ABC Transporters Required for Hexose Uptake by Clostridium phytofermentans

Abstract

Plant-fermenting Clostridia are anaerobic bacteria that recycle plant matter in soil and promote human health by fermenting dietary fiber in the intestine. Clostridia degrade plant biomass using extracellular enzymes and then uptake the liberated sugars for fermentation. The main sugars in plant biomass are hexoses, and here, we identify how hexoses are taken in to the cell by the model organism Clostridium phytofermentans . We show that this bacterium uptakes hexoses using a set of highly specific, nonredundant ABC transporters. Once in the cell, the hexoses are phosphorylated by intracellular hexokinases. This study provides insight into the functioning of abundant members of soil and intestinal microbiomes and identifies gene targets to engineer strains for industrial lignocellulosic fermentation.