Tuesday, May 1, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
The development of a cost-effective fermentation process for ethanol production from lignocellulosic hydrolysates will require a microorganism that is capable of high-efficiency and high-productivity conversion of both hexose and pentose sugars to ethanol. The bacterium Zymomonas mobilis was shown to be extremely attractive for the ethanol second generation production from glucose of the cellulosic fraction, due to its high capacity to absorb this sugar, resulting in high ethanol productivity values. However, the wild-type strains proved to be unable to metabolize the xylose arising from the hemicellulose fraction. In order to move forward on this issue and make more efficient the production of second generation ethanol, the incorporation of molecular biology techniques is recommended, in order to give the strains used in this study also able to ferment xylose into ethanol. Thus, the aim of this study was to evaluate the SSCF (simultaneous saccharification for and co-fermentation) process, in which the fermentation of both sugars occurs in one step. Thus, two operons under the control of the strong constitutive promoter of Pgap from Z. mobilis were constructed by chemical synthesis, using data from the genome of E. coli and Z. mobilis. The Z. mobilis plasmid pZMO1 of 1565 kb was chemically synthesized and cloned into a synthetic vector, that contain the E.Coli replication checkmark origin and tetracycline resistance. Metabolic adaptation was performed, followed by response surface experimental, evaluating the addition of glucose and xylose in the culture medium in different concentrations, noting that 40% of xylose was converted to ethanol.