我国南方红壤矿山复垦土壤的微生物特征研究

通过对浙江哩铺铜矿废弃地复垦土壤的微生物特征研究表明 :与对照土壤相比 ,矿区复垦土壤微生物区系发生明显改变 ,微生物总数下降了 6 8.4 %～ 80 .3 2 %。微生物特征发生了显著的改变 ,微生物基础呼吸作用增强 ,但微生物生物量却显著降低 ,微生物生理生态参数 Cmic/Corg、q CO2 值明显升高。矿区土壤在重金属胁迫下 ,削弱了土壤中 C,N营养元素循环速率和能量流动     

菠萝-甘蔗轮作制度对甘蔗生长及土壤生态的影响

研究菠萝-甘蔗轮作制对甘蔗生长及土壤生态的影响结果表明,菠萝-甘蔗轮作甘蔗产量和糖度均高于甘蔗-甘蔗连作;与连作田相比轮作田可改善土壤通气性和蓄水能力,加速土壤速效养分的释放,增强土壤酶活性和增加土壤微生物总量;有益的氨化细菌和硝化细菌成倍增加,而无益的厌氧性细菌、反硝化细菌则受抑制。     

玉米皮和大豆皮组合替代玉米和玉米秸秆对育肥羊生长性能和瘤胃代谢的影响

本试验旨在研究玉米皮和大豆皮组合代替饲粮中部分玉米和玉米秸秆对育肥羊生长性能、瘤胃发酵和微生物区系的影响。试验选用36只健康、(120±11)日龄和体重[(22.20±0.92)kg]相近的杜泊×小尾寒羊杂交公羔为试验动物,随机分为3组,每组12只,分别饲喂3种不同的饲粮:1)0玉米皮+0大豆皮(对照组);2)9%玉米皮+9%大豆皮(18MIX组);3)17%玉米皮+17%大豆皮(34MIX组)。试验期共85 d,其中预试期15 d。结果表明:1)34MIX组的末体重和干物质采食量均显著高于对照组(P<0.05),与18MIX组差异不显著(P>0.05);34MIX组和18MIX组的平均日增重和饲料转化率显著高于对照组(P<0.05),34MIX组的平均日增重最高。2)34MIX组的瘤胃乙酸和总挥发性脂肪酸浓度显著高于对照组(P<0.05),而瘤胃氨态氮浓度显著低于对照组(P<0.05),与18MIX组差异不显著(P>0.05)。3)18MIX组和34MIX组瘤胃液中羟甲基纤维素酶和木聚糖酶活性均显著高于对照组(P<0.05)。4)18MIX组和34MIX组瘤胃中黄色瘤胃球菌、白色瘤胃球菌、产琥珀酸丝状杆菌和溶纤维丁酸弧菌的数量显著高于对照组(P<0.05)。综上,利用玉米皮和大豆皮组合代替饲粮中一定比例的玉米和玉米秸秆有利于育肥羊生长和瘤胃代谢效率。     

干酪乳杆菌对北京黑猪育肥阶段肠道消化物菌群组成及乳酸、短链脂肪酸和长链脂肪酸含量的影响

本试验探讨了在饲粮中添加干酪乳杆菌对北京黑猪育肥阶段肠道消化物菌群组成及乳酸、短链脂肪酸和长链脂肪酸含量的影响。选择体重为(62.77±0.59)kg的北京黑猪120头,随机分成2组,分别为对照组和干酪乳杆菌组,每组5个重复,每个重复12头(阉公猪与母猪各占1/2)。对照组饲喂基础饲粮(不添加抗生素和干酪乳杆菌),干酪乳杆菌组在基础饲粮中添加干酪乳杆菌冻干制剂(每千克饲粮中有效活菌数为2.0×10^9 CFU)。在试验猪平均体重为92 kg时,选择20头猪进行屠宰,采集空肠和结肠中的消化物,用于分析菌群组成及乳酸、短链脂肪酸和长链脂肪酸含量。结果表明:1)与对照组相比,饲粮中添加干酪乳杆菌显著提高了空肠中厚壁菌门和链球菌属的相对丰度(P<0.05),显著降低了变形菌门、Terrisporobacter和埃希氏菌属-志贺氏菌属的相对丰度(P<0.05);显著提高了结肠中拟杆菌门、乳杆菌属和未标记拟杆菌目_S24-7_群的相对丰度(P<0.05),显著降低了链球菌属的相对丰度(P<0.05)。2)与对照组相比,干酪乳杆菌组结肠中乳酸含量显著降低(P<0.05),丁酸含量显著升高(P<0.05)。3)与对照组相比,饲粮中添加干酪乳杆菌显著降低了空肠中山嵛酸和顺-15-二十四碳一烯酸含量(P<0.05),显著提高了二十二碳六烯酸和ω-3多不饱和脂肪酸含量(P<0.05);显著降低了结肠中棕榈油酸和花生四烯酸含量(P<0.05)。综上所述,在北京黑猪育肥阶段饲粮中添加干酪乳杆菌,减少了空肠中埃希氏菌属-志贺氏菌属的相对丰度,增加了结肠中乳杆菌属的相对丰度;降低了结肠中乳酸的含量,提高了丁酸的含量;提高了空肠中二十二碳六烯酸的含量,降低了结肠中花生四烯酸的含量。肠道内的这些变化有利于猪群健康和生长性能的提高。     

半胱胺螯合锌对育肥猪免疫性能、抗氧化能力、血清生化指标及肠道微生物的影响

本试验旨在研究饲粮中不同添加量的半胱胺螯合锌(Zn-CS)对育肥猪免疫性能、抗氧化能力、血清生化指标及肠道微生物的影响。选取90头体重为(64.67±1.15)kg的健康育肥猪,随机分为5组,每组3个重复,每个重复(圈)6头。对照组饲喂基础饲粮,试验组分为Ⅰ、Ⅱ、Ⅲ、Ⅳ组,分别饲喂在基础饲粮中添加60、90、120、150 mg/kg Zn-CS的试验饲粮。结果表明:1)与对照组相比,Ⅰ、Ⅱ组血清免疫球蛋白A(IgA)含量显著提高(P<0.05)。2)与对照组相比,Ⅲ、Ⅳ组血清丙二醛含量显著降低(P<0.05),Ⅱ、Ⅲ、Ⅳ组血清总抗氧化能力显著提高(P<0.05)。3)与对照组相比,Ⅱ组血清生长激素含量显著提高(P<0.05),Ⅱ组血清生长抑素含量显著降低(P<0.05),Ⅱ、Ⅲ、Ⅳ组血清胰岛素含量显著提高(P<0.05)。4)各组在门水平上相对丰度超过1%的优势菌门有厚壁菌门、变形菌门、拟杆菌门,各组在属水平上相对丰度超过1%的优势菌属有梭菌属、肠杆菌属、Romboutsia、Turicibacter、Terrisporobacter、放线菌属。由此可见,饲粮中添加Zn-CS能够提高育肥猪免疫性能与抗氧化能力。在本试验条件下,建议Zn-CS在育肥猪饲粮中的适宜添加量为120 mg/kg。     

健康与腹泻仔猪肠道菌群多样性差异分析

探讨腹泻对仔猪肠道菌群变化的影响,以健康仔猪和腹泻仔猪新鲜粪便为研究对象,利用传统平板计数的方法和PCR-DGGE技术比较了不同日龄健康和腹泻仔猪肠道菌群数量差异和菌群结构变化。结果表明不同日龄的仔猪粪便样品中的细菌总数,乳酸杆菌数腹泻组较健康组均有下降,其中21日龄健康与腹泻仔猪的细菌总数差异极显著,乳酸杆菌数差异显著;DGGE指纹图谱聚类分析表明,与其它日龄组相比21日龄健康组与腹泻组样品肠道总细菌和乳酸杆菌菌群结构均相似度最低。说明仔猪发生腹泻引起的细菌数量变化与菌群结构复杂程度变化可能存在一定的相关性。     

致乏库蚊体内菌群结构分析

采用PCR–DGGE技术,分析致乏库蚊雌成虫的带菌情况。无菌条件下研磨体表消毒的致乏库蚊雌成虫,提取细菌总DNA,以通用引物扩增细菌16S r DNA V3区,经DGGE电泳、克隆、测序、比对,确定该蚊体内的优势菌。结果表明,致乏库蚊雌成虫携带的优势菌共有6种,其中1种为派毕梯斯沃巴契亚体(Wolbachia pipientis),另外5种尚未被鉴定,分别隶属于假单胞菌属(Pseudomonas sp.)、埃希氏杆菌属(Escherichia sp.)、沃尔巴克氏体属(Wolbachia sp.)和α–变形纲、γ–变形纲某未知种属。     

Clinical and aetiological aspects of a summer enteritic syndrome associated with the sporulating segmented filamentous bacterium 'Candidatus Arthromitus' in farmed rainbow trout, Oncorhynchus mykiss (Walbaum)

An enteritic syndrome affecting farmed rainbow trout and occurring predominantly in summer has recently been described and related to the massive accumulation of a segmented filamentous bacterium (SFB), ‘Candidatus Arthromitus’, in the digestive tract of fish. Details of the clinical manifestations, the characteristics of the bacterium and the possible aetiology of the disease are presented in this paper. No other bacterial pathogen than ‘Candidatus Arthromitus’ was characterized in trout undergoing the enteritic syndrome. From clinical and histopathological observations, a toxin or toxic product accumulation was suspected in affected trout, and could account for the massive destruction of the intestinal mucosa. However, the origin and aetiological role of the SFB could not be clearly elucidated, although most of the filaments appeared to beviable and to produce and release strings of endospores in the lumen of the gut. The organism could not be cultured in the conditions tested, shared several morphological and structural characteristics with related bacteria described in the intestinal microflora of different vertebrate species, but no attachment structure was definitively recognized. All attempts to detect similar SFB in the fish diet orin the environment of affected fish farms were unsuccessful. It is unclear whether this organism represents a normal and not previously detected inhabitant of the intestine of trout stressed after environmental perturbation, or whether it results directly from external sources of contamination.     

Comparison of conventional and molecular techniques to investigate the intestinal microflora of rainbow trout (Oncorhynchus mykiss)

The concept of the use of probiotic organisms or prebiotic compounds to modify the fish gut microflora is becoming a popular topic for investigation. A major flaw in many such studies is a failure to consider fully the nature of the established microflora, which is to be modified pre-, or probiotically. Since it is widely accepted that a large proportion of bacteria are non-culturable, the use of conventional bacteriological (culture) techniques alone to investigate fish intestinal microflora may be expected to bias results. We report a study designed to investigate the normal intestinal microflora of rainbow trout (Oncorhynchus mykiss) using both conventional bacteriological and molecular methods.Over an 18 month period, the intestinal microflora of a single population of laboratory-raised rainbow trout was investigated. Bacteria isolated using bacteriological techniques were identified using the BiOLOG system and 16S rRNA gene sequencing. Dominant bacteria consistently were Aeromonas sp. and Carnobacterium piscicola, demonstrating that the microflora is stable in fish kept in defined conditions. Restriction Fragment Length Polymorphism (RFLP) and 16S rRNA gene sequence analysis was used to investigate anaerobic and non-culturable bacteria. An obligate anaerobe, Clostridium gasigenes, was shown to be among the dominating intestinal microflora.     

花生连作障碍发生机理研究进展

连作导致花生产量和品质下降,严重影响了花生持续生产。本文结合20年花生长期定位试验研究,从土壤理化性质恶化、化感自毒作用和微生物区系失衡3个方面系统地综述了花生连作障碍的发生机理,认为花生根际微生态系统综合功能失调是造成花生连作障碍的主要原因,并分别就化感作用、根际分泌物与根际微生物的关系、根际微生物与连作障碍的关系和多因子综合考虑等角度对该领域未来的研究方向进行了展望。