Shishlyannikov Sergey M, Klimenkov Igor V, Bedoshvili Yekaterina D, Mikhailov Ivan S, Gorshkov Alexander G
Limnological Institute, Siberian Branch, Russian Academy of Sciences, 3, Ulan-Batorskaya, St, P.O. Box 278, Irkutsk, 664033 Russia.
J Biol Res (Thessalon). 2014 Aug 4;21(1):15. doi: 10.1186/2241-5793-21-15. eCollection 2014 Dec.
Interest in studies concerning the effect of organic carbon sources on the growth of diatoms is largely aimed at subsequent physiological changes occurring in their cells. There are no data on structural changes in the cytoplasm and their relationship with changes in the composition of fatty acids in the course of mixotrophic culturing of freshwater diatoms. To elucidate the role of lipids in the growth of diatom cells in autotrophic and mixotrophic cultures, it is necessary to obtain information on the distribution of fatty acids among intracellular compartments and on possible ultrastructural changes in the cells.
In this study, the results demonstrated that Synedra acus cells cultured in the presence of 80 mM glycerol contained lipid bodies of increased size, while cells from cultures supplemented with 40 mM glucose accumulated polysaccharide (chrysolaminarin) granules. An increase in the relative amounts of palmitic and stearic acids was revealed at the exponential growth phase of S. acus in the medium with 80 mM glycerol, which was indicative of the accumulation of fatty acids contained in triacylglycerols.
Synedra acus subsp. radians have an ability to proliferate in the presence of high concentrations of organic substances and their transport into cells is evidence for its high adaptation potential, which, along with other factors, accounts for the dominance of this diatom in the spring-summer plankton of the oligotrophic Lake Baikal.
关于有机碳源对硅藻生长影响的研究兴趣主要集中在其细胞随后发生的生理变化上。目前尚无关于淡水硅藻混合营养培养过程中细胞质结构变化及其与脂肪酸组成变化关系的数据。为了阐明脂质在自养和混合营养培养的硅藻细胞生长中的作用，有必要获取脂肪酸在细胞内各部分的分布信息以及细胞可能发生的超微结构变化信息。
在本研究中，结果表明，在含有80 mM甘油的条件下培养的针杆藻细胞含有尺寸增大的脂质体，而在补充有40 mM葡萄糖的培养物中的细胞积累了多糖（金藻昆布多糖）颗粒。在含有80 mM甘油的培养基中，针杆藻指数生长期棕榈酸和硬脂酸的相对含量增加，这表明三酰甘油中所含脂肪酸的积累。
辐射针杆藻亚种有能力在高浓度有机物质存在的情况下增殖，并且它们向细胞内的运输证明了其高适应潜力，这与其他因素一起，解释了这种硅藻在贫营养的贝加尔湖春夏浮游生物中的优势地位。
