Ong Lay Ching, Lin Yen-Han
Department of Chemical Engineering, University of Saskatchewan, Research Annex, 105 Maintenance Road, Saskatoon, SK Canada S7N 5C5.
Biotechnol Prog. 2003 May-Jun;19(3):714-9. doi: 10.1021/bp025758w.
Rhizobium meliloti (ATCC 55340) was grown at different specific growth rates in a chemostat apparatus. Metabolic products, relating to the Embden-Meyerhof-Parnas (EMP) pathway and the tricarboxylic acid (TCA) cycle, were measured and quantified to probe the influence of specific growth rate on the distribution of important metabolites. The detection of propionate in the fermentation broth implies that the imbalance of reducing equivalents of FADH(2) and NADH + H(+) resulted in a partially reductive operation of the TCA cycle. Additionally, experimental results show that the specific growth rate plays an essential role in modulating the biomass concentration, the specific substrate uptake rate, the cell length, the specific exopolysaccharide (EPS) production rate, the distribution of EPS molecular weight, and the profiles of carbohydrate and organic acid. The specific EPS production rate (varying from 13.3 to 111 mg EPS/g-DW/h) follows a growth-associated pattern at the specific growth rate ranging from 0.06 to 0.20 h(-1) and switches into non-growth-associated mode when the specific growth rate is over 0.20 h(-1).
苜蓿中华根瘤菌（ATCC 55340）在恒化器装置中以不同的比生长速率进行培养。对与糖酵解途径和三羧酸（TCA）循环相关的代谢产物进行了测定和定量，以探究比生长速率对重要代谢物分布的影响。发酵液中丙酸盐的检测表明，FADH₂和NADH + H⁺还原当量的不平衡导致了TCA循环的部分还原运行。此外，实验结果表明，比生长速率在调节生物量浓度、比底物摄取速率、细胞长度、比胞外多糖（EPS）产生速率、EPS分子量分布以及碳水化合物和有机酸谱方面起着至关重要的作用。比EPS产生速率（从13.3到111 mg EPS/g-DW/h不等）在比生长速率为0.06至0.20 h⁻¹范围内遵循生长关联模式，当比生长速率超过0.20 h⁻¹时转变为非生长关联模式。
