AUTHOR=Stephens Craig , Martinez Mireille , Leonardi Virginia , Jaing Jasmine , Miller Anna 

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

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1409295

DOI=10.3389/fmicb.2024.1409295

ISSN=1664-302X

ABSTRACT=<p>Most <italic>Escherichia coli</italic> 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 <italic>E. coli</italic> to utilize sucrose for slow growth, and this pathway has been engineered in <italic>E. coli</italic> W strains to enhance use of sucrose as a feedstock for industrial applications. An alternative sucrose utilization pathway, Scr, was first identified in <italic>Klebsiella pneumoniae</italic> and has been reported in some <italic>E. coli</italic> and <italic>Salmonella enterica</italic> isolates. We show here that the Scr pathway is native to an important subset of <italic>E. coli</italic> phylogroup B2 lineages that lack the Csc pathway but grow rapidly on sucrose. Laboratory <italic>E. coli</italic> strains derived from MG1655 (phylogroup A, ST10) are unable to utilize sucrose and lack the <italic>scr</italic> and <italic>csc</italic> genes, but a recombinant plasmid-borne <italic>scr</italic> locus enables rapid growth on and fermentation of sucrose. Genome analyses of <italic>Enterobacteriaceae</italic> indicate that the <italic>scr</italic> locus is widespread in other <italic>Enterobacteriaceae</italic>; including <italic>Enterobacter</italic> and <italic>Klebsiella</italic> species, and some <italic>Citrobacter</italic> and <italic>Proteus</italic> species. In contrast, the Csc pathway is limited mostly to <italic>E. coli</italic>, some <italic>Shigella</italic> species (in which <italic>csc</italic> loci are rendered non-functional by various mutations), and <italic>Citrobacter freundii</italic>. The more efficient Scr pathway likely has greater potential than the Csc pathway for bioindustrial applications of <italic>E. coli</italic> and other <italic>Enterobacteriaceae</italic> using sucrose as a feedstock.</p>