苏云金芽胞杆菌及其在蜂病防治中的应用

本文阐述了有关苏云金芽胞杆菌(Bacillusthuringiensis,简称Bt)在传统农业害虫防治中的应用以及对大蜡螟的毒杀作用,为蜜蜂病虫害防治领域带来了新的曙光。     

苏云金芽胞杆菌晶体蛋白对羊捻转血矛线虫成虫的作用

将羊经丙硫咪唑驱虫后隔离饲养,人工感染捻转血矛线虫第３期幼虫,当第２６天从粪便中查出捻转血矛线虫虫卵后,由颈静脉、肌肉注射及经口灌服苏云金芽胞杆菌（Ｂ.t）伴胞晶体蛋白,每日１次,连续３次。以后隔日从羊直肠内采粪,用饱和盐水漂浮法查虫卵,并计算ＥＰＧ（每克粪便中虫卵数）。静注和肌注晶体蛋白后的羊,分别于注射后１周、２周、４周扑杀,口服和对照组羊４周后扑杀,从皱胃和小肠内查虫。结果表明,经静注（晶体蛋     

苏云金芽胞杆菌晶体毒素引发的日本血吸虫超微结构改变

对人工感染日本血吸虫尾蚴45d的家兔作主动脉灌注冲虫，获得的成虫经Earle’s液洗涤，加入细胞培养板内，用含10％牛血清的RPMI-1640培养液于37C、5％CO2培养箱中培养，将30mg／L的苏云金杆菌BtYBT-1532和HD-1毒素蛋白分别加入各孔中，取培养1、2、4、8、24、48h的虫体，制作超薄切片进行透射电镜观察。结果发现：HD-1不引起血吸虫体壁超微结构的变化。YBT-1532毒素则引发血吸虫成虫表皮的各种变化，包括基质空泡化，褶嵴肿胀粘连，基膜和环肌肿胀，杆状分泌小体和指环体减少，感觉结构坏死，环肌溶解，体壁细胞胞质内细胞器溶解坏死，纵肌肿胀，褶嵴破渍；雌虫肠壁基质脂滴增多，出现坏死区域。上述超微结构的改变均随毒素感作时间的延续而渐进增重。     

甘露寡糖对枯草芽孢杆菌在肉鸡肠道内的排出及肠道菌群的影响

研究旨在考察甘露寡糖(MOS)对枯草芽孢杆菌在AA肉鸡肠道内的排出及其对肠道微生物菌群的影响。试验选取180羽1日龄AA肉鸡,随机分为3组,每组6个重复。对照组灌喂无菌水,处理组灌喂芽孢液或含0.2%MOS的芽孢液各1.0 mL;每12 h采集粪样测定芽孢数,并在芽孢排完后采用变性梯度凝胶电泳(DGGE)测定粪甘露寡糖样中的微生物群落结构;涂布平板法测定肉鸡盲肠内大肠杆菌、总好氧菌和乳酸杆菌的数量。结果表明:与灌喂芽孢组相比,添加MOS 72 h后,能显著提高肉鸡盲肠内乳酸杆菌(P<0.05),降低总需氧菌和大肠杆菌数量(P<0.05),但对排出的总芽孢数无影响。PCR-DGGE的分析表明,MOS对细菌群落的多样性无影响(P>0.05)。提示添加0.2%MOS不影响芽孢杆菌在肉鸡上发挥作用,并能提高其益生效果。     

苏云金芽胞杆菌伴胞晶体毒素对小鼠体内猪蛔虫三期幼虫的作用及其免疫组织化学定位

将培养好的感染性猪蛔虫卵以每只5×103个虫卵感染小鼠,于次日以不同方式(灌胃、肌肉注射、静脉注射和腹腔注射)注入苏云金芽胞杆菌伴胞晶体蛋白(insecticidal crystal proteins,Icps),对照组静脉注射BSA(小牛血清白蛋白),每只0.5mL,连续3d。小鼠于第6天剖杀,肝脏分离幼虫,计算减虫率。取肝脏,以4%多聚甲醛固定48h,制作石蜡切片,应用免疫组织化学SABC法定位蛔虫幼虫体内的Icps。研究结果显示,静脉注射晶体蛋白毒素效果最好,减虫率达到72.7%;肌肉注射、灌胃、腹腔注射效果次之,分别为19.1%、14.6%、14.36%。免疫组织化学研究显示,Icps结合到虫体的体表及肠道。     

苏云金芽胞杆菌晶体毒素对体外培养的日本血吸虫童虫的作用

将感染日本血吸虫的钉螺常规逸蚴，经注射器推压机械断尾获得的童虫，加入内含１０％兔血清的ＲＰＭＩ－１６４０培养液后，置于单克隆培养板内，以苏云金芽胞杆菌（菌株ＹＢＴ－１９５５）制得的伴胞晶体毒素，以不同的浓度加入以上各孔中于３７℃，５％ＣＯ２培养箱内培养。培养１２ｈ后发现童虫活动力减弱，有些已经死亡；２４ｈ后，随着加入伴胞晶体毒素浓度的增加，童虫死亡率也相应增加，呈正相关（ｒ＝０．８９７）。经毒素蛋白含量为４０ｍｇ／Ｌ处理的童虫，２４ｈ后死亡率为１００％，ＬＤ５０为１５．９５μｇ（１ｍＬ）。     

涂林吉（苏云金）芽胞杆菌伴胞晶体毒素对捻转血矛线虫虫卵的致死作用

从感染捻转血矛线虫山羊的直肠内取粪便，分离出虫卵，置单克隆板孔中，再往各孔中加入系列浓度的涂林吉（苏云金）芽胞杆菌（ＹＢＴ－１９５３）伴胞晶体毒素溶液，置２５℃培养２４ｈ。结果表明，当伴胞晶体毒素总蛋白为１２０μｇ／ｍＬ时，虫卵死亡率为９９．４％，０．６％未死的虫卵孵出的第１期幼虫也因毒素的作用而全部死亡。本研究表明，涂林吉芽胞杆菌（ＹＢＴ－１９５３）伴胞晶体蛋白对捻转血矛线虫虫卵具有较强的毒力。     

木聚糖酶对肉仔鸡后肠道微生物的影响

主要研究了小麦基础口粮添加木聚糖酶对肉仔鸡后肠道微生物的影响.将120只7日龄肉仔鸡分成2组,日粮分别添加0,0.1%木聚糖酶,饲喂至21日龄,研究木聚糖酶对肉仔鸡后肠道菌群数量变化的影响.结果表明,加酶未使同肠和盲肠乳酸杆菌、双歧杆菌和大肠杆菌数量发生显著变化.利用变性梯度凝胶电泳技术研究了木聚糖酶对肉仔鸡后肠细菌群体的影响.结果表明,加酶组回肠和盲肠的图谱比对照组条带相对较多,但差异不显著;组内个体间的图谱相似性比组问的相似性相对较大.木聚糖酶影响肉仔鸡后肠微生物数量和种群的作用效果不明显.     

Effects of alfalfa meal on the intestinal microbial diversity and immunity of growing ducks

This study was conducted to investigate the effects of alfalfa meal diets on the intestinal microbial diversity and immunity of growing egg‐type ducks. A total of 128 healthy 7‐week‐old female egg‐type Shaoxing ducks were selected and randomly assigned into four dietary treatments: 0%, 3%, 6% and 9% alfalfa meal for 8 weeks. Each treatment consisted of four replicates of eight ducks each. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR‐DGGE) was used to characterize the microbiota. The results showed that the DGGE fingerprints of the V6–V8 fragments of the 16S rRNA from the caeca and faeces of ducks fed 3%, 6% and 9% alfalfa meal had significantly higher microbiota species richness than those fed 0% alfalfa meal (p < 0.05). The Shannon–Weiner index of the microbiota from the caeca and faeces of ducks fed 3%, 6% and 9% alfalfa meal was significantly higher than those fed 0% alfalfa meal (p < 0.05). Molecular analysis of the caecal and faecal DNA extracts showed that the alfalfa meal diet promotes the intestinal microbial diversity, as indicated by their higher species richness and Shannon–Weiner index. However, the groups did not significantly differ in terms of average daily gain, feed intake and gain‐to‐feed ratio (p > 0.05), and the 3–9% alfalfa meal did not affect the growth performance of the growing egg‐type ducks. The proliferation of T and B lymphocytes was significantly greater (p < 0.05) in the groups supplemented with 3%, 6% and 9% of alfalfa meal than the unsupplemented control group, and alfalfa meal promoted the lymphocytes proliferation of the growing egg‐type ducks. Dietary alfalfa meal supplementation increases intestinal microbial community diversity and improves of the immune response growing egg‐type ducks.     

Lactobacillus hayakitensis, L. equigenerosi and L. equi, predominant lactobacilli in the intestinal flora of healthy thoroughbreds

To detect the predominant lactobacilli in the intestinal flora of healthy thoroughbreds, we isolated lactobacilli from the feces of nine thoroughbreds (five males and four females; 0–15-year-old). The isolated lactobacilli comprise 17 species (37 strains), and they were classified into five groups: Lactobacillus salivarius (6 species), L. reuteri (6 species), Lactobacillus delbrueckii (3 species), L. buchneri (1 species) and L. vitulinus (1 species). On the basis of 16S rRNA gene sequences, we identified 3 other phylogenetic relatives belonging to the genus Lactobacillus . These results suggest that the intestinal flora of thoroughbreds may comprise many species of the genus Lactobacillus . Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analyses of the 340-bp fragments of the 16S rRNA genes from the same nine fecal samples showed that L. hayakitensis , L. equigenerosi and L. equi are contained in all the samples, suggesting that these species are predominant lactobacilli in the intestinal flora of thoroughbreds.     

变性梯度凝胶电泳技术及其在动物肠道菌群研究中的应用

变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)技术是一种新型的用于检测核酸变异和点突变的电泳方法,主要根据突变型和野生型核酸序列的不同而导致其变性浓度的差异,从而利用变性梯度胶进行分离,可用于肠道菌群结构多样性和种群动态变化的研究。文章对DGGE技术的原理、在肠道菌群多样性和动态性的应用、局限性及发展前景及上综述。     

PCR-DGGE实验技术在畜牧科学研究中的应用

本文综述了以变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)为主要手段结合聚合酶链式反应(polymerase chain reaction,PCR)实验技术的基本原理、主要实验流程,优缺点以及它在畜禽肠道等微生物的群落结构和多样性研究的最新动态。     

Ammonia‐oxidizing Archaea in laboratory‐scale activated sludge systems for wastewater of low‐ or high‐ammonium concentration

Ammonia‐oxidizing bacteria (AOB) is known as ammonia‐oxidizer in wastewater treatment systems. However, ammonia‐oxidizing Archaea (AOA) is found from various environments, including wastewater treatment systems. In this study, to investigate the relationships between AOA population and ammonia concentration, AOA was monitored in two laboratory‐scale reactors treating artificial wastewater of different ammonium concentrations by denaturing gradient gel electrophoresis targeting ammonia monooxygenase genes. At day 60 of the operation, AOA populations dominant in each reactor differed, suggesting the importance of influent ammonia concentration in dominant AOA selection.     

Changes in the bacterial community and composition of fermentation products during ensiling of wilted Italian ryegrass and wilted guinea grass silages

To gain further insights into temperate and tropical grass ensiling, fermentation products and bacterial communities were examined at both the initial and late stages of ensiling of wilted Italian ryegrass and wilted guinea grass silages. 2,3‐Butanediol and ethanol fermentation were observed in wilted Italian ryegrass silage. Enterobacteria such as Rahnella sp. and Enterobacter sp. may have been involved in fermentation; however, alcohol production was intensified after the silage enterobacterial community overwhelmed the pre‐ensiled enterobacterial community. Pediococcus spp. appeared in silage stored for 4 months, when a significant increase in lactic acid content was seen compared with that at 2 months. Prolonged storage enhanced acetic acid fermentation in wilted guinea grass silage. The disappearance of Enterococcus sulfureus and appearance of Lactobacillus plantarum may have been associated with the increased acetic acid content. Although many species of enterobacteria were found in common between the pre‐ensiled crop and silages of Italian ryegrass and guinea grass, marked differences were seen in the type of fermentation from the initial stages. These results indicate that the bacterial community of pre‐ensiled crops may be immediately replaced by one that is adapted to ensiling environments, although metabolic changes may continue over the course of ensiling.     

动物园动物粪便中苏云金芽孢杆菌调查

为了寻求新的苏云金芽孢杆菌(Bt)菌株,对福建省福州市动物园和三明市动物园41种动物(其中哺乳动物33种、禽类8种)粪便中Bt进行调查。从50个粪便样品中共分离到253株芽孢杆菌,其中有15株含有晶体蛋白,确定为Bt,Bt分离率为30%。在所分离的粪便样品中,采自草食动物粪便的Bt分离率最高,达35.5%;其次是杂食动物粪便的Bt分离率为25%,肉食性动物粪便的Bt分离率最低,仅18.2%。结果表明:植物源日粮动物粪便中的Bt含量较高。     

Influences of quorum‐quenching probiotic bacteria on the gut microbial community and immune function in weaning pigs

The aim of this study is to investigate the dynamic gut microbial diversity in weaning swine after administering feed supplemented with probiotic bacteria that specifically inhibit the activity of quorum molecules. Initially, the universal quorum molecule autoinducer‐2 (AI‐2) bioassay results indicated that AI‐2 activity was profoundly inhibited in enterohemorrhagic Escherichia coli (EHEC) O157:H7 in the presence of Lactobacillus acidophilus strain 30SC cell extract, although the growth of EHEC was not affected. Based on plate counting results, bacterial community analysis revealed a specific reduction in coliforms compared to the control, whereas the population of lactobacilli increased in weaning swine in in vivo trials. Supplementation with L. acidophilus strain 30SC did not affect the counts of other communities, such as total aerobes and yeast/mold. In addition, PCR‐denaturing gradient gel electrophoresis analysis showed a significant difference in the 16S rRNA gene products after administering L. acidophilus strain 30SC. Selected bands were sequenced, and most of them were identified as uncultured bacterium clones or a Lactobacillus‐ and Bifidobacterium‐specific community. Therefore, our results indicate that quorum‐quenching probiotic bacteria can significantly modulate the gut microbiota of swine and these beneficial effects can contribute to the improvement of performance and health in the gastrointestinal tract of weaning pigs.