细菌荚膜多糖的分离纯化研究进展

荚膜多糖是细菌的保护性抗原和毒力因子,也是细菌疫苗最重要的靶抗原之一,其分离纯化是制作疫苗的首要步骤。本文从去除菌体、收集总糖、去除菌体核酸和蛋白质、去除内毒素等基本工艺步骤,对现有的工艺和目前的工艺进展进行了综述,重点阐述了中空纤维、深层过滤、超滤、酶水解、柱层析等方法在荚膜多糖分离纯化中的应用进展。     

SSU1多拷贝表达对酿酒酵母二氧化硫生成量的影响

【目的】在不影响酵母正常代谢前提下,构建亚硫酸盐分泌量提高的基因工程菌株,增加二氧化硫生成量,有效地解决啤酒老化问题。【方法】以适量高产二氧化硫工业啤酒酵母突变株M8总DNA为模板,PCR方法得到带有不同长度5′端非编码区的基因片段SSU1-1、SSU1-2,以大肠杆菌-酿酒酵母穿梭质粒YEp352构建表达载体pSU1和pSU2,转化实验室酵母YS58,验证SSU1多克隆表达对其二氧化硫生成量的影响。进而将pSU2转化工业啤酒酵母M8,利用亚硫酸盐抗性筛选转化子,并对其二氧化硫和硫化氢生成量及其啤酒抗老化性能进行测定和分析。【结果】实验室酵母转化子pSU1-4和pSU2-3二氧化硫生成量较原株明显提高而硫化氢生成量基本不变,工业啤酒酵母转化子Y2二氧化硫生成量比原株M8提高74.4%,TBA值下降14.9%,DPPH自由基清除率提高38.2%,硫化氢生成量基本不变。【结论】SSU1基因的多拷贝表达有效提高了亚硫酸盐转运蛋白Ssu1p表达量,增加了亚硫酸盐分泌量,啤酒抗氧化能力得到明显增强,而对酵母硫代谢途径中亚硫酸盐还原为硫化物代谢过程没有影响。     

污泥颗粒化技术在废水处理中的应用

以厌氧颗粒污泥为代表的污泥颗粒化技术具有容积负荷高、节省沉淀分离空间、节能减排、单位投资成本和运行成本低等优点,在废水处理中得到广泛应用。近年来,好氧和缺氧颗粒污泥技术也受到关注,在去除废水中有机物的同时还可实现对氮磷的同步去除,其中好氧颗粒污泥技术已在国外实现了工业应用。文章从厌氧、好氧和缺氧颗粒污泥的起源和发展、运行条件对颗粒形成的影响、废水处理反应器和工程应用等几个方面进行综述和总结,分析了目前颗粒技术在应用中存在的问题,并对污泥颗粒化技术的发展前景进行了展望。     

地木耳挂袋法监测大气SO_2污染的可行性研究

本文用地木耳和碱片同步监测了白银地区某冶炼厂及其四周大气中的二氧化硫浓度。经地木耳含硫量与大气二氧化硫污染浓度的相关分析表明：地木耳含硫量与大气二氧化硫污染浓度之间有密切相关性。利用地木耳挂袋法监测大气ＳＯ＿２污染具有可比性强、容污量大、布点灵活,经济方便等优点,适宜于大范围内甚至世界范围内统一监测大气ＳＯ＿２污染应用。     

污水渗滤湿地处理系统技术的研究进展

由于渗滤湿地污水处理系统具有很高的净化效率和相对较低的基建投资和处理成本,目前正渐渐在许多国家得到较为广泛的应用．本文简要论述了渗滤湿地的构造与渗滤介质、N和P的去除过程与净化机理、技术性能、现行的设计方法、运行与调控机制、土壤堵塞问题与解决途径、垂直流与水平流人工湿地处理系统的组合及其在不同类型废水处理中的应用等．最后,探讨了这一技术的研究发展方向．     

粘土改性技术用于絮凝除藻的研究进展

当前, 藻类水花及其带来的藻毒素污染愈演愈烈, 治理藻害成为改善水环境的当务之急。受安全、技术及成本的限制, 人们试图通过改性粘土实现更加高效、安全的藻害去除效果。基于已有的研究成果, 对改性粘土的除藻机理、改性方法及絮凝效果的影响因素进行了归纳总结。目前, 改性粘土去除藻害的研究和应用大多局限于海水水体, 很多淡水除藻的研究和实践尚未取得理想效果。今后可以考虑通过有机-无机改性结合的方法或开发新型改性剂拓展改性粘土技术絮凝除藻的应用范围。总之, 开发相对安全、可防止蓝藻泛起、藻毒素释放及底泥营养盐二次污染等问题的改性粘土来絮凝沉降藻类, 是未来利用改性粘土治理藻害需要解决的问题和重点研究方向。     

一种高质量麦冬总RNA的提取方法

本方法采用CTAB作为去污剂,分别用氯仿/异戊醇反复抽提、LiCl沉淀,以去除蛋白质、碳水化合物和次生代谢物等杂质,用DNase处理去除DNA污染,最后用无水乙醇沉淀获得总RNA。该方法不仅能获得完整性好、纯度高的总RNA,而且操作简单、成本低廉、RNA产率高,对富含次生物质的中草药材植物组织总RNA的提取具有借鉴意义。     

自然干燥紫萼藓总RNA提取方法

介绍一种适合富含酚类、萜类等次生物质的干燥紫萼藓的总RNA的提取方法—SDS/酸酚法。采用SDS做为去污剂,用水饱和酚、氯仿和异戊醇进行抽提以去除蛋白、酚类等次生物质,醋酸钾和无水乙醇去除多糖等物质,最后LiCl沉淀获得总RNA。该方法不但获得了完整性好和纯度高的RNA,而且操作简单,成本也较低,对其他富含酚类、萜类等次生物质的干燥植物组织的总RNA的提取具有借鉴意义。     

生物淋滤技术在去除污泥中重金属的应用

利用微生物方法去除污泥中重金属（生物淋滤法）具有成本低,去除效率高,脱毒后污泥脱水性能好等优点,近年来在国际上备受关注,生物淋滤法采用的主要细菌为氧化亚铁硫杆菌（Thiobacillus ferrooxidans)和氧化硫硫杆菌（Thiobacillus thiooxidans),在其作用下,污泥中以难溶性金属硫化物被氧化成金属硫酸盐而溶出,通过固液分离即可达到去除重金属的目的,污泥的生物淋滤效果受温度、O2和CO2浓度,起始pH、污泥种类与浓度、底物种类与浓度、抑制因子、Fe^3 浓度等的影响,较为详细地介绍了生物淋滤法的作用机理及高效去除污泥中重金属的操作程序,并对其在环境污染治理方面的应用前景作了分析。     

单克隆抗体纯化过程中内毒素去除方法分析

目的：分析单克隆抗体纯化过程中,去除内毒素的不同方法的应用效果,并探讨它们应用于中试规模的可行性。方法与结果：比较了多聚赖氨酸型的内毒素去除填料、20nm膜过滤、将单抗附着在蛋白A柱上后使用精氨酸和组氨酸溶液冲洗等3种方法的内毒素去除效果,发现3种方法都可以将内毒素水平大幅降低,可分别将内毒素去除70％、88％和97％。因为单抗分子等电点较高,所获得的最低内毒素含量为0．2～0-3EU／mg。结论：3种方法均具有一定的工艺放大潜力,进一步提高内毒素去除效果将需要综合使用不同机理的去除技术。     

熏蒸法测定土壤微生物量碳的改进

自从Ｊｅｎｋｉｎｓｏｎ和Ｐｏｗｌｓｏｎ［１］创造熏蒸培养方法测定土壤微生物量碳，发展到用多种方法来测定土壤微生物量，如土壤ＡＴＰ含量分析方法［２］，基质诱导呼吸法［３］，精氨酸氨化法［４］，熏蒸浸提法［５］，脂肪酸、ＤＮＡ、ＲＮＡ等微生物细胞成分分析...     

Evaluating soil microbial carbon use efficiency explicitly as a function of cellular processes: implications for measurements and models

Carbon use efficiency (CUE), the proportion of carbon (C) consumed by microbes that is converted into biomass, is an important parameter for soil C models with explicit microbial controls. While often considered as a single parameter, CUE is an emergent property of multiple microbial processes, including assimilation efficiency, biomass-specific respiration, enzyme production, and respiratory costs of enzyme production. These processes occur over variable time scales and imply different fates for C, and the same emergent CUE value can result when C is allocated in fundamentally different ways (e.g. a high investment in enzyme production vs. a high assimilation cost). We developed a model that represents the individual processes underlying emergent CUE to test how shifts in microbial allocation alter equilibrium soil C pool sizes. We found that an increase in emergent CUE that results from a change in assimilation efficiency, biomass specific respiration, or respiration costs from enzyme production causes soil organic C (SOC) to decline, while the same change in emergent CUE resulting from a change in enzyme production causes SOC to increase. We also used the model to test the sensitivity of CUE from isotopic C tracer estimates to changes in microbial allocation processes. We found that these estimates do not account for the same microbial processes represented by emergent CUE in models. We propose that considering microbial processes explicitly rather than representing CUE as a single parameter can improve data-model integration. In addition, modeling microbial processes explicitly will account for a wider range of possible outcomes from shifts in microbial C allocation, such as when increased SOC results from increasing CUE.     

低温木聚糖酶的研究进展

低温木聚糖酶在低温下仍具有较高酶活力及催化效率,在应用中能减少工艺流程,节省加热或冷却费用,降低耗能,有着中高温木聚糖酶无法比拟的优势。针对低温木聚糖酶的研究现状,包括来源、分子结构与适冷机制、基因工程及应用等方面进行综述。     

Reusable sensors in intrapartum foetal reflection pulse oximetry

OBJECTIVES: To evaluate the accuracy of intrapartum foetal pulse oximetry (SO(2POX)) using reusable sensors and the effect of a sensor performance test on data quality. Furthermore, to assess the sensor-related costs by using reusable sensors and sensor performance test. METHODS: 36 reusable sensors were used for SO(2POX) during labour of 289 term foetuses. A sensor performance test device assessing the emitter and receiver capability and the firmness of attachment of the sensors had been developed and used in the last 134 measurements before each resterilisation. Oxygen saturation (SaO(2)) at birth was measured spectrophotometrically after cord blood sampling. The accuracy of SO(2POX) was evaluated by analysing its relationship to SaO(2). The valid SO(2POX) data, as confirmed by subsequent sensor test in the second group, was considered comparable with those with single sensor use. Sensor-related average cost (sensors, test device and sterilisation) of such measurements was compared with that of single sensor use. RESULTS: Eight sensors failed performance test despite valid pulse oximetry signal output during their last measurements. There were significant overall linear correlations between SO(2POX) and SaO(2) (r=0.45, P<0.0001). Separate analyses of regression in the group without sensor performance testing showed an r(2) of 0.41, whereas in the group with subsequent sensor performance testing, the r(2) was 0.52 (P<0.05). By reusing the sensors, the sensor-related cost per valid measurement was $18.9 and 71% lower compared to single use of sensors ($65). CONCLUSIONS: Pulse oximetry may reflect fetal oxygen saturation. Data quality may be compromised by insufficient sensor performance, even though the reflection signal quality is acceptable. If sensor performance is tested before each measurement, reusable sensors may reduce the costs of fetal pulse oximetry.     

A HIGH THROUGHPUT SCREENING METHOD FOR 1,3-DIHYDROXYACETONE-PRODUCING BACTERIUM BY CULTIVATION IN A 96-WELL MICROTITER PLATE

1,3-Dihydroxyacetone (DHA) is used extensively in the cosmetic industry, and is the main active ingredient in all sunless tanning skincare preparation. In order to more efficiently and rapidly screen suitable strains or mutants for production of DHA, a high throughput screening method for DHA-producing bacterium by cultivation in a 96-well microtiter plate was developed. With this screening method, more than 100 strains that were able to convert glycerol to DHA were isolated from soil samples, and a mutant of Gluconobacter oxydans ZJB-605 that displayed the highest DHA productivity was obtained.

PRACTICAL APPLICATIONS

The practical application of this work is to promote the microbial process for isolating DHA-producing bacterium and screening DHA-overproducing mutant. With it, DHA manufactory can improve efficiency of strain operation, reduce labor and decrease production costs of DHA. It also can be used for reference about researches of glycerol dehydrogenase, and other alcohol dehydrogenase.     

Oscillometric instrument for the non-invasive detection of low-level microbial activity. Part 2: Growth characteristics, detection limits and impedimetric assays

Instrument performance and application was evaluated with a variety of microbial suspensions. Data were compared with those obtainable from current commercial apparatus in terms of resolution and detection times. Trials with growing and non-growing cultures indicated periodic synchronous ion exchange processes. Media composition, particularly salt and nutrient ratios, remain crucial to early and rapid detection of viable microbial activity at low concentrations. With appropriate conditions very significant improvements in detection times with typical detection thresholds of 300 min for start concentrations of 10(2) are shown. It is concluded that with regard to resolution and stability, the system out-performs current systems and is superior in terms of potential test costs, sample handling and sample transport.     

生物表面活性剂生产及应用研究进展

生物表面活性剂主要是由微生物代谢产生的,具有疏水基团和亲水基团的两亲性物质,它们能显著降低表面与界面张力。与化学表面活性剂相比,生物表面活性剂具有毒性低、生物兼容性好、可降解等优点,在众多领域具有良好的应用前景,但生物表面活性剂的高生产成本限制了商业化发展。本文旨在分析微生物表面活性剂的生产,重点是生产过程和代谢途径的优化,以探索产量与成本的关键因素,为生物表面活性剂商业化发展提供解决方案。     

低温纤维素酶的研究进展

低温纤维素酶在低温下仍具有较高酶活力及较高催化效率,在应用中能够缩短处理工艺时间,节省加热或冷却费用,且易失活,有着中高温纤维素酶无法比拟的优势。现针对微生物低温纤维素酶的研究现状,包括菌种来源、分离鉴定、酶学性质、适冷结构及机理研究和基因工程等方面进行综述。     

Desulfotomaculum and Methanobacterium spp. dominate a 4- to 5-kilometer-deep fault

Alkaline, sulfidic, 54 to 60 degrees C, 4 to 53 million-year-old meteoric water emanating from a borehole intersecting quartzite-hosted fractures >3.3 km beneath the surface supported a microbial community dominated by a bacterial species affiliated with Desulfotomaculum spp. and an archaeal species related to Methanobacterium spp. The geochemical homogeneity over the 650-m length of the borehole, the lack of dividing cells, and the absence of these microorganisms in mine service water support an indigenous origin for the microbial community. The coexistence of these two microorganisms is consistent with a limiting flux of inorganic carbon and SO4(2-) in the presence of high pH, high concentrations of H2 and CH4, and minimal free energy for autotrophic methanogenesis. Sulfide isotopic compositions were highly enriched, consistent with microbial SO4(2-) reduction under hydrologic isolation. An analogous microbial couple and similar abiogenic gas chemistry have been reported recently for hydrothermal carbonate vents of the Lost City near the Mid-Atlantic Ridge (D. S. Kelly et al., Science 307:1428-1434, 2005), suggesting that these features may be common to deep subsurface habitats (continental and marine) bearing this geochemical signature. The geochemical setting and microbial communities described here are notably different from microbial ecosystems reported for shallower continental subsurface environments.     

Microbial content of commercial South African high-moisture dried fruits

AIM: The aim was to evaluate commercially available South African high-moisture dried fruits (HMDF) for the microbial, moisture and SO2 contents, as well as aw and pH. METHODS AND RESULTS: The microbial content of commercially available HMDF was evaluated using nine different growth media. The moisture content, aw) SO2 and pH of each product were determined using standard analytical methods. It was found that the highest total aerobic counts were generated from high-moisture dried (HMD) prunes and raisins. The most frequent spoilers were members of the genus Bacillus. Fungal counts were also very high in the apricot products, exceeding the limit of 1000 CFU g(-1) as set by HMDF producers. Members of the genus Staphylococcus were found in the HMD raisins and Salmonella and thermoduric organisms were isolated from the HMD prunes. CONCLUSIONS: The microbial levels of South African HMDF were within the limits set, with the exception of apricots. SIGNIFICANCE AND IMPACT OF STUDY: The study shows the presence of Salmonella, Staphylococcus and Clostridium in South African HMDF. The presence of thermoduric organisms indicated that the current pasteurization process is not adequate and that the addition of preservatives would be an additional method to ensure safety and quality.