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排序方式: 共有110条查询结果,搜索用时 31 毫秒
41.
Joël Fleurence Catherine Le Coeur Serge Mabeau Manuelle Maurice Annie Landrein 《Journal of applied phycology》1995,7(6):577-582
Proteins have been extracted from the edible seaweeds Ulva rigida Agardh and Ulva rotundata Bliding using classical or enzymatic procedures. The protocols using NaOH under reductive conditions or a two-phase system (PEG/K2CO3) produced the best protein yields. The cleavage or the limitation of the linkages between proteins and polysaccharides caused by these experimental conditions probably explains the efficiency of these protocols. In SDS PAGE, the protein fraction obtained after NaOH extraction from U. rotundata is characterised by the presence of three major bands with apparent molecular weights of 45 600, 31 800 and 18 600. The protein fraction from U. rigida presents two specific bands with apparent molecular weights of about 27 000 and 12 000. These fractions are mainly rich in aspartic and glutamic acids, alanine, glycine and contain few hydroxyproline residues (0.91–2.44% total amino acid content). The use of cellulase does not significantly improve the extraction of algal proteins in comparison with the blank procedure (without enzymes). The weak accessibility of the substrates in the intact cell wall could explain these experimental data. The improvement of protein yield after the use of the polysaccharidase mixture (-glucanase, hemicellulase, cellulase) partially confirms this hypothesis. 相似文献
42.
Interpopulation variability in patterns of food processing, similar to what is described as "traditional" or "cultural" variation in chimpanzees (Pan troglodytes) and orangutans (Pongo pygmaeus), was identified in white-faced capuchins (Cebus capucinus). However, recent comparisons of food processing in capuchins were conducted only at the population level, with relatively little attention given to variability among groups, age/sex classes, or individuals. This paper examines variability in the processing of specific food types within the context of various social networks (i.e., patterns of association, rank, and kinship) among free-ranging Cebus capucinus at Santa Rosa National Park in Costa Rica. We collected data on two groups of white-faced capuchins in 2001, identifying rates of "food interest" for each individual, as well as forms of processing for specific food types. Juveniles exhibited the most interest in the food-processing behavior of other group members, and food interest was directed most frequently toward adult females. We identified distinctive processing techniques for several food items (Luehea candida pods, Sloanea terniflora fruits, and caterpillars) that facilitated comparisons among individuals within groups. Food-processing techniques for Sloanea fruit and caterpillars appeared to vary independently of the social networks examined in this study. However, we found evidence that variation in Luehea candida processing is to some degree linked to both patterns of association and social rank. The potential influence of these variables on observed food processing patterns warrants further scrutiny. 相似文献
43.
Observed patterns of variability in the food-processing behavior of white-faced capuchins (Cebus capucinus) across populations may reflect foraging traditions. However, there has been relatively little attention given to intrapopulation variability in food processing among groups and age/sex classes, making recent cross-population comparisons difficult to interpret. In this paper, we provide data on patterns of object use in foraging that we observed at Santa Rosa National Park, Costa Rica, for comparison with published data from a neighboring research site, Palo Verde National Park. We also describe the techniques used to process two food items consumed by Cebus capucinus at Santa Rosa, and discuss the factors that may underlie observed variability. We conducted a 6-month study on two groups of capuchins in 2001, and collected data on general activity and feeding patterns, rates and forms of object use, and distinctive processing techniques employed for two specific foods (Sloanea terniflora and Luehea candida). Rates of object-use behavior at Santa Rosa were considerably higher than those reported for Palo Verde and showed significant variation between groups and age/sex classes, as did patterns of Sloanea and Luehea processing. Observed differences in feeding rates between groups may reflect food availability or relative profitability, whereas variation between age/sex classes seems to reflect differences in the physical capabilities, foraging strategies, and the relative experience of mature and immature animals. Further research is needed to identify how a social context may influence the acquisition of food-processing techniques in juveniles and the development of foraging traditions in social groups. 相似文献
44.
Rhizoctonia solani, an elicitor of 6-pentyl-α-pyrone production by Trichoderma harzianum in a two liquid phases, extractive fermentation system 总被引:1,自引:0,他引:1
6-pentyl-alpha-pyrone (6PP) production by Trichoderma harzianum, in an extractive fermentation system, was elicitated by Rhizoctonia solani. The extent of 6PP elicitation was related to the state of Rhizoctonia and to the Trichoderma inoculum type. The use of non-viable Rhizoctonia solani mycelium in mycelium-inoculated Trichoderma harzianum culture, yielded the maximal 6PP production (474 mg l(-1)) compared to control cultures (147 mg l(-1)) and decreased the process time from 192 to 96 h. 相似文献
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46.
Membrane-attached biofilms for VOC wastewater treatment. II: Effect of biofilm thickness on performance 总被引:1,自引:0,他引:1
This article reports a study of the performance of membrane-attached biofilms grown in a single tube extractive membrane bioreactor (STEMS) used for the treatment of a synthetic wastewater containing a toxic VOC (1,2-dichloroethane [DCE]). Mass balances show that complete mineralization of DCE was achieved, and that the biofilms were effective in reducing air stripping to negligible levels. Experimental results are presented showing the evolution over time of biofilm thickness and its influence on the flux of DCE across the membrane. It has been found that a trade-off exists between the positive influence of biofilms in reducing air-stripping of DCE, and the negative influence of biofilms in reducing DCE flux across the membrane. These considerations lead to an optimal biofilm thickness in the region of 200 to 400 mum being recommended for this system. (c) 1995 John Wiley & Sons, Inc. 相似文献
47.
The partitioning of pristinamycins was studied in dextran and polyethylene glycol (PEG) aqueous two-phases systems. Pristinamycins partitioned preferentially into the PEG-rich top phase. The partition coefficient was independent of molar mass of PEG and dextran and of antibiotic concentration, but, increased exponentially with the tieline length of the system. Partition of pristinamycins was greatly improved when fatty acids esters of PEG were mixed with PEG. In such mixtures, the partition of coefficient increased up to a value of 24, dependent on the carbon chain length of fatty acids and the modified PEG concentrations. Moreover, in such system, the two groups of pristinamycins, I and II, were extracted in accordance with their hydrophobicity. Recovery of pristinanamycins produced by Streptomyces pritinaespiralis in a fermentation broth was achieved with a dextran/PEG system. Cells were confined into the bottom phase and pristinamycins partitioned in the top phase. However, due to binding of the pristinamycins to the cells, the partition coefficient was slightly lower than of pure antibiotics solutions. (c) 1994 John Wiley & Sons, Inc. 相似文献
48.
Effect of aeration and agitation on extractive fermentation of clavulanic acid by using aqueous two‐phase system
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Daniela A. Viana Marques Valéria C. Santos‐Ebinuma Adalberto Pessoa‐Júnior Ana L. F. Porto Beatriz Rivas Torres Attilio Converti 《Biotechnology progress》2016,32(6):1444-1452
In this work, the effects of agitation and aeration rates on aqueous two‐phase system (ATPS)‐based extractive fermentation of clavulanic acid (CA) by Streptomyces variabilis DAUFPE 3060 were investigated through a 22 full factorial design, where oxygen transfer rate (OTR) and oxygen uptake rate (OUR) were selected as the responses. Aeration rates significantly influenced cell growth, OUR, and CA yield, while OTR was practically the same in all the runs. Under the intermediate agitation (950 rpm) and aeration conditions (3.5 vvm) of the central point runs, it was achieved OTR of 1.617 ± 0.049 mmol L?1 h?1, OUR of 0.132 ± 0.030 mmol L?1 h?1, maximum CA production of 434 ± 4 mg L?1, oxygen mass transfer coefficient of 33.40 ± 2.01 s?1, partition coefficient of 66.5 ± 1.5, CA yield in the top and bottom phases of 75% ± 2% and 19% ± 1%, respectively, mass balance of 95% ± 4% and purification factor of 3.8 ± 0.1. These results not only confirmed the paramount role of O2 supply, broth composition and operational conditions in CA ATPS‐extractive fermentation, but also demonstrated the possibility of effectively using this technology as a cheap tool to simultaneously produce and recover CA. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1444–1452, 2016 相似文献
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50.
《Critical reviews in biotechnology》2013,33(4):345-364
Worldwide interest in prebiotics have been increasing extensively both as food ingredients and pharmacological supplements, since they have beneficial properties for human health. Prebiotics not only stimulate the growth of healthy bacteria such as bifidobacteria and lactobacilli in the gut but also increase the resistance towards pathogens. In addition to this, they also act as dietary fiber, an energy source for intestinal cells after converting to short-chain fatty acids, a stimulator of immune systems, sugar replacer etc. Moreover, due to heat resistant properties, they are able to maintain their intact form during the baking process and allow them to be incorporated into every day food products. Thus, they can be interesting and useful ingredients in the development of novel functional foods. This review provides comprehensive information about the different biotechnological techniques employed in the production of prebiotics and their potential applications in different areas. 相似文献