1
We retrieved PATHNET data, a prior reconstruction of the
H. salinarum metabolic network based on Kyoto Encyclopedia
of Genes and Genomes (KEGG) defined pathways,58 from the
Halolex database. We used this as the starting point for
further reconstruction using literature review and bioinfor-
matic means. The evidences used for the inclusion of reactions/
enzymes to the network include enzymatic assays, labeling
studies, and nutrient uptake reports (for transporters).
Reactions described by such references were included with or
without genetic evidence. Similarly, pathway gaps and reac-
tions devoid of literature or genetic indicators but required by
the network to produce a compound essential for growth
were also added. In cases where detailed information on
H. salinarum R-1 were unavailable, data from various strains
 of Halobacterium salinarum were used. Likewise, reaction
reversibilities were also taken from literature sources whenever
available. Particularly helpful in this regard was the BRENDA
database,59 which, among other things, stores reversibility
information from various organisms. 