Partial Purification and Characterization of Extracellular Fructofuranosidase with Transfructosylating Activity from <Emphasis Type="Italic">Candida</Emphasis> sp.

The present work was carried out with the aim to investigate some properties of an extracellular fructofuranosidase enzyme, with high transfructosylating activity, from Candida sp. LEB-I3 (Laboratory of Bioprocess Engineering, Unicamp, Brazil). The enzyme was produced through fermentation, and after cell separation from the fermented medium, the enzyme was concentrated by ethanol precipitation and than purified by anion exchange chromatography. The enzyme exhibited both fructofuranosidase (FA) and fructosyltransferase (FTA) activities on a low and high sucrose concentration. With sucrose as the substrate, the data fitted the Michaellis–Menten model for FA, showing rather a substrate inhibitory shape for fructosyltransferase activity. The K _m and v _max values were shown to be 13.4 g L⁻¹ and 21.0 μmol mL⁻¹ min⁻¹ and 25.5 g L⁻¹ and 52.5 μmol mL⁻¹ min⁻¹ for FA and FTA activities, respectively. FTA presented an inhibitory factor K _i of 729.8 g L⁻¹. The optimum conditions for FA activity were found to be pH 3.25–3.5 and temperatures around 69 °C, while for FTA, the optimum condition were 65 °C (±2 °C) and pH 4.00 (±0.25). Both activities were very stable at temperatures below 60 °C, while for FA, the best stability occurred at pH 5.0 and for FTA at pH  4.5–5.0. Despite the strong fructofuranosidase activity, causing hydrolysis of the fructooligosaccharides (FOS), the high transfructosilating activity allows a high FOS production from sucrose (44%).     

海藻酸钠-微晶纤维素在SETR中包埋纳豆芽孢杆菌的固定化研究

目的 考察海藻酸钠-微晶纤维素在新型软弹式反应器(soft elastic tubular reactor, SETR)中对菌株的包埋作用。方法 使用海藻酸钠(sodium alginate, SA)与微晶纤维素(microcrystalline cellulose, MC)制成海藻酸钠-微晶纤维素水凝胶(microcrystalline cellulose/sodium alginate microcapsule, SA-MC)并包埋纳豆芽孢杆菌, 以光学显微镜形态、微球直径为指标, 单因素法优化SA与MC的配比和包埋时间; 并对优化好的SA-MC进行pH溶胀实验; 应用24 r/min的挤压频率进行发酵, 观察SA-MC在该过程中对pH的影响。结果 SA与MC以1:3的比例混合, 包埋时间1 h效果最佳; SA-MC对pH的响应并不敏感, 可用于发酵环境对菌株的包埋和保护; 与空白相比, SA-MC在SETR发酵环境中对pH有缓冲效果。结论 在SETR环境中SA-MC包埋纳豆芽孢杆菌表现较好的包埋作用。后续将进一步优化包埋材料的配方, 并对不同发酵参数的影响规律进行深入研究。本研究为天然材料包埋益生菌, 并旨在为SETR的应用推广提供理论支持。     

Reply to Fjell et al. (2010) and Raz and Lindenberger (2010): The prevalence of cortical gray matter atrophy may be overestimated in the healthy aging brain.

Burgmans et al. (2009) stated that the prevalence of cortical gray matter atrophy may be overestimated in the healthy aging brain, because the inclusion of participants with preclinical cognitive pathology might have been responsible for the age effects found in previous studies. Fjell et al. (2010) and Raz and Lindenberger (2010) verified this statement by reanalyzing previously published data. They both argue that it is unlikely that preclinical cognitive pathology explains cortical gray matter atrophy in healthy aging. Burgmans et al. (2010) respond to these commentaries. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimization of Trehalose Production by <Emphasis Type="Italic">Rhodotorula dairenensis</Emphasis> Following a Sequential Strategy of Experimental Design

Initially, a technical screening was applied to select yeasts with a potential for trehalose production using thermal stress for the induction of synthesis. The effects of the concentrations of sugar cane molasses, corn steep liquor and a commercial yeast extract Prodex Lac SD®, and of pH and temperature on the biomass were studied using a fractional design followed by a central composite rotatable design (CCRD). The optimum values were 50 g/l for the molasses and corn steep liquor concentrations, initial pH of 5.5, and temperature of 30 °C, with no yeast extract. Under these conditions, the production of trehalose was studied using a CCRD to optimize the temperature (33 to 47 °C) and exposition time (60 to 120 min) of the cultures to the thermal stress. The maximum intracellular trehalose content reached was 20.5% (g trehalose/100 g dry cell) at temperatures of 35–40 °C and with 100–120 min of exposition time to the thermal stress.     

Aging does not affect gray matter asymmetry.

Previous research has shown that asymmetry of brain activity is decreased in older adults. This study investigates whether cortical gray matter asymmetry also shows age-related differences, and whether gray matter asymmetry differs between cognitively stable persons and persons who have shown profound age-related declines in cognitive functioning. In addition, we have examined whether prodromal dementia affects the study outcome. The gray matter volumes of seven prefrontal and temporal regions of interest were delineated on T1-weighted MRI scans in 70 adults aged between 52 and 84 years. Statistical analyses were conducted with and without participants who developed dementia within 6 years after the MRI scan session. It was found that asymmetry did not differ over the age range of 52–84 years of age. This result did not change when data from participants who were diagnosed with dementia within 6 years after MRI assessment were excluded from the analysis. In addition, no gray matter asymmetry differences were found between cognitively stable participants and participants who showed cognitive decline. We conclude that alterations in gray matter asymmetry may not be part of the healthy aging process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parameter free shape and thickness optimisation considering stress response

In the parameter free approach, FE-based data are used as design variables, such as nodal coordinates and nodal thickness. During shape and thickness optimisation, this approach provides much design freedom for a limited modelling effort. Stress results are, however, very sensitive to the local shape changes that can occur during parameter free optimisation. When stress results are used as response function, this irregularity can complicate the optimisation. As a solution, the Kreisselmeier-Steinhauser function for the stresses is introduced as a response function for parameter free shape optimisation. In this function, the local stress results are aggregated to obtain a global measure of stress in a structure. This measure can be used as an objective to reduce the overall stress in the structure or as a constraint to limit the stress in the structure to a maximum allowable value. As a result, the optimal structures are smooth and material efficient. Several examples are presented in this paper to illustrate the use of the parameter free design approach in combination with the stress response function.     

Properties of thermostable extracellular FOS-producing fructofuranosidase from <Emphasis Type="Italic">Cryptococcus</Emphasis> sp.

The present work was devoted to investigations concerning the fructooligosaccharide producing activity of Cryptococcus sp. LEB-V2 (Laboratory of Bioprocess Engineering, Unicamp, Brazil) and its extracellular fructofuranosidase. After cell separation, the enzyme was purified by ethanol precipitation and anion exchange chromatography. The enzyme showed both fructofuranosidase (FA) and fructosyl transferase (FTA) activity. With sucrose as substrate, the data failed to fit the Michaelis–Menten behaviour, showing a substrate inhibitory model. The K _m, K _i and v _max values were shown to be 64 mM, 3 M and 159.6 μmol mL⁻¹ min⁻¹ for FA and 131 mM, 1.6 M and 377.8 μmol mL⁻¹ min⁻¹ for FTA, respectively. The optimum pH and temperature were found to be around 4.0 and 65 °C, while the best stability was achieved at pH 4.5 and temperatures below 60 °C, for both the FA and FTA. Despite the strong FA activity, the high transfructosylating activity allowed for good FOS production from sucrose (35% yield).     

Effektive Handhabung von Service-Informationen im Internet der Dienste

Business Webs apply the idea of value networks to the WWW. The underlying delivery platform is commonly referred to as the Internet of Services and will certainly have to deal with a great variety and amount of information about services along several service information dimensions. As soon as brokerage, discovery, or community feedback parts are decentralized, there emerge a number of service information challenges (modeling the information in a holistic way, documentation, interlinkage, tool interoperability, distributed querying, inconsistent information, and cooperation of different stakeholders). In this paper, we propose to counter such service information challenges by two artifacts. First, we contribute a Service Ontology based on a sound and rigid foundational ontology. The Service Ontology provides a holistic and consistent way of capturing service information. We apply the recommendations of the W3C Semantic Web Activity whose recent standardization has already opened new possibilities for tool interoperability, interlinkage of information, and distributed querying on the web. However, building and prescribing an ontology in standardized languages is not enough to address all service information challenges. Therefore, as a second contribution, we provide a method around the ontology including a governance framework, guidelines for applying the W3C Semantic Web recommendations, a lifecycle-spanning tool chain, and different levels of applicability. We label our method Semantic Business Web approach, since we build on W3C Semantic Web standards, use and extend them in the Business Web setting. Both artifacts are constructed in an interdisciplinary way by experts participating in the German lighthouse project THESEUS/TEXO. The project’s scenario also serves as a proof of concept evaluation of the artifacts.     

The prevalence of cortical gray matter atrophy may be overestimated in the healthy aging brain.

Prevailing opinion holds that normal brain aging is characterized by substantial atrophy of cortical gray matter. However, this conclusion is based on earlier studies whose findings may be influenced by the inclusion of subjects with subclinical cognitive disorders like preclinical dementia. The present magnetic resonance imaging study tested this hypothesis. Cognitively healthy subjects (mean age 72 years, range 52–82) who remained cognitively stable over a 3-year period were compared to subjects with significant cognitive decline. Subjects who developed dementia within 6 years after the scan session were excluded. The gray matter volumes of seven cortical regions were delineated on T1-weighted magnetic resonance imaging scans. Participants without cognitive decline did not exhibit an age effect on the gray matter volume. Conversely, participants with cognitive decline exhibited a significant age effect in all the seven areas. These results suggest that cortical gray matter atrophy may have been overestimated in studies on healthy aging, since most studies were unable to exclude participants with a substantial atypical cognitive decline or preclinical dementia. Our results underscore the importance of establishing stringent inclusion criteria for future studies on normal aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)