The roles of oxygen and alginate-lyase in determining the molecular weight of alginate produced by Azotobacter vinelandii
The roles of oxygen and alginate-lyase in determining the molecular weight of alginate produced by Azotobacter vinelandii
复制标题
DOI：
10.1007/s00253-003-1419-z
复制
发表时间：
2004-02
影响因子：
5
通讯作者：
M. Trujillo-Roldán;S. Moreno;G. Espín;E. Galindo
中科院分区：
文献类型：
--
作者：
M. Trujillo-Roldán;S. Moreno;G. Espín;E. Galindo
缺乏藻酸盐裂解酶的葡萄固氮菌突变体 (SML2) 和野生型 (ATCC 9046) 用于区分聚合酶复合物和藻酸盐裂解酶在受控溶解氧张力 (DOT) 培养物中藻酸盐合成中的作用。为了避免预合成的藻酸盐的存在，所有培养物都用洗涤的细胞接种。对于使用突变体在 3% DOT 下进行的培养，获得了明确的高平均分子量 (MMW) 藻酸盐家族 (985 kDa)。在 1% 和 5% DOT 下，突变体产生了具有较低 MMW（150 和 388 kDa）的独特藻酸盐家族。使用野生型观察到类似的行为：在 3% DOT (1,250 kDa) 时产生明确的海藻酸盐家族，在 1% 和 5% DOT (370 和 350 kDa) 时产生较低毫米波。在 ATCC 9046 发酵结束时，藻酸盐通过裂合酶的作用解聚。总体而言，证据表明海藻酸盐的聚合是通过产生窄 MMW 范围内的多糖家族来进行的，并且高度依赖于 DOT。海藻酸裂解酶（存在于野生型中）的作用仅限于聚合后步骤。
AnAzotobacter vinelandiimutant lacking alginate-lyase (SML2) and the wild type (ATCC 9046) were used to discriminate between the roles of the polymerase complex and alginate-lyase in the synthesis of alginate in cultures conducted under controlled dissolved oxygen tension (DOT). To avoid the presence of pre-synthesized alginates, all cultures were inoculated with washed cells. For cultures carried out at 3% DOT using the mutant, a well defined family of alginates of high mean molecular weight (MMW) were obtained (985 kDa). Under 1% and 5% DOT, the mutant produced unique families of alginates with lower MMW (150 and 388 kDa). A similar behavior was observed using the wild type: a production of well defined families of alginates of high MMW at 3% DOT (1,250 kDa) and lower MMW at 1% and 5% DOT (370 and 350 kDa). At the end of the ATCC 9046 fermentations, alginate was depolymerized by the action of lyases. Overall, the evidence indicated that polymerization of alginate is carried out by producing families of polysaccharide in a narrow MMW range, and that it is highly dependent on DOT. The role of alginate-lyase (present in the wild type) is restricted to a post-polymerization step.