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Over-express galactokinase (Galk1) in tissue plasminogen activator (tPA) producing CHO cells as a potential strategy to improve cell growth and product synthesis. tPA producing CHO cells were transfected with the galactokinase (Galk1) gene. CHO-Galk1 cells showed a 39% increase of the specific growth rate in galactose. Moreover, clones were able to use this hexose as their main carbon source to sustain growth contrary to their parental cell line. Metabolic Flux Analysis revealed that the CHO-Galk1 selected clone shows an active metabolism towards biomass and product synthesis, characterized by higher fluxes in the TCA cycle, which is consistent with increased cellular densities and final product concentration. This cellular engineering strategy, where modifications of key points of alternative carbon sources metabolism lead to an improved metabolism of these sugars, is a starting point towards the generation of new cell lines with reduced lactate synthesis and increased cell growth and productivity.

To determine Monod kinetics parameters (µmax, Ks, kd and YX/S) of the mesophilic H2 producer Clostridium termitidis grown on glucose and cellobiose by modeling in MATLAB.Maximum specific growth rates (µmax) were 0.22 and 0.24 h(-1) for glucose and cellobiose respectively; saturation constants (Ks) were 0.17 and 0.38 g l(-1) respectively and the biomass yields (YX/S) were 0.26 and 0.257 g dry wt g(-1) substrate. H2 yields of 1.99 and 1.11 mol H2 mol(-1) hexose equivalent were also determined for glucose and cellobiose respectively.The microbial kinetics of this model microorganism will enhance engineering biofuel production applications.

The white-rot basidiomycetes, Peniophora cinerea and Trametes suaveolens, can produce ethanol from hexoses. Although T. suaveolens produced negligible amounts of ethanol under aerobic conditions, P. cinerea produced ethanol under both aerobic and semi-aerobic conditions and assimilated glucose, mannose, fructose, galactose, sucrose, maltose and cellobiose with yields of ethanol of 0.41, 0.45, 0.44, 0.19, 0.41, 0.44 and 0.45 g per g hexose, respectively. The corresponding results for T. suaveolens were 0.39, 0.3, 0.13, 0.2, 0.37, 0.35 and 0.31 g ethanol/g hexose. Furthermore, P. cinerea exhibited simultaneous saccharification and fermentation of amorphous cellulose.

The use of lignocellulose as a source of sugars for bioproducts requires the development of biocatalysts that maximize product yields by fermenting mixtures of hexose and pentose sugars to completion. In this study, we implicate mgsA encoding methylglyoxal synthase (and methylglyoxal) in the modulation of sugar metabolism. Deletion of this gene (strain LY168) resulted in the co-metabolism of glucose and xylose, and accelerated the metabolism of a 5-sugar mixture (mannose, glucose, arabinose, xylose and galactose) to ethanol.

Escherichia coli W3110 derivatives, strains SZ63 and SZ85, were previously engineered to produce optically pure d(−) and l(+)-lactate from hexose and pentose sugars. To expand the substrate range, a cluster of sucrose genes (cscR′ cscA cscKB) was cloned and characterized from E. coli KO11. The resulting plasmid was functionally expressed in SZ63 but was unstable in SZ85. Over 500 mm d(−)-lactate was produced from sucrose and from molasses by SZ63(pLOI3501).

Porcine pancreatic lipase (PPL) catalysed acetylation of some pentose and hexose sugars was accomplished in organic solvents after their preadsorption on silica gel. The effects of solvent polarity, type and concentration of acyl donor were investigated.

Fructose utilization in laboratory-scale sucrose adjunct brewers wort fermentations, using the brewing strainS. cerevisiae IGC 4261, is predicted by a mathematical model based on the kinetic parameters of the membrane transport proteins which affect fructose uptake into the cell. These include biphasic fructose transport via a proton symport and the constitutive hexose facilitated diffusion system, plus the competitive inhibitory effect that glucose has on this latter component. Also the non-competitive inhibitory effects of a) maltose on fructose uptake via its proton symport and b) ethanol on biphasic fructose transport are incorporated within the model, as well as the inoculum size.

Candida shehatae ATCC 22984 fermented solutions of up to 260 g/L sugars derived by hydrolysis of whole barley. These solutions contained hexose: pentose 70∶30, the hexose being mainly glucose from the barley starch and the pentose being mainly xylose. At sugar concentrations of 180 g/L, fermentation was complete in 72 h, yielding 84 g/L ethanol, 0.47 g ethanol/g sugar. At 260 g/L, fermentation ceased when ethanol concentration reached 100 g/L, but resumed when the ethanol was removed by vacuum distillation, to yield finally 0.50 g ethanol/g sugar.

Saccharomyces cerevisiae and Clostridium acetobutylicum have been used to consecutively ferment molasses (5% solids) containing added pentose sugars (30 g/l). Butanol concentrations of 6.6 g/l and 3.7 g/l have been achieved from L-arabinose and D-xylose, respectively, in the presence of 22 g/l of ethanol.