Avtor/Urednik     Zorec, Maša
Naslov     Izolacija vampne bakterije z močno ksilanolitično aktivnostjo in opis njenega encimskega sistema za razgradnjo ksilana
Prevedeni naslov     Isolation of highly xylanolytic rumen bacterium and characterization of its enzymatic system for xylan degradation
Tip     monografija
Kraj izdaje     Ljubljana
Založnik     Medicinska fakulteta
Leto izdaje     2002
Obseg     str. 79
Jezik     slo
Abstrakt     Xylans are important part of plant structural polysaccharides and butyrivibrios are one of the most important xylanolytic bacterial groups in the rumen. From the rumen of a fistulated cow we isolated strain Mz5 in the medium with oat spelts xylan. The strain had the highest xylanolytic activity and following the morphological and biochemical characterization was classified as butyrivibrio. Xylanolytic activity of Mz5 was mainly cell-associated probably due to the production of extracellular polysaccharides (EPS) that hinder diffusion of the enzymes. Mz5 produces 11 electrophoretically multiple xylanases with molecular weights ranging from 27 to 146 kDa. Following the intensity of band decoloration on zymograms 6 major and 5 minor xylanases were identified. The highest cell-associated xylanolytic activity was achieved in the middle logarithmic phase (at 10 hours). 146 kDa xylanase was synthesized constitutively. Xylanase activity was strongly inducible with oat spelts xylan (130-times). 13-xylosidase and alpha-L-arabinofuranosidase activities were cell-associated. Butyrate, lactate and hydrogen gas were fermentation products on different substrates. Most of butyrate in regard to lactate was formed during the logarithmic phase irrespective of the substrate. Strain Mz5 could be used as a probiotic in animal feed because of its high native xylanolytic activities and production of butyrate that has beneficial effects on colonocytes. Competitive fitness is furthermore assured by the ability of fermentation of different substrates and fast adaptability due to short generation time.
Deskriptorji     XYLANS