|Sugar transporters in efficient utilization of mixed sugar substrates: current knowledge and outlook.
Appl. Microbiol. Biotechnol. 85: 471-480. 2010. (Mini-Review)
T. Jojima, C.A. Omumasaba, M. Inui and H. Yukawa.
There is increasing interest in production of transportation fuels and commodity chemicals from lignocellulosic biomass, most desirably through biological fermentation. Considerable effort has been expended to develop efficient biocatalysts that convert sugars derived from lignocellulose directly to value-added products. Glucose, the building block of cellulose, is the most suitable fermentation substrate for industrial microorganisms such as Escherichia coli, Corynebacterium glutamicum, and Saccharomyces cerevisiae. Other sugars including xylose, arabinose, mannose, and galactose that
comprise hemicellulose are generally less efficient substrates in terms
of productivity and yield. Although metabolic engineering including introduction
of functional pentose-metabolizing pathways into pentose-incompetent microorganisms
has provided steady progress in pentose utilization, further improvements
in sugar mixture utilization by microorganisms is necessary. Among a variety
of issues on utilization of sugar mixtures by the microorganisms, recent
studies have started to reveal the importance of sugar transporters in
microbial fermentation performance. In this article, we review current
knowledge on diversity and functions of sugar transporters, especially
those associated with pentose uptake in microorganisms. Subsequently, we
review and discuss recent studies on engineering of sugar transport as
a driving force for efficient bioconversion of sugar mixtures derived from