绿僵菌液体培养的条件及其对马尾松毛虫的毒力

在不同温度和不同光照条件下对3株金龟子绿僵菌和1株贵州绿僵菌的液体深层培养研究表明，光照对菌丝生长和液生分生孢子产量均无显著影响。但培养温度显著影响菌丝生长和液生分生孢子的产出率，25-28℃为液体深层培养绿僵菌的适宜温度，其中以28℃最佳，对3-4龄马尾松毛虫幼虫的室内毒力测定表明，绿僵菌液生分生孢子的毒力略低于气生分生孢子。     

多位点酶电泳在黄芪根瘤菌分类中的应用

报导了分析根瘤菌各种多位点酶的电泳缓冲系统和染色方法，并对黄芪根瘤菌进行了分类研究，结果表明：采用多位点酶电泳图谱进行聚类可得到与数值分类基本一致的结果，证实这是一种行之有效、简便快速的分类方法．     

Impact of a native Streptomyces flavovirens from mushroom compost on green mold control and yield of Agaricus bisporus

ABSTRACT

Thirty-five actinobacterial isolates, obtained from button mushroom (Agaricus bisporus) substrates (i.e., compost in different phases of composting, black peat or casing layer) in Serbia in 2014–2016 were tested in vitro against the causal agents of green mold in cultivated mushroom. Out of six most promising isolates, A06 induced 42.4% in vitro growth inhibition of Trichoderma harzianum T54, and 27.6% inhibition of T. aggressivum f. europaeum T77. The novel strain A06 was identified as Streptomyces flavovirens based on macroscopic and cultural characteristics and 16S rDNA sequence and used in mushroom growing room experiments. Actinobacteria had no negative influence on mycelial growth of the cultivated mushroom in compost in situ. Isolate S. flavovirens A06 enhanced mushroom yield significantly, up to 31.5%. The A06 isolate was more efficient in enhancing yield after inoculation with the compost mold T. aggressivum (26.1%), compared to casing mold T. harzianum (8%). Considering disease incidence, actinobacteria significantly prevented green mold in compost caused by T. aggressivum (6.8%). However, fungicide prochloraz-Mn had a more significant role in reducing symptoms of casing mold, T. harzianum, in comparison with actinobacteria (24.2 and 11.8%, respectively). No significant differences between efficacies of S. flavovirens A06 and the fungicide prochloraz-Mn against T. aggressivum were revealed. These results imply that S. flavovirens A06 can be used to increase mushroom yield and contribute to disease control against the aggressive compost green mold disease caused by Trichoderma aggressivum.     

The StepOne real-time polymerase chain reaction detection of Salmonella sp., Salmonella enterica ser. typhimurium and enteritidis in milk and meat

The aim of this study was to follow contamination of ready to eat milk and meat products with Salmonella spp. by using the StepOne real-time polymerase chain reaction (PCR). Classical microbiological methods for detection of foodborne bacteria involve the use of pre-enrichment and/or specific enrichment, following isolation of bacteria in solid media and the final confirmation by biochemical and/or serological tests. We used the PrepSEQ Rapid Spin Sample Preparation Kit for isolation of DNA and MicroSEQ® Salmonella spp. Detection Kit for pursuance of the real-time PCR (Applied Biosystems). In samples without incubation we detected strain of Salmonella sp. in 5 out of 25 samples (swabs), as well as in the internal positive control (IPC), which was positive in all samples. This StepOne real-time PCR assay is extremely useful for any laboratory equipped by real-time PCR. It is a fast, reproducible, simple, specific and sensitive way to detect nucleic acids, which could be used in clinical diagnostic tests in the future. Our results indicated that real-time PCR assay developed in this study could sensitively detect Salmonella spp. in ready-to-eat food. This could prevent infection caused by Salmonella, and also could benefit food manufacturing companies by extending their product's shelf-life as well as saving the cost of warehousing their food products while awaiting pathogen testing results.     

高温厌氧消化中底物浓度对病原指示微生物杀灭的影响

剩余污泥中含有大量病原微生物,土地利用之前必须进行适当的处理,降低病原微生物的数量,以降低环境风险.通过研究在不同的底物浓度条件下,剩余污泥高温厌氧消化(55℃)过程对病原指示微生物的杀灭效果,分析厌氧消化前后污泥中病原指示微生物数量变化的原因.结果表明,随着底物浓度的增加,VFAs浓度和累积产甲烷量增加.在底物浓度为28~84 g·L-1、温度为55℃、持续28 d的高温厌氧消化过程中,上清液中总大肠杆菌下降2.0~3.0个数量级、粪大肠杆菌下降1.8~3.3个数量级;消化后污泥中总大肠杆菌和粪大肠杆菌杀灭率均达到99%以上;且上清液中和消化污泥中均未检测到沙门氏菌的存在.在研究底物浓度范围内,当底物浓度大于45 g·L-1时,消化液和污泥中总大肠杆菌和粪大肠杆菌的杀灭效果下降.     

Chemical synthesis of 6-pentyl-2H-pyran-2-one: a natural antifungal biosynthesized by Trichoderma spp.

Trichoderma spp. biosynthesize 6-pentyl-2H-pyran-2-one (6-PP), a natural antifungal pyrone which could be used as biological control agent (BCA). Unfortunately, biotechnical processes are limited by inhibition of biomass at high concentration of 6-PP. We report herein a new easy synthesis of this natural pyrone, using readily available starting materials. This synthesis, compatible with a large production scale, permit to obtain overweight amounts of 6-PP that in biotechnological routes.     

河套地区几种沉水植物无性繁衍特性研究

沉水植物对于湖泊生态系统有着重要的作用,它们不仅是水生环境食物链中重要的生产者,同时还对湖泊的营养物沉积和循环有着重要的作用,从而影响着湖泊的富营养化进程。本文以黄河内蒙古段河套灌区湖泊中常见的三种沉水植物篦齿眼子菜（Potamogeton pectinatus）、穿叶眼子菜（Potamogeton perfoliatus Linn）和狐尾藻（Myriophyllum verticillatum）为研究对象,对其无性繁殖方式和能力进行了初步研究。观察了这三种植物的营养繁殖结构,并利用茎节切段进行了人工培养试验。结果表明：三种植物均具有很高的营养繁殖潜力。由茎节处萌发新芽和新根并逐渐形成完整的植物体。植株地上部分截断后扦插及漂浮水中处理的成活率较高。而截断后的地下根茎及匍匐茎埋入淤泥后成活率极低。根据三种植物的营养繁殖潜力,探讨了人为收获这些植物的可能性以及其利用潜力。同时,评估了收获这些植物可能对湖泊水生植物群系改变以及湖泊富营养化转型的风险。     

Water quality supply in a Portuguese teaching hospital: monitoring and studies on detection of critical points

Surveillance of drinking water quality is extremely important to human health, assuming greater relevance in hospital environments, especially to those individuals who are immunocompromised. This study is aimed to determine the effect of increasing free chlorine (Cl) concentration in a hospital water network in regard to water quality monitoring and microbial growth control, between 2010 and 2013 in Porto. The average of free Cl concentration in the period under analysis showed some heterogeneity per floor, varying between 0.84 and 1.25 mg/L. In addition, there was a rise in proportion of samples that exceeded WHO guidelines (free Cl ≥ 0.5 mg/L), particularly in the last two years of the same period. With respect to microbial analysis, 22.4% of the samples were positive for Legionella spp., 6.4% for Pseudomonas aeruginosa, 15% and 30.4% for aerobic plate counts at 36 and 22 ºC, respectively. The proportion of positive samples decreased throughout the period under analysis, in particular for Legionella spp. (41.7% in 2010 vs. non-detectable in 2013) and P. aeruginosa (10.8% in 2010 vs. 3.3% in 2013). These results are in accordance with the gradual rise in free Cl concentration (0.78 ± 0.94 mg/L in 2010 vs. 1.16 ± 0.51 mg/L in 2013). In conclusion, a suitable plan for drinking water quality was instituted which resulted in reducing microbiological growth in the waterwork network, improving public health protection. However, the detection of critical points associated with lower levels of free Cl were found on certain floors/points-of-use, requiring the need to improve the monitoring water treatment system and/or implementation of additional technologies.     

A Critical Review of Assumptions About the Prairie Dog as a Keystone Species

Cynomys spp.) have been labeled as keystone species because of their influence on biological diversity and ecosystem function. However, the validity of several assumptions used to support keystone status is questionable. We review the strength of the evidence and the magnitude of the prairie dog's effects on ecosystem structure and function. We use this review to reevaluate the keystone role for prairie dogs. Our goal is to encourage sound management of the prairie dog ecosystem by improving the ecological foundation of their keystone status. Our review confirms that prairie dogs affect a number of ecosystem-level functions but that their influence on prairie vertebrates may be less than previously suggested. Species richness and abundance patterns were variable among plants, mammals, and birds and were not consistently higher on prairie dog colonies compared to uncolonized areas. In addition, only nine of the 208 species listed in the literature as observed on or near prairie dogs colonies had quantitative evidence of dependence on prairie dogs. Abundance data indicated opportunistic use of colonies for an additional 20 species. A total of 117 species may have some relationship with prairie dogs, but we lacked sufficient data to evaluate the strength of this relationship. The remaining 62 species may be accidental or alien to the system. Despite our conclusion that some prairie dog functions may be smaller than previously assumed, collectively these functions are quite large compared to other herbivores in the system. We suggest that prairie dogs also provide some unique functions not duplicated by any other species and that continued decline of prairie dogs may lead to a substantial erosion of biological diversity and landscape heterogeneity across prairie and shrub-steppe landscapes. Thus, we concur that keystone status for prairie dogs is appropriate and may aid conservation efforts that help protect species dependent on prairie dogs and support other important ecosystem functions.     

沉水植物黑藻腐解对微囊藻休眠体复苏的影响

模拟沉水植物黑藻(Hydrilla verticillata)生物量(以湿质量计)分别为0、10、25和50 g时,在17℃下腐解过程中对微囊藻(Microcystis)休眠体复苏的影响,并通过测定沉积物和上覆水的理化指标,探究腐解过程中环境因素的变化及其对微囊藻复苏的影响.为期84 d的腐解试验结果显示,沉水植物黑藻的腐解对微囊藻休眠体复苏具有抑制作用,且黑藻生物量越高抑制作用越强.另外,水体及沉积物中的TN、TP和总有机物含量,沉积物表面的光照强度及pH均随黑藻的腐解时间及黑藻生物量的不同而变化.黑藻的腐解会使沉积物中w(TN)升高;与无黑藻组相比,黑藻生物量越多释放到上覆水中的TN越多,但由于沉积物的吸附及微生物的作用,各试验组中上覆水ρ(TN)呈逐渐下降趋势;黑藻的腐解引起沉积物w(TP)显著升高,并在短时间内造成上覆水中ρ(TP)增加,64 d后复原到初始水平;沉积物及水体中的总有机物含量呈先升后降的趋势,在腐解后期水体中ρ(TOC)基本恢复到初始水平.在腐解过程中抑制微囊藻复苏生长的因素可能包括ρ(TP)的升高及光照强度和pH降低.