The Scr and Csc pathways for sucrose utilization co-exist in , but only the Scr pathway is widespread in other .

Most isolates from humans do not utilize D-sucrose as a substrate for fermentation or growth. Previous work has shown that the Csc pathway allows some to utilize sucrose for slow growth, and this pathway has been engineered in W strains to enhance use of sucrose as a feedstock for industrial applications. An alternative sucrose utilization pathway, Scr, was first identified in and has been reported in some and isolates. We show here that the Scr pathway is native to an important subset of phylogroup B2 lineages that lack the Csc pathway but grow rapidly on sucrose. Laboratory strains derived from MG1655 (phylogroup A, ST10) are unable to utilize sucrose and lack the and genes, but a recombinant plasmid-borne locus enables rapid growth on and fermentation of sucrose. Genome analyses of indicate that the locus is widespread in other ; including and species, and some and species. In contrast, the Csc pathway is limited mostly to , some species (in which loci are rendered non-functional by various mutations), and . The more efficient Scr pathway likely has greater potential than the Csc pathway for bioindustrial applications of and other using sucrose as a feedstock.