Xylanase

About: Xylanase is a research topic. Over the lifetime, 7099 publications have been published within this topic receiving 163793 citations.

Relationship Between Cellulolytic Activity and Adhesion to Cellulose in Ruminococcus Albus

Abstract: SUMMARY: Bacterial adhesion to cellulose was measured for 13 cellulolytic and 10 non-cellulolytic, xylan-utilizing strains of the ruminal bacterium Ruminococcus albus. Radiolabelled bacteria adhering to Whatman CF11 cellulose powder were determined. Adhesion of the cellulolytic strains ranged from 0 to 49% of the added bacteria. Of the non-cellulolytic strains, 9 showed < 1% adhesion, while one strain gave 5% adhesion. For the cellulolytic strains filter paper solubilization ranged from 24 to 100%, while solubilization of CF11 cellulose varied from 0 to 20%. Both cellulolytic and non-cellulolytic strains produced carboxymethylcellulase (CMCase) activity. SDS-PAGE of cell extracts followed by incubation with a gel overlay containing CMC or xylan produced a zymogram of hydrolytic enzyme activity. The cellulolytic strains showed a number of bands of CMCase and xylanase activity. Non-cellulolytic strains possessed fewer bands of activity towards both CMC and xylan. Certain of the enzymes appeared to possess both CMCase and xylanase activity. Bacterial cell surface hydrophobicity was also measured, but no correlation was found between hydrophobicity and adhesion to cellulose.

Thermolabile xylanase of the Antarctic yeast Cryptococcus adeliae: production and properties.

Abstract: Xylanase production by the Antarctic psychrophilic yeast Cryptococcus adeliae was increased 4.3 fold by optimizing the culture medium composition using statistical designs. The optimized medium containing 24.2 g l−1 xylan and 10.2 g l−1 yeast extract and having an initial pH of 7.5 yielded xylanase activity at 400 nkat (nanokatal) ml−1 after 168-h shake culture at 4°C. In addition, very little endoglucanase, β-mannanase, β-xylosidase, β-glucosidase, α-l-arabinofuranosidase, and no filter paper cellulase activities were detected. Among 12 carbon sources tested, maximum xylanase activity was induced by xylan, followed by lignocelluloses such as steamed wheat straw and alkali-treated bagasse. The level of enzyme activity produced on other carbon sources appeared to be constitutive. Among the complex organic nitrogen sources tested, the xylanase activity was most enhanced by yeast extract, followed by soymeal, Pharmamedia (cotton seed protein), and Alburex (potato protein). A batch culture at 10°C in a 5-l fermenter (3.5-1 working volume) using the optimized medium gave 385 nkat at 111 h of cultivation. The crude xylanase showed optimal activity at pH 5.0–5.5 and good stability at pH 4–9 (21 h at 4°C). Although the enzyme was maximally active at 45°–50°C, it appeared very thermolabile, showing a half-life of 78 min at 35°C. At 40°–50°C, it lost 71%–95% activity within 5 min. This is the first report on the production as well as on the properties of thermolabile xylanase produced by an Antarctic yeast.

Effect of Exogenous Xylanase Supplementation on the Performance, Net Energy and Gut Microflora of Broiler Chickens Fed Wheat-based Diets

Abstract: An experiment was carried out to assess the effects of xylanase supplementation on the performance, net energy and gut microflora of broilers fed a wheat-based diet. Day-old male broiler chicks were allocated to two dietary treatments. Each treatment was composed of six replicate cages of seven broilers per cage. The diets were wheat-based and offered as mash. The treatments included i) basal diet deficient in metabolizable energy; and ii) basal diet supplemented with a commercial xylanase added at 4,000 U/kg feed. Bird performance, nutrient utilization and gut microbial populations were measured. Heat production and net energy were determined using an auto-control, open circuit respiration calorimetry apparatus. Results showed that exogenous xylanase supplementation improved feed conversion efficiency (p, and consumption of . The respiratory quotient (RQ) was also increased (p0.05). The ileal digestibility of hemicellulose was significantly improved by xylanase addition (p