三种赤潮微藻基因组DNA快速制备方法的研究

采用超声波法、煮沸法和微波法3种方法分别对塔玛亚历山大藻、环状异帽藻和角毛藻进行细胞破碎及快速制备基因组DNA的研究。通过细胞计数和DNA浓度测定的手段对三种方法进行了比较,以选择适合不同藻种的细胞破碎方法。结果表明,塔玛亚历山大藻和环状异帽藻用超声波法破碎效果较好;角毛藻用微波法较好。对用该三种方法制备的基因组DNA做了PCR扩增,电泳检测表明,与CTAB法扩增效果一样。本文建立的微藻DNA快速制备方法有望应用在赤潮藻类的快速分子鉴定方面。     

A comparison of two methods for the isolation of free and occluded particulate organic matter

Various methods exist for the isolation of particulate organic matter (POM), one of the soil‐organic‐matter (SOM) fractions reacting most sensitive on land‐use or soil‐management changes. A combination of density separation and ultrasonic treatment allows to isolate two types of POM: (1) free POM and (2) POM occluded in soil aggregates. POM fractions are closely linked to their biochemical function for the formation and stabilization of aggregates, therefore methods using different aggregate sizes may result in different POM fractions isolated. We evaluated two physical fractionation procedures to reveal whether they yield different POM fractions with respect to amount and composition, using grassland and arable soils with sandy‐loam to sandy–clay‐loam texture and thus low macroaggregate stability. Method I used air‐dried aggregates of <2.0 mm size and a low‐energy sonication for aggregate disruption, method II used field‐moist aggregates <6.3 mm and a high‐energy–sonication procedure for aggregate disruption. POM fractions were analyzed by elemental analysis (C, N) and CPMAS ¹³C‐NMR spectroscopy. With both methods, about similar proportions of the SOM are isolated as free or occluded POM, respectively. The free‐ and occluded‐POM fractions obtained with method I are also rather similar in C and N concentration and composition as shown by ¹³C‐NMR spectroscopy. Method II isolates a free‐ and occluded‐POM fraction with significantly different C and N concentrations. NMR spectra revealed significant differences in the chemical composition of both fractions from method II, with the occluded POM having lower amounts of O‐alkyl C and higher amounts of aryl C and alkyl C than the free POM. Due to the use of larger, field‐moist aggregates with minimized sample pretreatment, two distinctly different POM fractions are isolated with method II, likely to be more closely linked to their biochemical function for the formation and stabilization of aggregates. High‐energy sonication as in method II also disrupts small microaggregates <63 µm and releases fine intraaggregate POM. This fraction seems to be a significant component of occluded POM, that allows a differentiation between free and occluded POM in sandy soils with significant microaggregation. It can be concluded, that microaggregation in arable soils with sandy texture is responsible for the storage of a more degraded occluded POM, that conversely supports the stabilization of fine microaggregates.     

The solubilization of myofibrillar proteins of vertebrate skeletal muscle in water

Myofibrillar proteins of vertebrate skeletal muscles are insoluble in solutions of ionic strength that approximate physiological conditions. We established a method to solubilize more than 80% of chicken breast muscle myofibrillar proteins in water for the use of meat as a source of food protein. SDS‐polyacrylamide gel electrophoretic patterns of water‐soluble myofibrillar proteins demonstrated that all identified myofibrillar proteins except connectin/titin were soluble in water. A part of α‐actinin was released from myofibrils by repeated washing with 2.5 mmol/L NaCl and 5 mmol/L L‐histidine solution, and subsequent destruction of connectin/titin in washed myofibrils by ultrasonication resulted in solubilization of a large fraction of chicken breast muscle myofibrillar proteins in water. Myofibrillar proteins of chicken leg, pork loin, beef shoulder loin, and lamb were also solubilized in water using this procedure.     

超声离心工艺制备氧化石墨烯纳米片

以天然石墨粉为原料,采用改进的Hummers法制备氧化石墨烯,将得到的氧化石墨烯水分散液在超声中进行超声破碎,可以得到不同尺寸的氧化石墨烯片,再采用离心工艺进行离心分离,最后得到尺寸分布较窄的氧化石墨烯纳米片。对大量的氧化石墨烯扫描电子显微镜照片进行统计分析发现,通过调整超声功率、超声时间、离心转速和离心时间可以有效地调控得到的氧化石墨烯纳米片的片径尺寸。最后,采用优化后的工艺参数,超声离心工艺制备出了平均片径尺寸约为100 nm的氧化石墨烯纳米片,其中尺寸小于100 nm氧化石墨烯纳米片的含量超过了60%。     

超声-冻融联合技术对污泥理化性质的影响

为提高污泥的破解效率,采用超声-冻融联合技术破解南昌市某污水处理厂二沉层污泥,选择声能密度、超声时间、冷冻时间、冷冻温度等4个因素为试验参数,设计3因素4水平和1因素2水平（34×12）的混合正交试验,分析在不同处理条件下污泥的理化性质。结果表明：超声和冻融不仅可促进污泥中可溶性化学需氧量、总氮和总磷的释放,还能有效降低污泥重金属含量,且超声的作用效果优于冻融。在最佳试验条件下污泥向上清液释放的 SCOD、TN 和 TP 分别是原来的5．70、5．34和1．94倍,污泥重金属权重离子冲量ωI 降至原来的88％。     

微生物酶法测定菜籽粕中硫甙含量

菜籽粕是一种优良的蛋白质饲料资源,其脱毒利用受到广泛的关注.作为菜籽粕脱毒微生物之一,黑曲霉能有效降低菜籽粕中的植酸和硫甙含量.本研究旨在通过超声破碎技术从筛选到的1株具硫甙降解能力的黑曲霉(Aspergillas niger)H23中提取胞内芥子酶,建立微生物酶测定菜籽粕中硫甙含量的方法.此法首次在硫甙测定中使用微生...     

Assessment of the genetic diversity of Xylella fastidiosa in imported ornamental Coffea arabica plants

A study was performed in order to assess the presence of Xylella fastidiosa in imported ornamental plants, among them Olea europaea, Coffea arabica and Nerium oleander. Positive results were only obtained from C. arabica, where 15 plant samples tested positive for X. fastidiosa by PCR, nine from Costa Rica and six from Honduras. Transmission electron microscopy observations indicated that rod‐shaped bacterial cells exhibiting the characteristics of X. fastidiosa cells were present in the xylem vessels of leaf petioles obtained from the infected C. arabica plants. Diversity of X. fastidiosa in C. arabica plants was assessed through a multilocus sequence typing (MLST) analysis of seven housekeeping genes (leuA, petC, lacF, cysG, holC, nuoL and gltT) and compared with X. fastidiosa infecting different host plants worldwide. Based on this MLST analysis, the prevalence of different sequence types (STs) of X. fastidiosa in the C. arabica ornamental plants was demonstrated and related to different X. fastidiosa subspecies, underlining the risk of introducing additional genetic diversity for X. fastidiosa to Europe. ST53, related to X. fastidiosa subsp. pauca, was frequently found in these C. arabica samples. A second ST related to X. fastidiosa subsp. pauca, ST73, has been assessed in coinfection with ST53 in one individual plant. Additionally, ST72 and ST76, related to X. fastidiosa subsp. fastidiosa, have been recorded. Next to these previously described STs, a novel ST, namely ST77 has been revealed, related to X. fastidiosa subsp. fastidiosa. Isolation of X. fastidiosa from leaf petioles and midribs of infected C. arabica plants was successfully performed only after the application of an additional ultrasonication step during the extraction procedure. Based on this approach, a number of X. fastidiosa isolates were obtained and further characterized.     

超声波预处理对水酶法提取扁桃仁油及水解蛋白影响的研究

以扁桃仁为原料,在水酶法提取扁桃仁油及水解蛋白前对原料进行超声波预处理。通过单因素试验与正交试验,确定最佳处理条件为:超声波功率300 W,温度40℃,时间15 min。在此条件下,扁桃仁油与水解蛋白提取率分别为80.43%和89.59%,比未经超声波预处理分别提高4.4%和5.2%。通过番红染色法观察了超声波与纤维素酶对原料细胞的破坏效果。     

无乳链球菌乳酸-羟基乙酸共聚物微球的制备及其体外释放特点分析

以乳酸-羟基乙酸共聚物（PLGA）为材料,采用复乳溶剂挥发法制备无乳链球菌（Streptococcus agalactiae）全菌及超声破碎后的上清微球疫苗。显微镜观察显示随着 PLGA 质量浓度、PVA（聚乙烯醇）质量浓度和外水相体积的增加,上清微球平均粒径均随之增大。最终确定上清微球制备条件为 PLGA 质量浓度25 mg·mL -1、PVA 质量浓度1 mg·mL -1、外水相体积20 mL。全菌微球制备条件与上述的相比,仅 PVA 质量浓度调整为2 mg·mL -1。扫描电镜观察显示全菌和上清微球平均粒径分别为9.4μm 和3.9μm,微球均呈球形。BCA（二喹啉甲酸）法分析显示包封率分别为68.07％和63.49％;载药量分别为5.49＆#215;108个·mg -1和3.58％;28 d 体外累积释放量分别为64.2％和82.8％。     

超声波协同有机酸去除城市污泥中的重金属

利用超声波协同乙酸和柠檬酸处理城市污泥,就超声波条件对有机酸去除污泥重金属的影响进行了研究．结果表明,随着超声波处理时间的延长,两种酸对污泥重金属的去除率相应增加．在以0．1mol／L乙酸和0．1mol／L柠檬酸酸化后,经超声波处理20min,对污泥中cu的去除率较单独酸化处理分别增加了4．0％和4．6％、对Zn的去除率分别增加了13．3％和12．2％、对Pb的去除率分别增加了3．6％和15．9％,表明超声波作用强化了两种酸对重金属的提取,具有明显的协同效应．在重金属提取过程中,有机酸的作用是主要的,而超声波是协同手段,其协同贡献率因重金属不同而不同,其中以对Pb去除的协同贡献最高,为15．9％．对重金属去除条件优化分析表明,超声波处理20min明显有利于重金属的溶出,相同浓度条件下柠檬酸对重金属的提取能力强于乙酸．