M . T AN G NE Y, C . R OU S SE , M . YA ZD A NI AN A ND W. J . M IT C HE LL . 1998. Sucrose is the major carbon source in molasses, the traditional substrate employed in the industrial acetonebutanol-ethanol (ABE) fermentation by solventogenic clostridia. The utilization of sucrose by Clostridium beijerinckii NCIMB 8052 was investigated. Extracts prepared from cultures grown on sucrose (but not xylose or fructose) as the sole carbon source possessed sucrose phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS) activity. Extract fractionation and reconstitution experiments revealed that the entire sucrose Enzyme II complex resides within the membrane in this organism. Sucrose-6-phosphate hydrolase and fructokinase activities were also detected in sucrose grown cultures. The fructokinase activity, which is required specifically during growth on sucrose, was shown to be inducible under these conditions. A pathway for sucrose metabolism in this organism is proposed.

The antibacterial activity of various nanoparticles is gaining increasing interest due to its potential medical applications. In this work, we presented the synthesis of copper oxide nanoparticles prepared by chemical reduction from aqueous solutions of copper sulfate (CuSO 4) with sodium borohydride (NaBH 4) and hydrazine hydrate (N 2 H 4) as reductant and polyvinylpyrrolidone (PVP) as stabilizer. The X-ray diffraction spectra showed the formation of tenorite (CuO) and cuprite (Cu 2 O) nanoparticles when different ratios of CuSO 4 /NaBH 4 and CuSO 4 /N 2 H 4 were used. Photographs obtained by transmission electron microscopy (TEM) showed agglomerates of grains with a narrow size distribution (from 20 to 70 nm), whereas the radii of the individual particles were between 2 and 20 nm. Smaller nanoparticles and narrower particle size distributions were obtained when NaBH 4 was used. The results of antibacterial activity using the Kirby-Bauer method showed that nanoparticles obtained with NaBH 4 presented a reasonable bactericidal activity. Pseudomonas aureginosa and Staphylococcus aureus were more susceptible to the particle size than Escherichia coli. In addition, with small amounts of Cu 2 O in samples of CuO nanoparticles, the antibacterial susceptibility against Pseudomonas aureginosa was improved. Finally, nanoparticles of CuO incorporated into cotton by applying ultrasound waves remained impregnated after five washes.

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Copper–silver nanopowders (NPs) are synthesized using a combination of sonoelectrodeposition for the inner core and galvanic replacement reaction for the outer shell.