Smit G, Straver M H, Lugtenberg B J, Kijne J W
Institute of Molecular Plant Sciences, Leiden University, The Netherlands.
Appl Environ Microbiol. 1992 Nov;58(11):3709-14. doi: 10.1128/aem.58.11.3709-3714.1992.
Initiation of flocculation ability of Saccharomyces cerevisiae MPY1 cells was observed at the moment the cells stop dividing because of nitrogen limitation. A shift in concentration of the limiting nutrient resulted in a corresponding shift in cell division and initiation of flocculence. Other limitations also led to initiation of flocculence, with magnesium limitation as the exception. Magnesium-limited S. cerevisiae cells did not flocculate at any stage of growth. Cell surface hydrophobicity was found to be strongly correlated with the ability of the yeast cells to flocculate. Hydrophobicity sharply increased at the end of the logarithmic growth phase, shortly before initiation of flocculation ability. Treatments of cells which resulted in a decrease in hydrophobicity also yielded a decrease in flocculation ability. Similarly, the presence of polycations increased both hydrophobicity and the ability to flocculate. Magnesium-limited cells were found to be strongly affected in cell surface hydrophobicity. A proteinaceous cell surface factor(s) was identified as a flocculin. This heat-stable component had a strong emulsifying activity, and appears to be involved in both cell surface hydrophobicity and in flocculation ability of the yeast cells.
酿酒酵母MPY1细胞的絮凝能力在细胞因氮限制停止分裂时开始显现。限制营养物质浓度的变化导致细胞分裂和絮凝起始的相应变化。其他限制因素也会引发絮凝，但镁限制除外。镁限制条件下的酿酒酵母细胞在生长的任何阶段都不会絮凝。发现细胞表面疏水性与酵母细胞的絮凝能力密切相关。在对数生长期结束时，即絮凝能力开始显现前不久，疏水性急剧增加。导致疏水性降低的细胞处理方法也会使絮凝能力下降。同样，聚阳离子的存在会增加疏水性和絮凝能力。发现镁限制细胞的细胞表面疏水性受到强烈影响。一种蛋白质类细胞表面因子被鉴定为絮凝素。这种热稳定成分具有很强的乳化活性，似乎与酵母细胞的细胞表面疏水性和絮凝能力都有关。
