Bioethanol production by immobilized Sacharomyces cerevisiae var. ellipsoideuscells

Bioethanol can be produced by fermentation of sugars from various waste agricultural materials. Whichever system for bioethanol production is chosen, the attention must be paid to the overalleconomics and energy consumption. The aim of the present study was to investigate the immobilization of Sacharomyces cerevisiae var. ellipsoideus yeast cells for bioethanol production fromcorn meal hydrolyzates. For this purpose the biocompatible polymers such as polyvinil alcohol (PVA) and Ca-alginate were assessed. The parameters of ethanol fermentation, such as inoculumconcentration in different carriers and the choice of a convenient carrier for the efficient ethanol production were studied. The maximum ethanol concentration of 10.05% (w/w) was obtained in the fermentation of corn meal hydrolyzates by 5% (v/v) of inoculum concentration of the yeast immobilized in Ca-alginate using a method of electrostatic droplet generation. The repeated batch fermentation with the yeast immobilized in Ca-alginate indicated that alginate gels degraded after the second fermentation cycle. PVA carrier exhibited better mechanical properties and stability; however lower ethanol concentrations were achieved during the fermentation

Synthesis and characterization of self-assembled polyaniline nanotubes/silica nanocomposites

Self-assembled semiconducting, paramagnetic polyaniline nanotubes have been synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in aqueous medium in the presence of colloidal silica particles of an average diameter ∼12 nm, without added acid. The electrical conductivity of polyaniline nanotubes/silica nanocomposites is in the range (3.3-4.0) × 10-3 S cm-1. The presence of paramagnetic polaronic emeraldine salt form of polyaniline and phenazine units in nanocomposites was proved by FTIR, Raman, and EPR spectroscopies. The influence of the initial silica/aniline weight ratio on the morphology of polyaniline/silica nanocomposites was studied by scanning and transmission electron microscopies. Nano-composites synthesized by using the initial weight ratio silica/aniline ≤0.2 contain polyaniline nanotubes which have a typical outer diameter of 100-250 nm and an inner diameter of 10-80 nm, and nanorods with a diameter of 60-100 nm, accompanied with polyaniline/silica nanogranules, while the nanocomposite synthesized at weight ratio silica/aniline ∼2 contains polyaniline/silica nanogranules with an average diameter of 35-70 nm. The evolution of molecular and supramolecular structure of polyaniline in the presence of colloidal silica is discussed

Ethylene glycol and glycolic acid production by wild-type Escherichia coli

Ethylene glycol and glycolic acid are bulk chemicals with a broad range of applications. The ethylene glycol and glycolic acid biosynthesis pathways have been produced by microorganisms and used as a biological route for their production. Unlike the methods that use xylose or glucose as carbon sources, xylonic acid was used as a carbon source to produce ethylene glycol and glycolic acid in this study. Amounts of 4.2 g/L of ethylene glycol and 0.7 g/L of glycolic acid were produced by a wild‐type Escherichia coli W3110 within 10 H of cultivation with a substrate conversion ratio of 0.5 mol/mol. Furthermore, E. coli strains that produce solely ethylene glycol or glycolic acid were constructed. 10.3 g/L of glycolic acid was produced by E. coli ΔyqhD+aldA, and the achieved conversion ratio was 0.56 mol/mol. Similarly, the E. coli ΔaldA+yqhD produced 8.0 g/L of ethylene glycol with a conversion ratio of 0.71 mol/mol. Ethylene glycol and glycolic acid production by E. coli on xylonic acid as a carbon source provides new information on the biosynthesis pathway of these products and opens a novel way of biomass utilization