Ethanol production from corn cob hydrolysates by Escherichia coli KO11.

Corn cob hydrolysates, with xylose as the dominant sugar, were fermented to ethanol by recombinant Escherichia coli KO11. When inoculum was grown on LB medium containing glucose, fermentation of the hydrolysate was completed in 163 h and ethanol yield was 0.50 g ethanol/g sugar. When inoculum was grown on xylose, ethanol yield dropped, but fermentation was faster (113 h). Hydrolysate containing 72.0 g/l xylose and supplemented with 20.0 g/l rice bran was readily fermented, producing 36.0 g/l ethanol within 70 h. Maximum ethanol concentrations were not higher for fermentations using higher cellular concentration inocula. A simulation of an industrial process integrating pentose fermentation by E. coli and hexose fermentation by yeast was carried out. At the first step, E. coli fermented the hydrolysate containing 85.0 g/l xylose, producing 40.0 g/l ethanol in 94 h. Baker's yeast and sucrose (150.0 g/l) were then added to the spent fermentation broth. After 8 h of yeast fermentation, the ethanol concentration reached 104.0 g/l. This two-stage fermentation can render the bioconversion of lignocellulose to ethanol more attractive due to increased final alcohol concentration.

Effects of acetate on the growth and fermentation performance of Escherichia coli KO11.

Escherichia coli KO11, in which the genes pdc (pyruvate decarboxylase) and adh (alcohol dehydrogenase) encoding the ethanol pathway from Zymomonas mobilis were inserted into the chromosome, has been shown to metabolize all major sugars that are constituents of hemicellulosic hydrolysates to ethanol, in anaerobic conditions. However, the growth and fermentation performance of this recombinant bacteria may be affected by acetic acid, a potential inhibitor present in hemicellulose hydrolysates in a range of 2.0-15.0 g/L. It was observed that acetate affected the growth of E. coli KO11, prolonging the lag phase and inducing loss of biomass production and reduction of growth rate. At lower pH levels, the sensitivity to acetic acid was enhanced owing to the increased concentration of the protonated species. On the other hand, the recombinant bacteria showed a high tolerance to acetic acid regarding fermentative performance. In Luria broth medium with glucose or xylose as a single sugar source, it was observed that neither yield nor productivity was affected by the addition of acetate in a range of 2.0-12.0 g/L, suggesting some uncoupling of the growth vs ethanol production.

A Bordetella pertussis acellular vaccine candidate: antigenic characterization and antibody induction.

A single-step chromatography on Matrex-Gel Blue A has been employed to obtain soluble extracts containing some of the most important antigens of Bordetella pertussis, pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (69-kDa outer membrane protein), fimbriae (FIM2 and FIM3) and adenylate cyclase (AC). Two supernatants, P19 (48.8 mg PT, 6.8 mg FHA, 17.3 mg AC, 13 mg FIM2 and 4.9 mg FIM3 per liter) and P21 (0.1 mg PT, 0.07 mg FHA, 0.46 mg FIM2 and 0.94 mg FIM3 per liter), resulting from bacteria grown in Stainer-Scholte medium, were submitted to chromatography. Fractions with the antigens were obtained after stepwise elution with 60 mM sodium phosphate buffer, pH 6.0; 50 mM Tris-HCl, pH 7.4; 50 mM Tris-HCl, pH 7.4/0.75 M MgCl2; 50 mM Tris-HCl, pH 7.4/4 M MgCl2 and 4 M urea. Preparations from P19 (containing 4.05 micrograms PT, 8.14 micrograms FHA, 6.3 micrograms AC, 3.37 micrograms 69-kDa, 9.54 micrograms FIM2 and 2.23 micrograms FIM3) and from P21 (with 0.175 micrograms PT, 0.28 micrograms FHA, 0.002 micrograms 69-kDa, 0.005 micrograms FIM2 and 0.122 micrograms FIM3) were detoxified with glutaraldehyde and tested as an acellular pertussis vaccine. These products were non-toxic for mice and induced high levels of antibodies against purified pertussis antigens, as judged by ELISA.

A Bordetella pertussis acellular vaccine candidate: antigenic characterization and antibody induction

A single-step chromatography on Matrex-Gel Blue A has been employed to obtain soluble extracts containing some of the most important antigens of Bordetella pertussis, pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (69-kDa outer membrane protein), fimbriae (FIM2 and FIM3) and adenylate cyclase (AC). Two supernatants, P19 (48.8 mg PT, 6.8 mg FHA, 17.3 mg AC, 13 mg FIM2 and 4.9 mg FIM33 per liter) and P21 (0.1 mg PT, 0.07 mg FHA, 0.46 mg FIM2 and 0.94 mg FIM3 per liter), resulting from bacteria grown in Stainer-Scholte medium, were submitted to chromatography. Fractions with the antigens were obtained after stepwise elution with 60 mM sodium phosphate buffer, pH 6.0; 50 mM Tris-HC1, pH 7.4; 50 mM Tris-HC1, pH 7.4/0.75 M MgCl2; 50mM Tris-HCl, pH 7.4/4 M MgCl2 and 4 M urea. Preparations from P19 (containing 4.05 µg PT, 8.14 µg FHA, 6.3 µg AC, 3.37 µg 69-kDA, 9.54 µg FIM2 and 2.23 µg FIM3) and P21 (with 0.175 µg PT, 0.28 µg PT, 0.28 µg FHA, 0.002 µg69-kDa, 0.005 µg FIM2 and 0.122 µg FIM3) were detoxified with glutaraldehyde and tested as an acellular pertussis vaccine. These products were non-toxic for mice and induced high levels of antibodies against purified pertussis antigens, as judged by ELISA