Title
Integrating Flux Balance Analysis Into Kinetic Models To Decipher The Dynamic Metabolism Of Shewanella Oneidensis Mr-1
Abstract
Shewanella oneidensis MR-1 sequentially utilizes lactate and its waste products (pyruvate and acetate) during batch culture. To decipher MR-1 metabolism, we integrated genome-scale flux balance analysis (FBA) into a multiple-substrate Monod model to perform the dynamic flux balance analysis (dFBA). The dFBA employed a static optimization approach (SOA) by dividing the batch time into small intervals (i.e. similar to 400 mini-FBAs), then the Monod model provided time-dependent inflow/outflow fluxes to constrain the mini-FBAs to profile the pseudo-steady-state fluxes in each time interval. The mini-FBAs used a dual-objective function (a weighted combination of "maximizing growth rate" and "minimizing overall flux") to capture trade-offs between optimal growth and minimal enzyme usage. By fitting the experimental data, a bi-level optimization of dFBA revealed that the optimal weight in the dual-objective function was time-dependent: the objective function was constant in the early growth stage, while the functional weight of minimal enzyme usage increased significantly when lactate became scarce. The dFBA profiled biologically meaningful dynamic MR-1 metabolisms: 1. the oxidative TCA cycle fluxes increased initially and then decreased in the late growth stage; 2. fluxes in the pentose phosphate pathway and gluconeogenesis were stable in the exponential growth period; and 3. the glyoxylate shunt was up-regulated when acetate became the main carbon source for MR-1 growth.
Year
DOI
Venue
2012
10.1371/journal.pcbi.1002376
PLOS COMPUTATIONAL BIOLOGY
Keywords
Field
DocType
citric acid cycle,exponential growth,objective function,pentose phosphate pathway,flux balance analysis,kinetics,systems biology,carbon isotopes,steady state,enzyme,gluconeogenesis
Biology,Biological system,Biochemistry,Shewanella oneidensis,Glyoxylate cycle,Gluconeogenesis,Shewanella,Genetics,Pyruvic acid,Growth rate,Flux balance analysis,Exponential growth
Journal
Volume
Issue
ISSN
8
2
1553-7358
Citations 
PageRank 
References 
9
0.66
2
Authors
4
Name
Order
Citations
PageRank
Xueyang Feng1171.12
You Xu224610.63
Yixin Chen34326299.19
Yinjie J Tang4171.80