Extracellular matrix assembly in diatoms (bacillariophyceae).: V.: Environmental effects on polysaccharide synthesis in the model diatom, Phaeodactylum tricornutum
Extracellular matrix assembly in diatoms (bacillariophyceae).: V.: Environmental effects on polysaccharide synthesis in the model diatom, Phaeodactylum tricornutum
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DOI：
10.1111/j.1529-8817.2006.00193.x
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发表时间：
2006-04-01
影响因子：
2.9
通讯作者：
Gretz, MR
中科院分区：
文献类型：
--
作者：
Abdullahi, AS;Underwood, GJC;Gretz, MR
研究了磷酸盐（P）限制、不同盐度（5-65 psu）和固体培养基生长条件对三角褐指藻（Phaeodactylum tricornutum Bohlin）产多糖的影响。连续提取用于将聚合物分离成胶体（CL）、胶体胞外聚合物物质（cEPS）、热水可溶性（HW）、热碳酸氢盐可溶性（HB）和热碱（HA）可溶性级分。培养基可溶性聚合物（CL和cEPS）富含4-连接的甘露糖基、葡萄糖基和半乳糖基残基以及末端和3-连接的木糖基残基，而HW聚合物主要由3-连接的葡萄糖基以及末端和2，4-连接的葡萄糖醛酸残基组成。HB级分富含末端和2-连接的鼠李糖残基，这些残基来自通过这种处理溶解的粘液涂层。热碱处理导致硅藻壳完全溶解，释放2，3-和3-连接的甘露糖残基。梭形形态占主导地位的标准和P-有限的文化和文化进行盐度变化，但固体培养基上的生长导致的椭圆形形态的富集。15个残基的比例和连接，包括中性，糖醛酸，和O-甲基化糖，随环境条件而变化。磷限制和盐度的变化导致碳水化合物产量增加1.5至2.5倍，富含高度分支/取代和末端鼠李糖，木糖和岩藻糖以及O-甲基化糖，糖醛酸和硫酸盐。在不利的环境下，脱氧和O-甲基化糖含量的增加增强了聚合物的疏水性，而阴离子组分可能在离子交联中发挥重要作用，这表明这些变化可以改善盐度或P-应力的影响，这些改变的多糖特性可能是有用的环境应力的生物指示剂。
The effects of phosphate (P) limitation, varying salinity (5-65 psu), and solid media growth conditions on the polysaccharides produced by the model diatom, Phaeodactylum tricornutum Bohlin were determined. Sequential extraction was used to separate polymers into colloidal (CL), colloidal extracellular polymeric substances (cEPS), hot water soluble (HW), hot bicarbonate soluble (HB), and hot alkali (HA) soluble fractions. Media-soluble polymers (CL and cEPS) were enriched in 4-linked mannosyl, glucosyl, and galactosyl residues as well as terminal and 3-linked xylosyl residues, whereas HW polymers consisted mainly of 3-linked glucosyl as well as terminal and 2,4-linked glucuronosyl residues. The HB fraction was enriched in terminal and 2-linked rhamnosyl residues derived from the mucilage coating solubilized by this treatment. Hot alkali treatment resulted in the complete dissolution of the frustule releasing 2,3- and 3-linked mannosyl residues. The fusiform morphotype predominated in standard and P-limited cultures and cultures subjected to salinity variations, but growth on solid media resulted in an enrichment of the oval morphotype. The proportion and linkages of 15 residues, including neutral, uronic acid, and O-methylated sugars, varied with environmental conditions. P limitation and salinity changes resulted in 1.5- to 2.5-fold increase in carbohydrate production, with enrichment of highly branched/substituted and terminal rhamnose, xylose, and fucose as well as O-methylated sugars, uronic acids, and sulfate. The increased deoxy- and O-methylated sugar content under unfavorable environments enhances the hydrophobicity of the polymers, whereas the anionic components may play important roles in ionic cross-linking, suggesting that these changes could ameliorate the effects of salinity or P-stress and that these altered polysaccharide characteristics may be useful as bioindicators for environmental stress.