Zugl.: Paderborn, Universiẗat, Diss., 1995.

There is an increasing body of evidence that conjugated linoleic acid (c9t11 CLA) suppresses chemically induced tumor development in cell cultures and animal models. Ruminant-derived foods make a major contribution to total fat consumption and are the main source of c9t11 CLA in the human diet. In light of the potential benefits to long-term human health, there has been increased interest in enhancing the concentrations of potentially beneficial fatty acids (FA) in milk and meat. Factors affecting c9t11CLA production and secretion into milk fat have been extensively studied the last 10 years and a large pool of knowledge has accumulated. However, little information is currently available about the effects of feeding c9t11 CLA- stimulating diets on rumen microbial ecology, particularly, bacterial species believed to be involved in the biohydrogenation (BH) process. The main objective of this study was to evaluate the effect of lipid source on the DNA concentrations of selected ruminal bacteria. Four continuous culture fermenters were used in 4 x 4 Latin square design with four periods of 10 d each. Treatment diets were fed (45 g/d DM basis) in three equal portions during the day. The diets were 1) control diet (50% alfalfa pellets, 50% concentrate, CON), 2) CON plus saturated fat (rumofat; SAT), 3) CON plus soybean oil (SBO), and 4) CON plus fish oil (FO). Lipid supplements were added at 3% of diet DM. Lipid supplements had no effect on feed digestibility, total VFA and acetate concentrations or fermenter pH. Propionate concentration was higher with the FO diet in comparison with the other treatment diets. Butyrate concentration was similar between the SBO and FO diets and both were lower than the levels for the CON and SAT diets. The concentration of VA in effluents increased with SBO and FO diets and was highest with SBO diet. The concentrations of C18:0 in effluents were lowest for the FO diet compared with the other treatment diets. The concentrations of c9t11 CLA in effluents were similar between SBO and FO diets and both were higher than levels for the CON and SAT diets. Concentrations of DNA for total bacteria, A. lipolytica, C. proteoclasticum and S. dextrinosolvens were similar for all diets. The concentrations of B. fibrisolvens (69.1 pg/45ng total DNA) and R. albus (1.96 pg/45ng total DNA) were least with the FO diet but were similar among the other treatment diets (SAT-104.2; 5.4, SBO-121.2; 5.71, and CON-126.3; 5.17 pg/45ng total DNA). S. ruminantium DNA concentration was highest with the FO diet and was least with the SAT diet (177.5, 54.9, 75.5, and 691.1 pg/20ng total DNA for treatment diets 1 to 4, respectively). In conclusion, SBO had no effect on bacterial DNA concentrations tested in this study and the inhibitory effects of FO on BH may be due in part to its influence on B. fibrisolvens, R. albus and S. ruminantium.

No description available.

No description available.

No description available.

No description available.

Biliverdin IXα is a green bile pigment produced by enzymatic cleavage of a tetrapyrrole ring of heme by heme oxygenase. While biliverdin IXα is emerging as an effective cytoprotectant, the conventional method for producing biliverdin IXα by chemical conversion of animal bile is not suitable for large scale production. A novel scalable production method was pursued via bacterial fermentation. Recombinant Escherichia coli strains were obtained by sequence optimization and plasmid transformation of a cyanobacterial heme oxygenase gene. Further strain development was done by plasmid overexpression of a native E. coli flavodoxin gene as a possible electron donor for heterogeneous heme oxygenase. The resulting strains were grown in a fed-batch culture system optimized for biliverdin IXα production. Syringomycin E is a lipodepsinonapeptide produced by certain strains of Pseudomonas syringae pv. syringae by nonribosomal peptide synthesis. Though syringomycin E had been considered a phytotoxin in the past, recent research results indicate that syringomycin E is a natural fungicide that is not toxic to animals and plants. Syringomycin E is a potential fungicide especially for use in the organic agriculture sector. New strains of P. syringae pv. syringae were isolated through ultraviolet mutagenesis and screenings for enhanced capability to produce syringomycin E especially under agitated conditions. Fermentative production was conducted in a newly formulated medium and the product was purified through a large scale chromatography system using organic-compatible solvents. Purified syringomycin E was tested on cucumber seeds to examine its antifungal activity against a soil-borne pathogen Pythium ultimum. Syringomycin E was able to inhibit Pythium infection and protected seeds and seedlings without developing disease symptoms. This dissertation research showed scalable production of two natural products, biliverdin IXα and syringomycin E in bacterial platforms. Strain development by gene recombination and mutation was done to obtain bacterial strains capable of overproducing desired metabolites. The resulting strains were grown in fermenters to maximize the yields under agitated conditions. Monitoring growth parameters and medium modifications were critical to achieve large scale production.

Zugl.: Braunschweig, Techn. Univ., Diss., 2005

Techn. Universiẗat, Diss., 2004--Berlin.

Xanthan gum is one of the most common thickening agents used worldwide.The industrial manufacturing process of xanthan gum uses cheap, carbohydrate rich mediums for fermentation of the bacterium Xanthomonas campestris. The objective of this study was to compare different fermentation mediums based on grain powder for small scale fermentation of Xanthomonas campestris. Culture mediums containing wheat or cornstarch and the less allergen prone medium containing potato starch and oat flour were investigated. All four fermentation mediums of this study showed signs of thickening, indicating the presence of alive and growing Xanthamonas campetris. Based on the growth on MacConkey and NA-agar plates, all four fermentation products showed the presence of bacteria. The fermentation product from  a culture medium containing both potato starch and oat flour showed a higher concentration of bacteria compared to a culture medium containing wheat flour or cornstarch. The fermentation product in the presence of oat flour showed more than 100 times higher bacterial concentration in the fermentation product compared to wheat flour. Data suggests that potato starch and oat flour fermentation performed better than wheat flour and cornstarch and these less allergen prone mediums can be used as an alternative for fermentation of Xanthamonas campetris in the production of xanthan gum. / Xantangummi är ett av de vanligast förkommande förtjockningsmedlen som används i världen.I den industriella tillverkningsprocessen av xantangummi används billiga, kolhydratrika medier för fermentering av bakterien Xanthomonas campestris. Syftet med denna studie var att jämföra olika fermenteringsmedier innehållande vetemjöl, majsstärkelse, potatisstärkelse, och  havremjöl för småskalig fermentation av Xanthomonas campestris. Alla fyra fermentationsmedierna som användes i denna studie visade tecken på förtjockning, vilket indikerar närvaron av levande och växande Xanthamonas campetris. Baserat på tillväxten på MacConkey- och NA-agarplattor visade alla fyra fermenteringprodukterna närvaron av bakterium. Fermenteringsprodukten från odling i mediums innehållande både potatisstärkelse och havremjöl uppvisade en högre koncentration av bakterier jämfört med odlingsmedium innehållande vetemjöl eller majsstärkelse. Fermenteringprodukten i närvaro av havremjöl visade en mer än 100 gånger högre bakteriekoncentration jämfört med vetemjöl. Data tyder på att fermentering med potatisstärkelse och havremjöl ger bättre tillväxt än medium innehållande vetemjöl och majsstärkelse och att mindre allergenbenägna medium kan användas som alternativ för fermentering av Xanthamonas campetris vid produktion av xantangummi.