Metabolite profiles and growth characteristics of Rhizobium meliloti cultivated at different specific growth rates.
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).
Ong
Lay Ching
LC
Department of Chemical Engineering, University of Saskatchewan, Research Annex, 105 Maintenance Road, Saskatoon, SK Canada S7N 5C5.
Lin
Yen-Han
YH
D001426:Bacterial Proteins / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D002455:Cell Division / Q000502:physiology; D008970:Molecular Weight; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000378:metabolism*; D016962:Sinorhizobium meliloti / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure
D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial