Elementary mode analysis is a useful metabolic pathway analysis tool in understanding and analyzing cellular metabolism, since elementary modes can represent metabolic pathways with unique and minimal sets of enzyme-catalyzed reactions of a metabolic network under steady state conditions. However, computation of the elementary modes of a genome-scale metabolic network with 100-1000 reactions is very expensive and sometimes not feasible with the commonly used serial Nullspace Algorithm. In this work, we develop a distributed memory parallelization of the Nullspace Algorithm to handle efficiently the computation of the elementary modes of a large metabolic network. We give an implementation in C++ language with the support of MPI library functions for the parallel communication. Our proposed algorithm is accompanied with an analysis of the complexity and identification of major bottlenecks during computation of all possible pathways of a large metabolic network. The algorithm includes methods to achieve load balancing among the compute-nodes and specific communication patterns to reduce the communication overhead and improve efficiency.
Bibliographical noteFunding Information:
This work was partially supported by NIH Grant GM077529 , NSF Grants 0534286 and 0916750 and by the Biomedical Informatics and Computational Biology Program of the University of Minnesota, Rochester . We are grateful for resources and technical support from the University of Minnesota Supercomputing Institute, and would like to thank Can Ergenikan, David Poter and Shuxia Zhang for their help. We also thank the IBM Rochester Blue Gene Center, Cindy Mestad and Steven Westerbeck for their support. Finally, we thank Palsson’s Lab for the access to BiGG database of genome-scale metabolic networks. Appendix A
- Biochemical network
- Elementary flux mode
- Metabolic pathway
- Nullspace Algorithm