3种死菌悬液制备方法对PMA-qPCR结果的影响

本试验利用热灭活致死法、超声裂解致死法和紫外线照射法3种制备结核分支杆菌死菌悬液的方法,比较不同灭菌方法制备的死菌对PMA-qPCR偶联技术结果的影响,选择结核分支杆菌死菌悬液的最佳制备方法制备后续试验中用到的结核分支杆菌死菌;探索PMA-qPCR偶联技术的适用范围和局限性.结果表明,热灭活法和超声裂解致死法制备的结核分支杆菌死菌悬液影响PMA-qPCR检测的Ct值的变化;紫外线照射法制备的结核分支杆菌死菌悬液对PMA-qPCR检测的Ct值没有影响;热灭活法是制备结核分支杆菌死菌悬液的最佳方法;PMA-qPCR偶联技术不适用于细胞膜无损伤致死法制备死菌的检测.     

Surface decontamination of fresh-cut apple by pulsed light: Effects on structure,colour and sensory properties

The effect of pulsed light at increasing fluence (17.5, 52.5, 105.0 and 157.5 kJ/m²) was studied with reference to germicidal efficiency and changes in fresh-like appearance of sliced apple. Independent of fluence, viable counts and inoculated bacteria were reduced by 1 and 3 logs respectively. Fluence significantly affected weight loss, colour and sensory attributes of apple slices during storage at 6 °C. Pulsed light at 17.5 kJ/m² resulted in apple slices comparable to the untreated samples, with limited quality changes. By contrast, at higher fluence, apple slices underwent dehydration and browning due to loss of cell integrity. Exposure to high fluence treatments was also associated with negative changes in the flavour profile of sliced apple during storage.     

Pre-exposure to infectious hypodermal and haematopoietic necrosis virus or to inactivated white spot syndrome virus (WSSV) confers protection against WSSV in Penaeus vannamei (Boone) post-larvae

Larvae and post-larvae of Penaeus vannamei (Boone) were submitted to primary challenge with infectious hypodermal and haematopoietic necrosis virus (IHHNV) or formalin-inactivated white spot syndrome virus (WSSV). Survival rate and viral load were evaluated after secondary per os challenge with WSSV at post-larval stage 45 (PL45). Only shrimp treated with inactivated WSSV at PL35 or with IHHNV infection at nauplius 5, zoea 1 and PL22 were alive (4.7% and 4%, respectively) at 10 days post-infection (p.i.). Moreover, at 9 days p.i. there was 100% mortality in all remaining treatments, while there was 94% mortality in shrimp treated with inactivated WSSV at PL35 and 95% mortality in shrimp previously treated with IHHNV at N5, Z1 and PL22. Based on viral genome copy quantification by real-time PCR, surviving shrimp previously challenged with IHHNV at PL22 contained the lowest load of WSSV (0-1x10(3) copies microg-1 of DNA). In addition, surviving shrimp previously exposed to inactivated WSSV at PL35 also contained few WSSV (0-2x10(3) copies microg-1 of DNA). Consequently, pre-exposure to either IHHNV or inactivated WSSV resulted in slower WSSV replication and delayed mortality. This evidence suggests a protective role of IHHNV as an interfering virus, while protection obtained by inactivated WSSV might result from non-specific antiviral immune response.     

超声技术在食品杀菌及废水处理中应用的研究进展

介绍了超声的定义和超声杀菌的机理。综述了近些年来超声在食品杀菌及废水处理领域的研究进展,重点阐述超声与其他技术结合使用的杀菌效果,并提出了超声在这些领域中的研究发展方向。     

Studies on the inactivation of selected viral and bacterial fish pathogens at high pH for waste disposal purposes

This study investigated the use of alkaline hydrolysis at ambient temperature for inactivation of selected fish pathogens in fish tissues under conditions approximating those that are likely to be found in the aquaculture industry. Infectious salmon anaemia virus (ISAV) and Lactococcus garvieae have been determined in a previous study to be the most resistant virus and bacteria to pH 12 from a wide range of viruses and bacteria tested. They were spiked at high titres into fish extracts that were then treated with 1 m sodium hydroxide (NaOH). Viable L. garvieae was not detected in the treated fish extract after 1 h, and ISAV was not detected after 24‐h exposure. Field mortalities of Atlantic salmon, Salmo salar L., caused by infectious pancreatic necrosis virus were treated by alkaline hydrolysis at ambient temperature. The macerated fish mortalities contained a high titre of virus (3.38 × 10⁸ TCID₅₀ g^?1) that was reduced to approximately 2.2 × 10³ TCID₅₀ g^?1 after 24‐h exposure to NaOH, and virus was not detected after exposure for 48 h. The results suggest that alkaline hydrolysis at ambient temperature has potential as a biosecure treatment method for fish by‐products containing fish pathogens.     

双亲灭活原生质体融合技术在草菇耐低温菌株选育上的应用

为了选育耐低温草菇菌株,以草菇V23、V3552为亲本,采用酶解法制备原生质体,用紫外诱变、化学诱变两种方法对草菇菌株进行诱变,筛选到耐低温的突变株;然后利用紫外灭活（20 W,30 cm,110 s）和热灭活（50℃ 3 min）的双亲灭活标记法对突变株进行化学融合,结果表明在400 g/L的PEG6000、pH 8.0、融合时间30 min和融合温度32℃的条件下融合率最高,达到0.517%, 共获得200个融合子。经过0℃低温筛选,最终获得15株草菇耐低温菌株,菌丝在0℃的耐冻能力提高了4.5倍。经出菇实验证明其子实体与出发菌株相比具有明显的耐低温性,液化现象明显推迟,说明该方法筛选出的菌株具有进一步应用开发的价值。     

Incidence, appearance and development of potato mop-top furovirus-induced spraing in potato cultivars and the influence on yield, distribution in Denmark and detection of the virus in tubers by ELISA

Summary 23 potato cultivars were grown in fields infested with potato mop-top virus and spraing was assessed on tubers at harvest and after storage. Large differences in spraing susceptibility were found between cultivars. Compared with other countries, spraing in Denmark is characterised by a high incidence at harvest, a low increase during storage and a very low proportion of superficial spraing. Decrease in spraing during storage was recorded in two cultivars. DASELISA tests for PMTV in tubers revealted a high reliability. Mapping of PMTV in important Danish potato growing areas showed that the virus is widespread. Occurrence of spraing did not influence total yield or dry matter content. Soil acidity did not influence incidence of spraing but it was more common on coarse-grained soil than on finer sandy soils. PMTV in viruliferous resting spores ofSpongospora subterranea was inactivated by heating to 90°C for 15 minutes.     

银翘散体外抗禽流感病毒的研究

文章探讨银翘散在鸡胚、MDCK细胞上对H9亚型、H5亚型禽流感病毒的直接灭活、治疗和预防作用。结果表明,在鸡胚中银翘散对H9亚型、H5亚型禽流感病毒直接灭活、治疗和预防浓度分别是31.25、15.625、62.5 mg.mL-1。在MDCK细胞上银翘散对H9亚型禽流感病毒直接灭活、治疗和预防浓度分别是7.812、125、125 mg·mL-1,对H5亚型禽流感病毒直接灭活、治疗和预防浓度分别是15.62、125、250 mg·mL-1。     

Host range and properties of <Emphasis Type="Italic">Tomato chlorotic dwarf viroid</Emphasis>

We characterised the host range and physical properties of Tomato chlorotic dwarf viroid. Among the 46 plant species inoculated with the viroid, two in the family Compositae and 23 in the family Solanaceae were found to be systemic hosts. The viroids in the crude sap from diseased tomato plants were thermally inactivated by heating to 100°C for at least 40 min. These viroids also lost their infectivity when diluted in phosphate buffer to at least 10⁻⁶, or after 3 days of incubation at room temperature. However, the infectivity of the viroids in dried crude sap from the plants persisted throughout the 50-day test period.