Studies And Application Of Block Of Glucose Transportation Sysyem In Xanthomonas Campestris Pv. Campestris

Glucose, an intermediate of cellulose degradation, is the optimalcarbon source for almost all cellular organisms. Therefore, efficientconversation of cellulose into glucose would greatly benefit theproduction of bio-fuels with cellulose.It is not economic for this conversation through in vitro enzymaticcleavage with the isolated-glycosidase because large amounts ofthe commercial enzymes have to be invested. Alternative strategy is tocreate a novel engineered organism with capability of convertingcellulose to the desired products, which has a great challenge at present.Co-fermentation with two kinds of microbials, one is the strain forglucose production, the other one is for the fermentation of desiredproducts, seems to be an attractive approach. However, the efficiency ofthe total conversion is sometimes inflicted because of glucoseconsumption by the glucose production strain (donor strain). It will behelpful if the glucose uptake by the glucose production strain is inhibitedor blocked for such co-fermentation. For this purpose, X. campestris mutant strains with deletion of thegenes encoding glucose transporter were created through homologousrecombination. The mutation had little effect on growth, extra-cellularpolysaccharide accumulation, and extra-cellulase activities when culturedin NYG medium or minimal medium with glycerol as the sole carbonsource. However, more glucose was accumulated when the mutant strainswere cultured in minimal medium with carboxymethyl cellulose,suggesting blockage of glucose import is a good strategy limiting fuelwasting by the donor strain in co-fermentation.