Measurement of density and chemical concentration using a microfluidic chip.

A new microfluidic product for measuring fluid density, specific gravity and chemical concentration has been developed. At the core of this lab-on-a-chip sensor is a vacuum-sealed resonating silicon microtube. Measurements can be made with under a microliter of sample fluid, which is over 1000x less than is conventionally required. Since the product is MEMS-based the overall system size is a fraction of conventional density meters and it weighs much less than the traditional desk-top, temperature controlled, density meters. The syringe or pipette loaded system includes a dynamic temperature control system that operates between 0 degree C and 90 degree C with an accuracy of less than 0.01 degree C. Density measurement accuracies of 4 to 5 digits have been observed with aqueous solutions. Measurement examples and applications will be discussed.

Fermentations of pectin-rich biomass with recombinant bacteria to produce fuel ethanol.

Pectin-rich residues from sugar beet processing contain significant carbohydrates and insignificant amounts of lignin. Beet pulp was evaluated for conversion to ethanol using recombinant bacteria as biocatalysts. Hydrolysis of pectin-rich residues followed by ethanolic fermentations by yeasts has not been productive because galacturonic acid and arabinose are not fermentable to ethanol by these organisms. The three recombinant bacteria evaluated in this study, Escherichia coli strain KO11, Klebsiella oxytoca strain P2, and Erwinia chrysanthemi EC 16 pLOI 555, ferment carbohydrates in beet pulp with varying efficiencies. E. coli KO11 is able to convert pure galacturonic acid to ethanol with minimal acetate production. Using an enzyme loading of 10.5 filter paper units of cellulase, 120.4 polygalacturonase units of pectinase, and 6.4 g of cellobiase (per gram of dry wt sugar beet pulp), with substrate addition after 24 h of fermentation, 40 g of ethanol/L was produced. Other recombinants exhibited lower ethanol yields with increases in acetate and succinate production.