木麻黄青枯病菌的分离及强致病菌株的筛选

[目的]筛选出强致病菌株用于木麻黄抗病育种研究工作。[方法]在广东沿海木麻黄青枯病发病区采集病根,开展病原菌两种不同分离方法的比较研究,对分离出的31个病株进行16s rRNA测序鉴定及致病性测定。[结果]采用稀释分离法及根系溢出法在TTC培养基上共分离出了31个病原菌株,根系溢出法操作简便,杂菌含量低,分离率在60%左右,可作为常规稀释分离法的补充。31个菌株进行分子鉴定,只有22个菌株扩增出了特异性条带,经测序比对确定这22个菌株为青枯菌。青枯菌株致病性测定结果显示菌株致病性在无性系间、菌株间及菌株与无性系间的交互作用均具有极显著差异(P0.01),不同接种方法间菌株致病性相关系数值较小,介于0.496 6~0.731 0之间,即室内水培接种与小苗盆栽接种不存在密切的直线相关关系。[结论]综合选择在不同无性系及不同接种方法中均具有较强致病性的GL-2、H、M、TC-1、F、Q菌株作为下一步木麻黄种质资源抗性鉴定及抗病育种研究试验菌株。     

The effects of strain and incremental improvements in feed form on d 28 to 42 male broiler performance

Feeding high-quality pellets to modern commercial broilers may maximize genetic potential; however, this typically requires an increased cost to produce feed. Therefore, it is important to determine if incremental improvements in feed form (FF) can increase performance of modern broiler strains. The current study was conducted to investigate the effects of feeding modest improvements in feed form (50, 60, 70, or 80% intact pellets; IP) to 2 commercial broiler strains (fast-growing or high-yield) on d 28 to 42 growth performance and processing variables. A common diet was manufactured to contain 80% IP, of which a portion was ground to create a total of 4 FF treatments varying in IP to ground pellet ratios: 50:50; 60:40; 70:30; and 80:20. Fast-growing (FG) birds demonstrated improvements in body weight (BW), BW gain (BWG), and feed conversion ratio (FCR) when compared to high-yield (HY) birds. For the main effect of FF, feeding 80 vs. 50% IP reduced d 28 to 42 FCR. Also, feeding birds 80% IP vs. all other FF treatments improved d 28 to 42 BWG and d 42 BW. A Strain × FF interaction established that FG broilers fed 50, 60, and 70% IP diets had higher d 43 total breast yield than HY birds fed the same FF treatments; however, both strains demonstrated similar total breast yield when 80% IP were fed, which suggests that FG broilers are less sensitive and HY broilers are more sensitive to increasing FF. These data suggest a distinct benefit for feeding improved FF from d 28 to 42 to modern broilers.     

Tonic immobility,heterophil to lymphocyte ratio,and organ weights in slow-growing chickens

Effects of sex and strain of bird on factors influencing welfare in chickens were investigated in 288 21-week-old Potchefstroom Koekoek (PK), Ovambo (OV), and Naked Neck (NN) chickens. The birds were allocated to 4 paddocks of Chloris gayana and a house subdivided into 4 pens. There were 12 males per strain and 12 females per strain in each paddock. Similarly, 12 males per strain and the same number of females were placed in each pen in the house. Twelve birds, 4 each of NN, OV, and PK, were randomly selected per paddock and per pen, and tonic immobility (TI) was determined. Ambient temperature and humidity were recorded and fitted into a PROC MIXED model as random effects, with strain and sex as main effects. On the last d of the trial, blood samples were collected from 9 (3 of each strain) randomly selected birds per paddock, via brachial venepuncture, using 5 mL syringes and 22 gauge needles. At slaughter, the liver and spleen were recovered and weighed immediately. Organ weights were expressed relative to body weight (BW) of each bird. Sex of bird influenced (P < 0.05) BW, spleen, and relative liver weights and heterophil to lymphocyte (H/L) ratio. Strain did not influence (P > 0.05) TI but affected (P < 0.05) all other parameters. Rearing system (P < 0.05) influenced all parameters. Strain × sex interactions were significant (P < 0.05) on all organ weights. Males appeared more stressed than females. The free-range system could minimize stress in birds though mechanisms should be devised to prevent attacks by predators. Perhaps future research could be designed to study similar parameters over a longer observation period using younger slow-growing chickens.     

金龟子绿僵菌对椰心叶甲的致病力

采用喷菌法接菌,测定5株金龟子绿僵菌对不同龄期椰心叶甲的致病力。结果表明:浓度为(1±0.5)×10~7孢子·mL~(-1)的孢子悬液接菌10 d后,各绿僵菌菌株对该虫不同发育阶段均有一定致病力。其中,以Ma1775菌株对椰心叶甲致病力最强,成虫校正死亡率和僵虫率分别为(67.96±3.66)%和(60.59±1.31)%,LT_(50)为(7.11±0.52)d;5龄幼虫校正死亡率和僵虫率分别为(78.53±2.73)%和(73.55±3.22)%,LT_(50)为(5.77±0.38)d;4龄幼虫校正死亡率和僵虫率分别为(82.59±2.48)%和(77.86±3.44)%,LT_(50)为(5.80±0.14)d;2~3龄幼虫校正死亡率和僵虫率分别为(73.46±4.60)%和(69.50±3.87)%,LT_(50)为(6.49±0.12)d。Ma1775菌株对该虫各发育阶段6 d的LC50分别为:3.52×10~8、7.13×10~7、2.48×10~7、7.69×10~7孢子·mL~(-1)。时间-剂量-死亡率(time-dose-mortality,TDM)模型分析结果表明椰心叶甲各发育阶段幼虫死亡高峰期均为3~7 d。因此,Ma1775菌株在椰心叶甲生物防治中有较大的应用潜力。     

2株枯草芽孢杆菌的分离鉴定及特性研究

【目的】寻求适合制作水产类微生态制剂的益生菌。【方法】从养鱼塘底泥和健康鲫鱼Carassius auratus肠道中分离芽孢杆菌,结合细菌形态学、生理生化特征和16S rRNA序列分析对其进行鉴定,对菌株安全性、高温耐受性、酸性耐受性、拮抗性及产酶情况等特性进行研究。【结果】分离到2株芽孢杆菌,分别命名为B1和B2,细菌形态学、生理生化特征和16S rRNA序列分析的结果显示,B1和B2均为枯草芽孢杆菌Bacillus subtilis。特性研究结果证实B1、B2菌株都具有较好的安全性、高温耐受性和酸性耐受性,可对致病性大肠埃希菌Escherichia coli、金黄色葡萄球菌Staphylococcus aureus、嗜水气单胞菌Aeromonas hydrophila以及温和气单胞菌A.sobria有良好的体外抑菌能力,均具有产脂肪酶、淀粉酶、蛋白酶和纤维素酶的能力。【结论】分离到2株性能优良的枯草芽孢杆菌,可将其作为水产微生态制剂的候选菌株。     

表面活性剂对加利利链霉菌AF1发酵的影响

【目的】研究表面活性剂对加利利链霉菌Streptomyces galilaeus AF1菌株发酵的影响。【方法】利用单因素试验优化表面活性剂的添加种类、初步浓度及最佳添加时间,采用Box-Behnken试验和响应面分析对表面活性剂添加质量浓度进行组合优化。流式细胞仪测定细胞荧光强度,确定表面活性剂对AF1菌株细胞膜的影响。【结果】表面活性剂的最优添加质量浓度:吐温–80为8.95 g·L~(–1)、曲拉通X–100为2.09 g·L~(–1)、山梨醇为3.89 g·L~(–1),最优添加时间为接种后5 d;细胞膜透性测定结果表明,试验组的AF1菌株细胞荧光强度极显著高于对照组。【结论】试验得到的响应面模型对因变量的解释程度达94.89%,具有实际意义;添加最优表面活性剂组合后,加利利链霉菌AF1的细胞膜通透性极显著增大,间接导致胞内活性物质的外排量增加,提高了抗菌活性物质的生物合成量。     

烟草青枯菌Tn5突变体库的构建及突变位点分析

为了从烟草青枯菌全基因组范围内发掘致病性相关基因,采用电转化法构建了一个EzTn5转座子介导的烟草青枯菌TXLLJ14-3菌株插入突变体库,该突变体库包含1.2万个突变子,经烟草上的致病性检测,共得到216个无致病力或弱致病力突变菌株。利用TAIL-PCR扩增获得其中15个无致病力烟草青枯菌的Tn5侧翼序列,并对其插入位点进行了分析,结果表明,15个突变菌株的插入位点分别位于核苷酸水解酶、糖基转移酶、转座酶和合成酶等具有不同功能的基因上,这些基因受到干扰或破坏后,可能会抑制致病相关物质的表达或分泌,或者诱导烟草对病原菌产生抗性,从而表现出无致病力特征。     

单菌株与复合菌在黄瓜种植中的应用效果

为了解功能菌单菌株与复合菌在蔬菜种植中的应用效果和差别,通过单菌株、复合菌与不施用菌株在黄瓜种植中的应用对比试验,观察黄瓜生长的抗病和增产效果。结果表明,与对照相比,各单菌株和复合菌对黄瓜成苗率、防病和增产效果方面均具有显著的促进作用,其中又以复合菌最佳,防病效果达60.20%,增产幅度达15.6%。由此可知,功能菌单菌株和复合菌在蔬菜中种植中均具有一定的菌肥功能,且以复合菌为佳。     

桑黄原生质体融合菌株及其亲本生物学特性的比较研究

摘要：目的 选择和评价桑黄原生质体融合菌株 方法 应用聚丙烯酰胺垂直平板凝胶电泳技术, 对5个供试菌株的酯酶同工酶进行测定,并对供试菌株进行液体培养,测定各菌株的生物量及发酵液中胞外多糖含量、总黄酮含量、酯酶活性及pH。 结果 融合菌株与亲本具有共同的基础条带,同时还产生了自身特异性条带,融合菌株SR002、SR003菌丝生物量是亲本SA04的3倍。SR005菌株合成胞外多糖速率最快,但SR002胞外多糖产量最高,较亲本SA02增加到1.8倍。融合菌株SR005在培养后期发酵液中酯酶活性最高。SR002、SR003两菌株亲缘关系极为相近。结论 筛选得到的SR002菌株经进一步遗传稳定性验证后可用于以获得生物量、胞外多糖为目的的液体发酵培养。     

几丁质酶产生菌发酵条件初步研究

本文研究了一株几丁质酶高产菌株--地衣芽孢杆菌JDZ－3 (Bacillus licheniformis JDZ－3)产几丁质酶的发酵条件。在影响几丁质酶产生的主要因素中,培养基的最佳初始pH为7.0,几丁质酶的最佳碳源为胶体几丁质,最佳氮源为酵母膏,最佳金属离子为Mg2+,最适的发酵温度为30℃。在单因素优化法的基础上,利用正交实验确定了该菌株产几丁质酶发酵培养基的三大营养元素的组成为：胶体几丁质0.2%,酵母膏0.6%,MgSO4?H2O 0.1%。利用此培养基于30℃发酵72h,其上清液中的几丁质酶的活力可达2.76U/mL。