葛仙米生长的尺度效应

为考察葛仙米(Nostoc sphaeroides)群体粒径变化对营养成分和光合活性的影响, 测定了生长过程中不同粒径群体的色素成分、光合特性和多糖含量。结果表明: 叶绿素a、藻胆蛋白含量随群体粒径增大而降低; 类胡萝卜素含量在粒径4.85 mm时最高, 藻蓝蛋白/叶绿素a、藻红蛋白/叶绿素a以及别藻蓝蛋白/叶绿素a的比值随粒径增大先降低后升高; 最大潜在光合能力(F_v/F_m)随群体粒径增大逐渐降低, 大群体可通过光系统I介导的环式电子传递链耗散多余能量以保护光合作用系统; 多糖含量在粒径3.03 mm时最高。研究结果显示葛仙米生长具有明显的尺度效应, 细胞组分与光合活性对群体粒径变化具有显著的响应, 开展规模化培养和采收需要关注这一效应。

THE SIZE EFFECTS OF NOSTOC SPHAEROIDES DURING ITS GROWTH

This study investigated nutrients component, photosynthetic activities, pigments components, polysaccha-ride contents and photosynthetic activities during the colony size variation ofNostoc sphaeroides. The result showed that the content of chlorophyll a and phycobiliprotein decreased with increased colony particle size. The maximum con-tent of carotenoid was occurred in colonies with particle size 4.85 mm; the phycobiliprotein contents was the highest in colonies with particle size 0.77 mm; the maximum content of polysaccharide was occurred in colonies with particle size 3.03 mm; the proportion of phycocyanin/chlorophyll a, phycoerythrin/chlorophyll a and allophycocyanin first in-creased and then decreased with the enhanced colony particle size; the maximum potential photosynthetic capacity (Fv/Fm) reduced with the increase of colony particle size. Colonies with smaller size were more tolerant to high light in-tensity than larger ones, and the high rate of cyclic electron transport of the colonies with large particle size can dissi-pate excess energy to counter the damage caused by the high light. The growth ofNostoc sphaeroides shows size effect and the cell component and photosynthetic activities mediate colony size variation, which are important to concern the mass of start culture and the harvest time ofNostoc sphaeroides.