Microbial protein formation of different carbohydrates in vitro

The aim of this study was to investigate the microbial protein yield of different pure carbohydrates to contribute to a more precise prediction of the microbial protein formed in the rumen. In a first experiment, sucrose, wheat starch, microcrystalline cellulose and citrus pectin were incubated for 8 and 24 hr in the modified Hohenheim gas test (HGT) system (3 runs × 2 syringes) including gas production, ammonia and short‐chain fatty acid concentration measurements. Ammonia values were used for estimation of the microbial protein formation. In a second experiment, the same substrates were incubated for 96 hr in the HGT system (2 runs × 3 syringes) and gas production was measured after 2, 4, 6, 8, 12, 16, 24, 30, 36, 48, 60, 72 and 96 hr of incubation to obtain the fermentation kinetics and the time of half‐maximal gas production (t_1/2) of the substrates. The substrates differed considerably in their fermentation kinetics, and therefore, comparison on the basis of t_1/2 was chosen as the most meaningful. At t_1/2, microbial protein yield [g/kg dry matter] was higher for cellulose than for sucrose and pectin and higher for starch than for sucrose. The microbial protein expressed in g/L gas production was higher for starch and cellulose than for sucrose and pectin at t_1/2. Effects of carbohydrates related to ruminal pH may remain undetected in in vitro trials.     

耐受自身代谢产物及耐二甲基亚砜红霉素高产菌株的选育

为提高红霉素发酵单位,考察了二甲基亚砜(DMSO)添加时间和体积分数对红霉素合成的影响,采用筛选自身代谢产物突变株的方法,将突变株进行常压室温等离子体(ARTP)诱变和耐受高浓度DMSO处理。结果显示,在36 h向发酵瓶中添加30000μg/m L红霉素,筛选得到化学效价比对照提高22.4%的菌株。DMSO最适添加时间为发酵48 h,最适添加剂量为0.2%,其可提高发酵单位10.1%。     

Transmission of methicillin resistant Staphylococcus aureus among pigs during transportation from farm to abattoir

The prevalence of methicillin resistant Staphylococcus aureus (MRSA) in pigs at abattoirs is higher than in pigs sampled on farms. This study investigated whether MRSA negative pigs can become MRSA positive during transportation from the farm to the abattoir after exposure to other pigs and environmental sources of MRSA. Nasal swabs were collected from four batches of pigs during loading at the farm, on arrival at the abattoir and after stunning. Environmental wipes were taken from lorries after transporting pigs and from lairages after holding pigs. All pigs (n = 117) tested MRSA negative before transportation. On arrival at the abattoir, 12/117 (10.3%) pigs in two batches tested MRSA positive. In lorries that tested positive after transportation, the prevalence of MRSA positive pigs was 21.1%, whereas no MRSA was detected in pigs that had been transported in lorries that tested negative after transportation. At stunning, all batches and 70/117 (59.8%) pigs tested MRSA positive. Pigs can become MRSA positive in the short period of time during transportation from the farm to stunning at the abattoir.     

细菌耐药拮抗剂的研究

本文介绍了具有拮抗细菌耐药性作用的物质的研究进展情况，包括灭活酶抑制剂、药物渗透促进剂、外输泵抑制剂、细菌生物被膜抑制剂、抗菌药物增强剂、耐药质粒消除剂等。     

细叶百合低温解除休眠过程中鳞茎细胞淀粉粒及花芽分化的变化

以细叶百合为试材,通过低温(5℃)解除鳞茎休眠,研究了休眠解除过程中鳞茎细胞的淀粉粒的变化及细叶百合花芽分化的变化过程。通过石蜡切片和实体显微结构观察,结果表明,低温冷藏期间,顶芽生长锥的高度和宽度逐渐增加,细叶百合花芽分化主要分为4个时期,0~48 d为小花原基分化期,60 d为外轮花被原基分化期,72 d为内轮花被原基分化期,84 d为雄蕊和雌蕊原基分化期;鳞片及顶芽细胞内淀粉粒数量随着冷藏时间的延长逐渐减少。冷藏0~24 d内,鳞茎细胞没有进行有丝分裂,冷藏36 d以后细胞分裂数量逐渐增加,冷藏84 d分裂期细胞数量增加到2.6个。     

用绵羊小肠液冻干粉测定饲料过瘤胃淀粉小肠消化率方法的研究

本试验旨在以玉米为样本筛选用绵羊小肠液冻干粉测定精饲料瘤胃非降解残渣淀粉小肠消化率的最佳培养条件。分别研究了小肠液冻干粉用量(0.2、0.3、0.4、0.5和0.6g)对16h玉米瘤胃非降解残渣干物质和淀粉小肠消化率的影响;离体培养时间(4、8、12、16、20和24h)对16h玉米瘤胃非降解残渣干物质和淀粉小肠消化率的影响。结果表明,在本试验条件下,绵羊小肠液冻干粉测定玉米瘤胃非降解残渣淀粉小肠消化率的最佳用量为0.45g小肠液冻干粉/0.56g玉米瘤胃非降解残渣,最佳培养时间为12h。利用绵羊小肠液冻干粉测定常用饲料过瘤胃残渣淀粉小肠消化率的方法是可行的。     

细菌耐药质粒消除方法研究进展

常见的病原微生物多重耐药性的增加以及多重耐药菌株的出现,给动物养殖业造成了巨大的经济损失。细菌的耐药性与其自身携带的耐药质粒关系密切。论文从细菌耐药现状,细菌的耐药性和耐药质粒的关系,耐药质粒的物理、化学、中草药消除方法这几个方面进行综述,旨在寻求一种安全有效的消除方法消除耐药质粒,为今后相关的研究提供参考。     

Prevalence and antimicrobial resistance of MRSA across different pig age groups in an intensive pig production system in Australia

This observational study aimed to determine MRSA prevalence using strain‐specific real‐time PCR at the pig level, stratified by age groupings, within a pig enterprise. A total of 658 samples were collected from individual pigs (n = 618) and the piggery environment (n = 40), distributed amongst five different pig age groups. Presumptive MRSA isolates were confirmed by the presence of mecA, and MALDI‐TOF was performed for species verification. All isolates were tested against 18 different antimicrobials. MRSA was isolated from 75.2% (95% CI 71.8–78.6) of samples collected from pigs, and 71% of the MRSA isolates from this source were identified as community‐associated (CA)‐MRSA ST93, while the remainder were livestock‐associated (LA)‐MRSA ST398. Amongst environmental isolates, 80% (CI 64.3–95.7) were ST93 and the remainder ST398. All MRSA isolates from pigs and the environment were susceptible to ciprofloxacin, gentamicin, linezolid, mupirocin, rifampicin, sulfamethoxazole–trimethoprim, teicoplanin and vancomycin. Phenotypic rates of resistance were penicillin (100%), clindamycin (97.6%), erythromycin (96.3%), ceftiofur (93.7%), chloramphenicol (81.2%), tetracycline (63.1%) and amoxicillin–clavulanate (63.9%). A low prevalence of resistance (9.2%) was observed against neomycin and quinupristin–dalfopristin. The probability of MRSA carriage in dry sows (42.2%) was found to be significantly lower (p < .001) when compared to other age groups: farrowing sows (76.8%, RR1.82), weaners (97.8%, RR 2.32), growers (94.2%, RR 2.23) and finishers (98.3%, RR 2.33). Amongst different production age groups, a significant difference was also found in antimicrobial resistance for amoxicillin–clavulanate, neomycin, chloramphenicol and tetracycline. Using the RT‐PCR assay adopted in this study, filtering of highly prevalent ST93 and non‐ST93 isolates was performed at high throughput and low cost. In conclusion, this study found that weaner pigs presented a higher risk for CA‐MRSA and antimicrobial resistance compared to other age groups. These findings have major implications for how investigations of MRSA outbreaks should be approached under the One‐Health context.