Reconstruction And Verification Of The Genome-scale Metabolic Model Of Bacillus Coagulans 36D1

Bacillus coagulans 36D1,a thermophilic and acid-tolerant bacterium,was potential for the fermentation of L-Lactic acid.Currently,the research on B.coagulans mainly unilaterally focused on the fermentation process or genetic modification,there was little comprehensive study of the intrinsic relationship between genes and metabolism.Firstly,a medium-size metabolic model of B.coagulans 36D1 was constructed to predict the necessary nutrients for B.coagulans growth and optimize the chemically defined medium through flux balance analysis,and found that chemically defined medium MCDM3++ containing folate and tyrosine could increase the high density growth of B.coagulans 36D1 and P4-102B by 163%and 73%,respectively,in comparison to its original medium MCDM3.And then,a genome-scale metabolic model(GSMM)was reconstructed based on the genome of B.coagulans 36D1 and verified with wet experiment.With Model SEED database and manual refinement,and verified by the experiment of 20 amino acid and 8 carbohydrate metabolism,a final GSMM including 672 genes,762 reactions and 673 metabolites was successfully built.The composition of biomass and its precursor was measured,and the content of protein,lipid,carbohydrate,DNA and RNA showed to be 45.75%?14.33?19.32%?8.29%?12.17%,respectively.The biomass equation was then used as the objective function of GSMM to predict specific growth rate using the specific consumption/production rates in MCDM3++under different dilution rate as constraints by FBA method.The result showed that the metabolic model displayed a well quality to predict the cellular phenotypes under different dilution rate.This study provided an important basis for the systematic study of B.coagulans metabolic regulation mechanism.