南雄菌株和大埔菌株的抗血清形成３条吻合相连的沉淀带,说明这两个烟草青枯病菌菌株的亲缘关系十分密切。     

大蒜粗提物对烟草青枯病菌的室内抑制作用测定

在实验室测定了大蒜乙醇和水提取物对烟草青枯病菌的抑菌效果.结果表明:大蒜提取物均对烟草青枯病菌有明显的抑制作用.且随大蒜提取物浓度的增大而增强;大蒜乙醇提取物对烟草青枯菌的抑制作用优于大蒜水提取物.0.2、0.3和0.4 g/mL浓度的大蒜乙醇提取物对烟草青枯痛菌的抑制率分别为65.56%、69.26%、75.93%;0.3和0.4g/mL浓度的大蒜水提取物的抑制率分别为61.85%和72.59%;大蒜水与乙醇提取物的有效抑制中浓度分别为0.14和0.08 g/mL.因此,可尝试以大蒜为原料研制植物保护剂来防治烟草青枯病.     

四种杀菌剂对烟草青枯病菌的毒力比较

为筛选对烟草青枯病菌更具抑菌作用的杀菌剂,采用"改良抑菌圈法"测定了4种杀菌剂对烟草青枯病菌的毒力。结果表明:4种杀菌剂抑菌率随浓度提高,青枯灵、农用硫酸链霉素和克菌康在1450.0、310.0和700.0 mg·L-1浓度下,72 h时抑菌率分别达到94.3%、89.1%和84.4%,辛菌胺醋酸盐的抑菌率在48 h时达到最高78.1%。4种药剂对烟草青枯病菌的毒力大小依次为农用硫酸链霉素辛菌胺醋酸盐青枯灵克菌康,前两者EC50分别为274.57 mg·L-1和148.25 mg·L-1。表明辛菌胺醋酸盐和农用硫酸链霉素是防控烟草青枯病较为理想的杀菌剂。     

豫南烟区烟草青枯病菌的致病力及遗传多样性分析

为有效防控豫南烟区烟草青枯病,对来自信阳市罗山县、驻马店市确山县和遂平县的烟草青枯病菌的致病力和遗传多样性进行了测定分析。人工接种试验表明,豫南烟区烟草青枯病菌的致病力分为强、中和弱3种,不同寄主来源的烟草青枯病菌具有显著的致病力差异。从100个随机引物中筛选出8个扩增条带清晰且具有丰富多态性的引物用于不同地区烟草青枯病菌菌株DNA的RAPD分析,共扩增出720条带,其中多态性带占88.9%。聚类结果和遗传相似系数分析显示,供试菌株可分为A、B两大类,遗传相似系数范围为0.49~1.00,且供试菌株间的遗传相似性与其地理来源有一定的相关性。综上所述,豫南烟区烟草青枯病菌的致病力存在明显差异且其DNA具有丰富的遗传多样性。     

重庆地区烟草青枯病菌的生物型测定

从重庆市黔江区、酉阳县、武隆县烟田采集的烟草青枯病典型病株中,分离获得了44个菌株,进行了鞭毛染色和致病性测定,并进一步研究了菌株对双糖和己醇的利用能力以及对硝酸盐的还原作用、产气情况。结果显示:44个菌株的菌体形态均与青枯病菌菌体形态一致,且均具有致病性;这些菌株均属于生物型Ⅲ,无亚型及其它生物型。     

重庆地区烟草青枯病菌生理小种的初步鉴定

从重庆市黔江区、酉阳县、武隆县烟田采集的烟草青枯病典型病株中,分离获得44个致病的青枯病菌株,并进行了生理小种的初步鉴定.根据在生理小种鉴另q寄主上的反应和烟叶浸润反应、黑色素产生试验,将44个菌株初步划为1号生理小种,其中35个菌株对所有鉴别寄主表现出高度致病性,在6个鉴别寄主上平均病情指数在90以上的菌株有10株,它们分布在黔江区水田乡、新华乡和武隆县黄莺乡、仙女山镇.     

基于致病基因靶点的PCR法特异性检测土壤青枯菌

利用分子生物学手段,以R.solanacearum染色体上的16S rDNA ITS以及毒性质粒携带的致病性相关基因fliC为靶点,分别设计5对序列特异性引物,筛选得到了特异性扩增16SrDNA ITS保守序列的引物对RaITS-1/2以及特异性扩增病菌fliC基因片段的引物对RalfliC-F/R.比较这两对引物的扩增灵敏度、稳定性和特异性可以发现,它们均能够稳定、快速、灵敏地检测青枯菌DNA,检测灵敏度可以达到10 fg DNA/μL.在此基础上成功构建了直接检测土壤青枯菌DNA的PCR检测技术体系.     

玉米内州萎蔫病菌的巢式PCR检测方法

目的建立了一种特异、敏感、快速的玉米内州萎蔫病菌的巢式PCR(Nest-PCR)检测方法。方法根据玉米内州萎蔫病菌(Clavibacter michiganensis subsp.Nebraskensis,Cmn)和C.michganensis种下其他4个亚种细菌Cmm、Cmi、Cms、Cmt的ITS序列差异性基因位点设计Cmn FP-OUTER/Cmn RP-OUTER为外侧引物,Cmn FP-INNER/Cmn RP-INNER为内侧引物的巢式-PCR,并对所有参试菌株DNA和菌悬液进行了扩增。结果经过两轮扩增,能从参试的玉米内州萎蔫病菌中特异性地扩增出1条122 bp的片段,而其他参试菌株没有扩增信号。该巢式PCR检测方法对菌悬液的最低检测限为3.54×102 CFU/m L,检测灵敏度比常规PCR提高了1000倍。结论本研究建立的玉米内州萎蔫病菌的巢式PCR(nest-PCR)检测方法具有良好的特异性和灵敏性,将会在玉米内州萎蔫病的早期诊断及预防传入方面发挥重要作用。     

壳聚糖处理对两种马铃薯干腐病菌的抑制效果比较

由镰刀菌(Fusarium)引起的干腐病是马铃薯块茎采后的重要病害。本文通过体外和体内实验测定了不同浓度壳聚糖处理对马铃薯干腐病菌的抑制效果。结果表明,体外条件下壳聚糖处理能够有效抑制F.sulphureum和F.sambucinum的孢子萌发,不同浓度壳聚糖处理后F.sulphureum的孢子萌发相比对照下降了92%,F.sambucinum的孢子萌发几乎完全被抑制。壳聚糖处理能够有效抑制F.sulphureum和F.sambucinum的菌落直径的扩展,其中以0.25%处理效果最好,比同期对照分别下降7.46%和8.9%,且对F.sambucinum的抑制效果较好。壳聚糖处理可显著降低F.sulphureum和F.sambucinum损伤接种马铃薯块茎切片的病斑直径,0.25%的壳聚糖处理者的病斑直径分别低于对照45.3%和34.5%,更高浓度处理并没有增加抑制效果。由此表明,壳聚糖可通过直接抑菌抑制马铃薯的干腐病。      

The influence of dehydrated potatoes processing on the glycoalkaloids content in coloured-fleshed potato

The aim of this study was to determine the effect of different temperatures of blanching and pre-drying used in the laboratory production of dried potato dice on the content of glycoalkaloids in red and blue fleshed potato varieties.     

利用马铃薯为原料制醋酒精发酵工艺的优化

为了开发新的食醋品种,研究了以马铃薯为原料制醋工艺中酒精发酵工艺。利用3因素3水平正交试验法,通过对蒸煮温度、蒸煮时间和酒精发酵温度这三个对酒精发酵有重大影响作用的因素进行优化,得到酒精发酵最佳条件为：蒸煮温度130 ℃、蒸煮时间4 min和发酵温度30 ℃。在此最佳发酵工艺条件下,酒精发酵的酒精度可达12.4%vol。     

烟曲霉检测技术研究进展

烟曲霉(Aspergillus fumigatus)是一种广泛存在的致病真菌,烟曲霉及其毒素可严重污染粮食与饲料制品,危害人和动物的健康,造成很大的经济损失,因而烟曲霉的快速准确检测对于食品安全,疾病的快速诊断等有着重要意义。基于近年来国内外的研究报道,介绍了烟曲霉检测技术的进展,并对所涉及的微生物培养,免疫学和分子生物学方法等检测技术进行了比较。     

The influence of thermal process of coloured potatoes on the content of glycoalkaloids in the potato products

Potato products made from potato varieties with coloured flesh (red and blue-fleshed potatoes) may be an interesting alternative to traditional products. The purpose of this study was to determine the influence of peeling, cooking and frying of red and blue-fleshed potato tubers on the content of glycoalkaloids (α-solanine and α-chaconine) in processed potato products. The material taken for the study consisted of seven coloured potato varieties. French fries and crisps were prepared from two potato variety: Rosalinde and Blue Congo. The content of total glycoalkaloids (TGA) in raw material before and after peeling, in cooked unpeeled and peeled potatoes and also in fried potato products have been determined by HPLC method.     

生物检测技术在食品检验中的研究

生物检测技术在食品检验中应用越来越广泛，对食品检测中的主要生物检测方法及其主要应用领域进行了综述，并对发展前景做了展望。     

Determination of the glycoalkaloid content of potato tubers by three methods including enzyme-linked immunosorbent assay

Potato tuber samples of diverse genetic backgrounds were analysed independently for total glycoalkaloid content by three different procedures. Two of the methods used were conventional chemical assays, the third an enzyme-linked immunosorbent assay (ELISA). Agreement between all three was extremely good, though the ELISA employed much simpler sample preparation, was technically easier to carry out, and could assay more rapidly large numbers of samples. For these and other reasons, the ELISA will find wider application in future.     

Starch transformation and structure development in production and reconstitution of potato flakes

Changes of parenchymous tissue structure and transformations of starch in the production and reconstitution of drum-dried potato flakes as instant mashed potatoes were investigated by light microscopy, iodine binding capacity, thermal analysis, wide-angle X-ray powder diffraction and rheology. Instant mashed potatoes are suspensions which are formed by separating whole potato tissue into individual cells. Mechanical stress during mashing and the subsequent steps also lead to undesirable cell disruption and extracellular starch. The stabilizing effect on starch by gelatinization and retrogradation in the preheating and cooling step was found to be far less important than mentioned in literature. While amylopectin does not retrograde, amylose crystallizes de novo during preheating, probably further aggregates during the cooling step and the ageing of mashed potatoes and melts fully during drum drying. The total amount of cells and the proportion of single cells to cell clusters as dispersed phase determine product flow properties as much as the amount of extracellular starch in the continuous fluid phase. Therefore, the iodine binding value of extracellular starch cannot serve as only measure to judge texture of mashed potato products.     

Monitoring of acrylamide concentrations in potato chips in Japan between 2006 and 2010

Acrylamide levels in commercially available potato chips in Japan were monitored between August 2006 and June 2010 using the xanthydrol derivative gas chromatography-mass spectrometry (GC-MS) method. Seasonal and annual changes in acrylamide concentrations were determined. Nationwide bimonthly sampling of potato chips was carried out using a four-level design, and seasonal variations were detected in which the minimum acrylamide concentration was observed in August, and the maximum between February and June. Seasonal variations became less apparent after August 2008 as a result of annual effects and/or mitigation measures taken by the potato chip producers. Sampling uncertainties were separated into time-to-time, city-to-city, and lot-to-lot variation, and the largest variation was shown to be lot-to-lot including bag-to-bag.