Specific growth rate dependent transcriptome profiling of Escherichia coli K12 MG1655 in accelerostat cultures
Specific growth rate dependent transcriptome profiling of Escherichia coli K12 MG1655 in accelerostat cultures
复制标题
DOI：
10.1016/j.jbiotec.2009.10.007
复制
发表时间：
2010-01-01
影响因子：
4.1
通讯作者：
Vilu, Raivo
中科院分区：
文献类型：
--
作者：
Nahku, Ranno;Valgepea, Kaspar;Vilu, Raivo
采用芯片技术和实时PCR技术研究了大肠杆菌K12 MG1655特定生长速率依赖性基因表达的变化。细菌在葡萄糖限制的最小培养基上使用加速法（A-stat）培养，从稳态条件（趋化培养）开始，稀释率不断增加。在特定生长速率（mu）为0.47 h（-1）时，与mu = 0.3 h（-1）相比，大肠杆菌通过下调替代底物转运体的表达，将代谢集中在葡萄糖利用上。结果发现，乙酸的积累始于mu = 0.34 +/- 0.01 h(-1)，在溢出代谢开始即醋酸排泄开始时，磷酸转乙酰酶-醋酸激酶（pta-ackA）和丙酮酸氧化酶（poxB）两条醋酸合成途径参与了乙酸的合成。另一方面，poxB、pta和ackA的表达谱表明，在mu = 0.47 h（-1）时，丙酮酸氧化酶可能是唯一合成醋酸酯的酶。以acs-yjcH-actPoperon在0.3-0.42 h（-1）之间的特定生长速率下调为代表的葡萄糖和乙酸共利用的丧失，以及从mu = 0.34 0.01 h（-1）开始的乙酸积累，可以推测乙酸利用操纵子的表达可能在溢出代谢中起重要作用。(c) 2009 Elsevier B.V.版权所有
Specific growth rate dependent gene expression changes of Escherichia coli K12 MG1655 were studied by microarray and real-time PCR analyses. The bacteria were cultivated on glucose limited minimal medium using the accelerostat method (A-stat) where starting from steady state conditions (chemostat culture) dilution rate is constantly increased. At specific growth rate (mu) 0.47 h(-1), E coli had focused its metabolism to glucose utilization by down-regulation of alternative substrate transporters expression compared to mu = 0.3 h(-1). It was found that acetic acid accumulation began at mu = 0.34 +/- 0.01 h(-1) and two acetate synthesis pathways - phosphotransacetylase-acetate kinase (pta-ackA) and pyruvate oxidase (poxB) - contributed to the synthesis at the beginning of overflow metabolism, i.e. onset of acetate excretion. On the other hand, poxB, pta and ackA expression patterns suggest that pyruvate oxidase may be the only enzyme synthesizing acetate at mu = 0.47 h(-1). Loss of glucose and acetate co-utilization represented by down-regulation of acs-yjcH-actPoperon between specific growth rates 0.3-0.42 h(-1) and acetic acid accumulation from mu = 0.34 0.01 h(-1) allows one to surmise that the acetate utilization operon expression might play an important role in overflow metabolism. (c) 2009 Elsevier B.V. All rights reserved.