生物絮凝的外文资料

linjunyue1

生物絮凝方面的外文资料

bushiyinweijimo

最好翻译过来上传，。

fengzizt

REVIEW ARTICLE Flocculation in Saccharomyces cerevisiae: a review E.V. Soares1,2 1 Bioengineering Laboratory, Chemical Engineering Department, Superior Institute of Engineering from Porto Polytechnic Institute, Rua Dr Anto nio Bernardino de Almeida, Porto, Portugal 2 IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, Braga, Portugal Introduction Yeast flocculation can be defined as a nonsexual, homotypic (involving only one type of cell in the interactions), reversible (flocs can be reversible dispersed by the action of EDTA or specific sugars, like mannose) and multivalent process of aggregation of yeast cells into multicellular masses (composed by thousands or even millions of cells), called flocs, with the subsequent rapid sedimentation from the medium in which they are suspended (Fig. 1) (Stratford 1992b; Stewart 2009). The word floc derives from the Latin word floccus, which means a tuft of wool. The cells with the ability to form flocs are called flocculants and look like tufts of wool (Fig. 1a), while the cells that are not able to form flocs are usually known as powdery. Saccharomyces cerevisiae cells can be found aggregated in different ways, which should not be confused with flocculation, such as sexual aggregation, co-flocculation and chain formation. Sexual aggregation in haploid strains of S. cerevisiae of complementary mating types (a and a) can occur after exchange of pheromones a and a, respectively, which induces the appearance of complementary molecules (proteins) on surface of cells and facilitates the fusion of the haploid cells (Chen et al. 2007). Co-flocculation or mutual flocculation is a heterotypic aggregation process (while flocculation is homotypic) among two strains: one of them is nonflocculent and the other weakly flocculent; when mixed, in the presence of Ca2+, the strains rapidly settle (Stewart 2009). Chain formation occurs because of a failure of the younger bud to separate from the mother cell; this results in an aggregate formation composed of 30–50 cells. These aggregates are covalently linked; thus, after mechanical dispersion, cells will not be able to re-aggregate (Stewart 2009). Other aggregation phenomena in S. cerevisiae include biofilm (Verstrepen et al. 2004) and pseudohyphae formation, which grow and invade the agar medium (Gimeno et al. 1992). Saccharomyces sensu stricto complex had a long and profitable association with food, biotechnology and pharmaceutical industries; it is the micro-organism most industrially exploited by the man (Vaughan-Martini and Keywords aggregation, alcoholic beverages, bio-ethanol, brewing yeast, cell separation, FLO genes, flocculation. Correspondence Soares Eduardo, Bioengineering Laboratory, Chemical Engineering Department, Superior Institute of Engineering from Porto Polytechnic Institute, Rua Dr Anto nio Bernardino de Almeida, 431, 4200-072 Porto, Portugal. E-mail: evs@isep.ipp.pt 2010 0514: received 27 April 2010, revised and accepted 26 October 2010. doi:10.1111/j.1365-2672.2010.04897.x Summary The present work reviews and critically discusses the aspects that influence yeast flocculation, namely the chemical characteristics of the medium (pH and the presence of bivalent ions), fermentation conditions (oxygen, sugars, growth temperature and ethanol concentration) and the expression of specific genes such as FLO1, Lg-FLO1, FLO5, FLO8, FLO9 and FLO10. In addition, the metabolic control of loss and onset of flocculation is reviewed and updated. Flocculation has been traditionally used in brewing production as an easy and off-cost cell-broth separation process. The advantages of using flocculent yeast strains in the production of other alcoholic beverages (wine, cachac愀 and sparkling wine), in the production of renewal fuels (bio-eth

fengzizt

分别为 1楼 2楼 的简单截图 我是看不懂

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Flocculation onset in Saccharomyces cerevisiae: the role of nutrients S. Sampermans1,3, J. Mortier2,3 and E.V. Soares3 1KHLim, Departement Industriele Wetenschappen en Technologie, Universitaire Campus, Gebouw B, Diepenbeek, Belgium, 2KaHo St- Lieven, Industrial Engineering, Department of Biochemistry–Microbiology, Gebroeders Desmetstraat 1, Gent, Belgium, and 3CIEADepartamento de Engenharia Qu洀椀挀愀, Instituto Superior de Engenharia do Instituto Polite挀渀椀挀漀 do Porto, Rua Dr Anto渀椀漀 Bernardino de Almeida, Porto, Portugal 2004/0776: received 6 July 2004, revised 27 September 2004 and accepted 27 September 2004 ABSTRACT S. SAMPERMANS, J. MORTIER AND E.V. SOARES. 2004. Aims: To examine the role of the nutrients on the onset of flocculation in an ale-brewing strain, Saccharomyces cerevisiae NCYC 1195. Methods and Results: Flocculation was evaluated using the method of Soares, E.V. and Vroman, A. [Journal of Applied Microbiology (2003) 95, 325]. For cells grown in chemically defined medium (yeast nitrogen base with glucose) or in rich medium (containing yeast extract, peptone and fermentable sugars: fructose or maltose), the onset of flocculation occurred after the end of exponential respiro-fermentative phase of growth being coincident with the attainment of the lower level of carbon source in the culture medium. Cells, in exponential respiro-fermentative phase of growth, transferred to a glucose-containing medium without nitrogen source, developed a flocculent phenotype, while these carbon source starved cells, in the presence of all other nutrients that support growth, did not flocculate. In addition, cells in exponential phase of growth, under catabolite repression, when transferred to a medium containing 02% (w/v) of fermentable sugar (fructose or maltose) or 2% (v/v) ethanol, showed a rapid triggering of flocculation, while when incubated in 2% (v/v) glycerol did not develop a flocculent phenotype. Conclusions: The onset of flocculation occurs when a low sugar and/or nitrogen concentration is reached in culture media. The triggering of flocculation is an energetic dependent process influenced by the carbon source metabolism. The presence of external nitrogen source is not necessary for developing a flocculent phenotype. Significance and Impact of the Study: This work contributes to the elucidation of the role of nutrients on the onset of flocculation in NewFlo phenotype yeast strains. This information might be useful to the brewing industry, in the control of yeast flocculation, as the time when the onset of flocculation occurs c

linjunyue1

生物絮凝方面的资料

freeaswind

这个怎么看得懂哦，，