title: Over-expression of DAAO and catalase in Kluyveromyces marxianus through media optimization, permeabilization and GA stabilization techniques.
abstract: The selected thermotolerant, lactose-utilizing yeast strain Kluyveromyces marxianus NBIMCC 8362 possesses high specific d-amino acid oxidase activity (60Ug(-1)), which was increased nine-fold (545Ug(-1)) by design of the growth medium and conditions for d-amino oxidase induction. Applying an optimized simple and rapid procedure for chemical permeabilization of K. marxianus cells with the cationic detergent cetyltrimethylammonium bromide, the enzyme activities (d-amino acid oxidase and catalase) of the cells have been further increased for up to 43- and 58-fold, respectively. However, the enzyme activities of the permeabilized cells decreased rapidly due to the leakage of the enzymes. Treating the permeabilized cells with 0.1% glutaraldehyde at 4°C for 10min stabilized the enzyme in the cells and prevented their outflow. The process is stable for 10 cycles and the productivity measured was 16.6mmmoll(-1)h(-1). The d-alanine transformation efficiency of K. marxianus permeabilized and GA entrapted cells was 98%.
authors.affiliation: Department of General and Industrial Microbiology, Sofia University "St. Kliment Ohridski", Faculty of Biology, 8 "Dragan Tsankov" St., 1164 Sofia, Bulgaria.
authors.forename: Donka D
authors.initials: DD
authors.lastname: Kostova
authors.forename: Ventsislava Y
authors.initials: VY
authors.lastname: Petrova
authors.forename: Anna V
authors.initials: AV
authors.lastname: Kujumdzieva