Bacteriological quality of raw materials used in Finnish mink feed.

Mink feed raw materials were analyzed for total bacterial count, the number of faecal streptococci, the coliform count, the number of haemolytic bacteria and the number of sulphite reducing bacteria. The investigation comprised samples from the following raw materials: four slaughter-house offal products, preserved and unpreserved slaughter blood, Baltic herring, cod filletting offal, fish silage, blood meal, fish meal, meat-bone meal, protein concentrate, brewer’s yeast and cereal feed.The slaughter-house offals and unpreserved slaughter blood had the poorest quality, in terms of all the bacterial types for which the samples were analyzed. There were statistically significant differences in bacterial contents between slaughter-house offals from different sources. The preserved slaughter blood had significantly lower bacterial contents as compared to the unpreserved slaughter blood. Single samples of the cod filletting offal, Baltic herring and the blood meal had relatively high total bacterial counts, but the specified mean bacterial counts were relatively low. The bacterial counts for the rest of the investigated raw materials were relatively low.     

一种治疗奶牛阴道炎症微生态制剂的临床药效学研究

为检验约氏乳杆菌SQ0048菌株所制备的微生态制剂对临床型奶牛阴道炎症的治疗作用,将其应用于患有阴道炎的病牛体内,利用临床兽医学方法观察给药前后患牛的临床症状,采用变性梯度凝胶电泳法检测给药前后患牛阴道内的微生物菌群种属,使用酶联免疫吸附技术检测给药前后患牛血清内细胞因子分泌量。结果显示,此微生态制剂不仅可以缓解临床奶牛阴道炎性症状,提高发情率及受胎率,还可以减少或杀灭阴道内的利氏卟啉单胞菌、铜绿假单胞菌、化脓隐秘杆菌及链球菌等,增加约氏乳杆菌SQ0048菌株及谷氨酸棒状杆菌的数量,改善阴道微生态环境,维持阴道的微生态平衡;同时给药后患牛血清中IL-1β、IL-6、IFN-α、TNF-α分泌量显著低于给药前,而IL-10分泌量则显著高于给药前,具有一定抑制炎症的生物学功能。     

乳酸菌代谢研究进展

乳酸菌代谢研究已进入一个新的时代,本文主要阐述目前乳酸菌在糖代谢、柠檬酸代谢及蛋白质代谢等方面的研究,以及基于下一代测序技术的基因组学、比较基因组学和宏基因组学等技术手段在乳酸菌代谢研究中的应用,旨在为现代乳酸菌代谢研究提供理论支持。     

救必应水提取物对产ESBLs细菌的抑菌机理研究

为了探讨救必应水提取物的抑菌作用及抑菌机理,采用2倍微量稀释法和琼脂平板稀释培养计数法,测定救必应水提取物对产ESBLs(extended spectrum β-lactamases)细菌的最小抑菌浓度(minimal inhibitory concentration,MIC)和最小杀菌浓度(minimal bactericidal concentration,MBC),通过对细菌生长曲线、细菌超微结构、细胞壁和细胞膜通透性变化试验、核酸合成抑制试验研究救必应水提取物的抑菌机理。结果表明,与不添加提取物的对照组相比,救必应水提取物能够影响细菌的生长规律,使细菌破损严重,细胞壁和细胞膜通透性增加,细胞质外渗,菌液中AKP含量、可溶性蛋白含量增多、大肠杆菌DNA荧光强度明显减弱。研究表明,救必应水提取物的抑菌机理是通过细菌细胞壁和细胞膜通透性的变化,抑制细菌核酸的合成实现的。     

Effect of hay type on cecal and fecal microbiome and fermentation parameters in horses

The effect of hay type on the microbiome of the equine gastrointestinal tract is relatively unexplored. Our objective was to characterize the cecal and fecal microbiome of mature horses consuming alfalfa or Smooth Bromegrass (brome) hay. Six cecally cannulated horses were used in a split-plot design run as a crossover in two periods. The whole plot treatment was ad libitum access to brome or alfalfa hay fed over two 21-d acclimation periods with subplots of sampling location (cecum and rectum) and sampling hour. Each acclimation period was followed by a 24-h collection period where cecal and fecal samples were collected every 3 h for analysis of pH and volatile fatty acids (VFA). Fecal and cecal samples were pooled and sent to a commercial lab (MR DNA, Shallowater, TX) for the amplification of the V4 region of the 16S rRNA gene and sequenced using Illumina HiSeq. The main effects of hay on VFA, pH, and taxonomic abundances were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of hay, hour, location, period, and all possible interactions and random effect of horse. Alpha and beta diversities were analyzed using the R Dame package. Horses fed alfalfa had greater fecal than cecal pH (P ≤ 0.05), whereas horses fed brome had greater cecal than fecal pH (P ≤ 0.05). Regardless of hay type, total VFA concentrations were greater (P ≤ 0.05) in the cecum than in feces, and alfalfa resulted in greater (P ≤ 0.05) VFA concentrations than brome in both sampling locations. Alpha diversity was greater (P ≤ 0.05) in fecal compared with cecal samples. Microbial community structure within each sampling location and hay type differed from one another (P ≤ 0.05). Bacteroidetes were greater (P ≤ 0.05) in the cecum compared with the rectum, regardless of hay type. Firmicutes and Firmicutes:Bacteroidetes were greater (P ≤ 0.05) in the feces compared with cecal samples of alfalfa-fed horses. In all, fermentation parameters and bacterial abundances were impacted by hay type and sampling location in the hindgut.     

细菌生物被膜与抗生素耐药机制研究进展

细菌引发的感染已成为感染性疾病的主要原因之一,具有耐药性和难治性的特点,而且还可以对抗机体的免疫清除作用,对人类和动物的健康造成很大的危害,也给人们生活的其他方面带来了越来越严重的影响,引起了基础和临床研究的极大关注。但是细菌生物被膜对抗生素的耐药机制目前还不十分清楚,现对近年来细菌生物被膜对抗生素耐药形成的几种可能机制进行综述。     

我国部分地区牛支原体肺炎和关节炎的病原体诊断

重庆等4省市从外省引进的肉牛群发生以严重肺炎和关节炎为主要表现的疾病。该病的病变主要集中于肺脏,其组织学变化主要是间质增生,纤维素渗出,干酪样坏死,淋巴细胞、嗜中性粒细胞和单核细胞浸润。PCR检测病牛肺脏显示牛支原体阳性,而丝状支原体丝状亚种、牛分支杆菌和多杀性巴氏杆菌为阴性。从肺等组织中分离到牛支原体以及大肠杆菌、沙门氏菌、链球菌、葡萄球菌和烟曲霉,没有分离到巴氏杆菌。结果显示本病是以牛支原体感染为主引起的牛支原体肺炎和关节炎,长途运输等应激因素是该病突发的重要诱因,其他细菌和/或真菌继发感染加重了病情。     

低聚糖对雏鸡大肠粪便NH3-N含量及肠道菌群的影响

试验选取1日龄罗曼蛋公雏250只，随机分为5组，试验组饲料或饮水中分别添加海藻糖(500mg／kg)、海藻胶(600mg／kg)、大豆寡糖(500mg／kg)、圆葱寡糖(500mg/d)。结果表明，四种低聚糖均可促进肠道乳酸菌及双歧杆菌的生长繁殖，对魏氏梭菌的生长呈现抑制作用。海藻糖、海藻胶对降低大肠粪便NH3—N含量效果不显著(P＞0．05)，而大豆寡糖效果显著(P＜0．05)，圆葱寡糖效果极显著(P＜0.01)。     

对禾草源同型发酵和/或异型发酵乳酸菌发酵无芒雀麦青贮有氧稳定性的评价

本研究旨在评价禾草源同型发酵和/或异型发酵乳酸菌发酵对无芒雀麦青贮有氧稳定性的作用效果。将从禾本科牧草上分离筛选出的2株同型发酵植物乳杆菌(Lactobacillus plantarum)和蒙氏肠球菌(Enterococcus mundtti)及1株异型发酵布氏乳杆菌(Lactobacillus buchneri)制成发酵剂。选用开花期无芒雀麦,刈割切段至2~3 cm,根据所喷发酵剂菌株的不同,分为4个处理:1)对照处理(con处理),喷洒无菌去离子水;2)异型发酵处理(he处理),喷洒布氏乳杆菌液;3)同型发酵处理(ho处理),喷洒植物乳杆菌和蒙氏肠球菌混合液(2种菌1∶1混合);4)同型发酵+异型发酵处理(he+ho处理),喷洒布氏乳杆菌、植物乳杆菌和蒙氏肠球菌混合液(3种菌1∶1∶1混合)。各处理喷洒量均为10 m L/kg鲜牧草,喷洒总菌数约为5×105CFU/g鲜牧草,每个处理设5个重复。实验室常温发酵60 d后开封,通过测定无芒雀麦青贮营养成分、菌群数量及中心温度变化评价其有氧稳定性。结果显示:经60 d青贮发酵后,4个处理的p H均较青贮前显著降低(P0.05),所有处理发酵效果均较好(p H≤4.3),尤以ho处理效果最优。而在有氧暴露试验期间,con和ho处理的p H迅速增加,至第8天时达到7以上;he+ho处理p H增加幅度略低于con和ho处理,其p H至第8天时为6.3,显著低于con和ho处理(P0.05);he处理p H增加非常缓慢,至第8天时仅为4.4,显著低于其他处理(P0.05)。经60 d青贮发酵后,可溶性碳水化合物(WSC)含量以ho处理最高,显著高于其他处理(P0.05);con处理最低,显著低于其他处理(P0.05)。而在有氧暴露试验期间,WSC含量在ho处理中迅速降低,在he处理中缓慢降低;至第8天时,WSC含量以he处理最高,he+ho处理显著低于前者(P0.05),而con和ho处理则显著低于he和he+ho处理(P0.05)。青贮发酵后霉菌数量明显受到抑制,且以单独添加异型发酵乳酸菌和混合添加同型发酵和异型发酵乳酸菌时抑制效果较优,这2个处理均未检出霉菌,且he+ho处理在有氧暴露至第5天时仍未检出霉菌,he处理在有氧暴露至第8天时仍未检出霉菌。在有氧暴露第3和5天时,he和he+ho处理酵母菌数量显著低于con、ho处理(P0.05)。在有氧暴露第8天时,he+ho与he处理的乳酸、乙酸浓度均显著高于另2个处理(P0.05)。he、he+ho、con和ho处理的有氧稳定性依次降低,分别为194、126、62和58 h。综合评价结果得出:布氏乳杆菌单独或与同型发酵乳酸菌蒙氏肠球菌和植物乳杆菌联合接种可有效抑制无芒雀麦青贮的有氧腐败,保证无芒雀麦青贮有氧暴露期间品质的稳定,且前者更有效;接种同型发酵乳酸菌蒙氏肠球菌和植物乳杆菌未能在提高无芒雀麦青贮有氧稳定性方面表现出积极的作用。     

转录组解析白三叶根际溶磷菌株RW8的解磷机制

采用转录组测序的方法分析了白三叶根际溶磷菌RW8在含有难溶磷(A组)、可溶磷(B组)与无磷(C组)培养条件下差异基因表达。以可溶磷为对照,在难溶磷条件下,分别检测到4782个基因在RW8中上调表达,447个基因下调表达;在无磷组中,共检测到3630个基因上调表达,209个基因下调表达。GO基因注释发现RW8在A组和C组中的差异基因聚类基本相同。生物学过程主要聚类在代谢过程、细胞过程、单细胞过程、刺激应答、定位以及生物反应调节;细胞组分主要聚类在细胞组分、细胞膜、膜组分与高分子配合体等;分子功能主要聚类在催化活性、结合功能与转运功能。代谢途径分析发现2-α-氧代羧、α-亚麻酸、五碳二元酸、脂肪酸、甘氨酸-丝氨酸-蛋氨酸以及缬氨酸-亮氨酸-异亮氨酸等代谢途径的基因显著被富集。挑选10个差异基因并用荧光定量检测其在A、B、C 3种不同培养条件下的基因表达,发现所有挑选基因的表达变化与转录组结果变化趋势相同。液相色谱检测有机酸组成及含量,发现在A组和C组中乳酸、琥珀酸与柠檬酸显著高于B组,富马酸与苹果酸的含量在C组中显著升高, A组与B组差异不显著;α-酮戊二酸的含量在A组中显著增高, B组和C组差异不显著。