No description available.

Potential thermophiles for ethanol production at elevated temperature were compared based on their kinetic performances. T. thermophilus HB27 demonstrated superior kinetics and its growth was not greatly affected when containing the recombinant plasmid pTEV231. Detailed kinetic studies demonstrated that it could utilize glucose and xylose in medium containing 0.5 % (w/v) yeast extract, and could produce low levels of L-lactate, acetate and ethanol. Kinetic evaluation of the newly isolated G. thermoglucosidasius M10EXG showed it could grow on fully defined media and coferment glucose and xylose. G. thermoglucosidasius M10EXG produced higher levels of products (acetate, and L-lactate) at about 2 g/l each, compared to T. thermophilus HB27 although ethanol levels were only 0.1-0.2 g/l in shake flask fermentations under partially aerobic conditions. Improved conditions for natural transformation of T. thermophilus HB27 were determined. Optimal conditions for electroporation of were: Milli-Q water washing of cells rather than with 10% (v/v) glycerol; an electrical field of 5 kV/cm; cell concentration of 1.4x1010 cells/ml; and a DNA concentration of 500 ng in 40 Fl (125 Fg/ml) which achieved a transformation efficiency of 3x103 transformants /Fg DNA. The chloramphenicol resistance (cat) and green fluorescence protein (gfp) genes from pCJS10 were cloned into an E. coli -- T. thermophilus shuttle vector (pMK18) as possible selection markers at elevated temperatures. Both genes were expressed in E. coli DH5H and it was demonstrated that gfp expression in E. coli DH5H decreased as temperature increased to 45oC. However following transformation of T. thermophilus HB27, no evidence of expression were found. The pet operon containing adhT (with its promoter) from G.thermoglucosidasius M10EXG and pdc from Z. mobilis Zm4, was cloned into pMK18 and low level expression in E. coli JM109 occurred with some increase in ethanol production. However the pet operon was not expressed in T. thermophilus with pMK18. For further gene expression studies, a new shuttle vector, pPOPTE (4-5 kb), based on the T. thermophilus plasmid pTEV231 (containing thermostable kanamycin resistance gene) was constructed. pPOPTE was capable of multiplying in both E. coli and T. thermophilus HB27 and demonstrated higher stability and transformation efficiency compared to pMK18.

No description available.

No description available.

No description available.

Digitized by Kansas Correctional Industries

Thesis (M.S.)--Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.

No description available.

No description available.

No description available.