培养料不同pH对真姬菇生长的影响

探讨不同初始pH值对真姬菇菌丝生长及产量的影响,来确定栽培料最适的初始pH值.结果表明:栽培料以灭菌前初始pH值7.5～8.0,日长速最快,达到6.45～7.14 mm,其产量最高,达到246.5～248.6 g/袋.     

Dynamics of phosphatase activities in a cork oak litter (Quercus suber L.) following sewage sludge application

As part of a study of the processes involved in litter biodegradation following sewage sludge (SS) addition, the variations over 14 months of phosphatase activities in a cork oak litter (Quercus suber L.) were investigated. A field experimental design was carried out using the litter-bag method on both a fertilized plot receiving SS applications (twice ) and a control plot. Acid (APH) and alkaline (BPH) phosphatases were measured, along with several biotic and abiotic variables potentially involved in the regulation of these enzymes. These included moisture, temperature, pH, water-extractable inorganic P (P_W), culturable heterotrophic bacteria and fungi. Sludge addition had significant effects on all the variables measured. Indeed, sludge increased significantly BPH activities, available P_W, microbial densities (i.e. bacteria and fungi) and pH in the fertilized plot. In contrast, APH activities decreased significantly following sludge addition. As a consequence, the BPH/APH ratio increased markedly and immediately in the fertilized plot, but only after the 1st amendment. Following the 1st preconditioning SS amendment, the 2nd fertilization had fewer effects on biological variables, because of summer dryness. The different properties examined varied significantly with incubation time, and most were significantly related to the seasonal patterns of litter moisture in this Mediterranean forest ecosystem. Hence, sewage sludge application modified the intensity of microbial responses to environmental factors, but biological patterns regulating P turn-over were maintained.     

一株可降解苹果废弃枝条的生防细菌鉴定

筛选对废弃苹果枝条具有降解作用的细菌,为农业废弃物的资源化利用奠定基础。首先利用稀释涂布法从采集的带菌苹果枝段中分离,再通过羧甲基刚果红培养基和复筛培养基挑选出产纤维素酶的菌株,利用发酵培养基验证筛选菌株的纤维素降解能力,进行腐烂病（Valsa mali）的对峙试验并测定其生防潜力,最后通过菌落形态、显微观察和gyrA序列的16S rDNA分析对细菌进行鉴定。从采集的苹果枝条中共分离出3株细菌,其中X-2菌株对苹果枝条具有降解作用,其最适生长pH为8,最适生长温度为30 ℃左右。菌株分泌产生的滤纸酶（FPAase）、β-葡萄糖苷酶和羧甲基纤维素酶（CMCase）活力分别高达（12.78±0.03） U/mL、（8.63±0.64） U/mL和（8.36±0.02） U/mL,枝条纤维素降解率高达12.36%±0.44%,经过16S rDNA序列测定和Blast 同源序列检索,得出该生防菌株X-2为解淀粉芽孢杆菌 (Bacillus amyloliquefaciens)。菌株X-2可以满足废弃苹果枝条的降解需求,其在碱性条件下生长良好,有望应用于碱性地区废弃枝条纤维素的降解。     

Molasses as C source for heterotrophic bacteria production on solid fish waste

The drumfilter effluent from a recirculation aquaculture system (RAS) can be used as substrate for heterotrophic bacteria production. These bacteria can be reused as aquatic feed. In RAS drumfilter effluents are organic carbon deficient for bacteria production. This is due to nitrogen accumulation in the system water. In the present experiment, a bacteria growth reactor (3.5l) was connected to the drumfilter (filter mesh size 60 μm) outlet of a recirculation system. To counteract carbon deficiency, different supplementation levels of molasses (organic carbon) were tested (carbon fluxes of 0.0, 3.2, 5.8, 7.8, 9.7 gC molasses/l/d; C:N ratios: 3.4, 6.4, 9.4, 13.0 and 16.5). The hydraulic retention time in the bacteria reactor was 6 h. For the maximum flux, the VSS and crude protein productions were about 168 gVSS and 95 g crude protein per kg feed. The maximum conversion of nitrate and ortho-phosphate was 24 g NO₃₋N and 4 gP/kg feed. This equals a conversion of 90% of the inorganic nitrogenous waste and 98% of the ortho-phosphate-P. Furthermore the maximum substrate removal rate and the K_s for molasses were determined (1.62 gC/l/h and 0.097 gC/l respectively). The maximum specific removal rate was 0.31 gC/gVSS/h and the related half saturation constant was 0.008 gC/l. The observed growth rate reached a maximum for C fluxes higher than 8 g/l/d. The present integration of heterotrophic bacteria production in RAS represents, therefore, an innovative option to reduce waste discharge by conversion. If the bacteria are reused as feed, system's ecological sustainability increases.     

Investigating the Link between Particulate Exposure and Airway Inflammation in the Horse

Inhalant exposure to airborne irritants commonly encountered in horse stables is implicated in the pathogenesis of inflammatory airway disease (IAD) and recurrent airway obstruction (RAO), non‐infectious, inflammatory pulmonary disorders that impact the health and performance of horses across all equine disciplines. IAD and RAO have overlapping clinical, cytological, and functional manifestations of the pulmonary response to organic dust and noxious gases encountered in the barn environment. Study of these diseases has provided important but incomplete understanding of the effect of air quality upon the respiratory health of horses. In this review, the principles of particulate exposure assessment, including health‐related aerosol size fractions and size‐selective sampling, the factors influencing air quality in equine environments, and the effect of air quality on the equine respiratory tract are discussed. The objective of this review is to provide the reader with a summary of the most common chronic inflammatory airway diseases in the horse and the principles of air sampling that are essential to the planning, interpretation, and assessment of equine respiratory health‐related exposure studies.     

内毒素血症对大鼠肠黏膜杯状细胞的影响

本研究选用39只140~150g SPF级SD大鼠作为动物内毒素血症模型,运用组织学常规HE染色和PAS染色技术,采取定性、定位和定量相结合的方法,通过观察不同试验组大鼠肠黏膜杯状细胞(GC)的数量和分布的动态变化来探讨内毒素(ET)对肠道黏膜免疫系统的影响。结果表明,ET能够破坏肠道黏膜的正常结构,影响肠黏膜的正常功能,同时能够在不同程度上降低GC数量,从而破坏肠道黏膜免疫系统。     

乳山湾东流区细菌数量的分布及与环境因子关系的研究

根据1995年6～9月对乳山湾东流区的微生物调查资料，研究了乳山湾东流区海水及底泥中细菌和弧菌量的变化及其与环境因子的关系。结果表明，该海域海水中细菌和弧菌的数量变化与温度的变化相一致，6月中旬～8月中旬，细菌数量增长比较缓慢，8月中旬开始，细菌数量增长较快，到8月底，达到最高值，异养菌为5．71×106cell／mL，弧菌为2．1×104cell／mL。而后，随着温度的下降，水中的细菌量逐渐减少。滩涂底泥中，细菌和弧菌的数量均比海水中细菌高l～2个数量级。     

Using cell and developmental biology to enhance embryo survival in aquaculture

Research on how the young embryo protects itself from normal environmental stresses reveals that the earliest phases of development have unique, innate mechanisms to protect the embryo during this most sensitive phase of embryogenesis. This paper shows ways in which knowledge of these protection mechanisms might be used to advantage in the aquaculture situation. These include novel mechanisms to deter bacteria and fungi such as secretion of anti-bacterial/anti-fungal substances from the egg at fertilization, as well as the utilization of anti-fungal metabolites provided by symbiotic bacteria associated with egg cases. UV damage is avoided by provision of unique sunscreens to the embryos so that UV penetration into the cytoplasm is avoided. Finally, embryos have exaggerated mechanisms to avoid the effect of toxicants on development but these are inadequate to remove pollutants present in feed used in aquaculture. Approaches are suggested on how this knowledge about adaptations might be used in the aquaculture setting to avoid pathogens, increase UV resistance and reduce levels of pollutants.     

Treatment of the early life stages of scallop (Pecten maximus) with antimicrobial agents; searching for an alternative to chloramphenicol

High mortality rates are often observed in rearing the early stages of the great scallop, Pecten maximus. The addition of antibacterial agents has been necessary to improve larval survival. However, as one antibacterial agent, chloramphenicol, is banned in Norway and Europe the aim of this study is to investigate alternative antibacterial agents. The therapeutic agents investigated in this study were florfenicol, oxytetracycline, oxolinic acid, neomycin and Pyceze. The mean minimum inhibitory concentration (MIC) values were determined for oxytetracycline, oxolinic acid and Pyceze against bacteria isolated from scallop larvae. Two types of treatment regime were investigated on an intermediate scale (20 L). One regime involved continuous exposure of scallop larvae to the therapeutic agent while the other involved a short exposure lasting two hours. All intermediate scale treatments were performed in parallel to large-scale production (800 L) treatment with chloramphenicol. Of the therapeutants investigated, oxolinic acid was the most effective, although only at high concentrations. The short exposure of two hours was ineffective for all therapeutics.