Xylanase

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

Effect of Alkali Pretreatment of Rice Straw on Cellulase and Xylanase Production by Local Trichoderma harzianum SNRS3 under Solid State Fermentation

Abstract: Use of alkali-pretreated rice straw and untreated rice straw as substrates for enzyme production under solid-state cultivation was investigated. Cellulase produced from untreated rice straw showed higher activity of FPase, CMCase, β-glucosidase, and xylanase at 6.25 U/g substrate, 111.31 U/g substrate, 173.71 U/g substrate, and 433.75 U/g substrate respectively, as compared to 1.72 U/g substrate, 23.01 U/g substrate, 2.18 U/g substrate, and 45.46 U/g substrate for FPase, CMCase, β-glucosidase, and xylanase, respectively, when alkali-pretreated substrate was used. The results of the X-ray diffractogram analysis showed an increase in relative crystallinity of cellulose in alkali-pretreated rice straw (62.41%) compared to 50.81% in untreated rice straw. However, the crystalline structure of cellulose was partially disrupted after alkali pretreatment, resulting in a decrease in absolute crystallinity of cellulose. The higher the crystallinity of cellulose, the more cellulase production was induced. The structural changes of rice straw before and after alkali pretreatment were compared by using Scanning Electron Microscopy. Fungal mycelial growth was also observed for both untreated and alkali-pretreated substrates. The results of this study indicated that untreated rice straw is a better substrate for cellulase and xylanase production under solid-state fermentation with low environmental impact.

Applicability of thermo-alkali-stable and cellulase-free xylanase from a novel thermo-halo-alkaliphilic Bacillus halodurans in producing xylooligosaccharides

Abstract: An alkaliphilic, moderately thermophilic and halophilic bacterial isolate capable of producing a high titer of extracellular thermo-alkali-stable, cellulase-free endoxylanase was isolated from the paper mill effluents. It was identified as Bacillus halodurans. The purified xylanase was active from pH 7 to 12 and 30 to 100°C with optimal activity at pH 9.0 and 80°C. It had T1/2 values of 40 and 15 min at 70 and 80°C, respectively. Activity was stimulated by dithiothreitol but strongly inhibited by N-bromosuccinimide. Its action on birchwood xylan and agro-residues liberated xylooligosaccharides of 2–7 degree of polymerization, and thus, the mode of action is similar to endoxylanases of the family 10 glucoside hydrolases.

High-level xylanase production by alkaliphilic Bacillus pumilus ASH under solid-state fermentation

Abstract: Bacillus pumilus ASH produced a high level of an extracellular and thermostable xylanase enzyme when grown using solid-state fermentation (SSF). Among a few easily available lignocellulosics tested, wheat bran was found to be the best substrate (5,300 U/g of dry bacterial bran). Maximum xylanase production was achieved in 72 h (5,824 U/g). Higher xylanase activity was obtained when wheat bran was moistened with deionized water (6,378 U/g) at a substrate-to-moisture ratio of 1:2.5 (w/v). The optimum temperature for xylanase production was found to be 37°C. The inoculum level of 15% was found to be the most suitable for maximum xylanase production (7,087 U/g). Addition of peptone stimulated enzyme production followed by yeast extract and mustard oil cake, whereas glucose, xylose and malt extract greatly repressed the enzyme activity. Repression by glucose was concentration-dependent, repressing more than 60% of the maximum xylanase production at a concentration of 10% (w/v). Cultivation in large enamel trays yielded a xylanase titre that was slightly lower to that in flasks. The enzyme activity was slightly lower in SSF than in SmF but the ability of the organism to produce such a high level of xylanase at room temperature and with deionized water without addition of any mineral salts in SSF, could lead to substantial reduction in the overall cost of enzyme production. This is the first report on production of such a high level of xylanase under SSF conditions by bacteria.

The effect of sucrose supplements on particle-associated carboxymethylcellulase (EC 3.2.1.4) and xylanase (EC 3.2.1.8) activities in cattle given grass-silage-based diet.

Abstract: Carboxymethylcellulase (EC 3.2.1.4; CMCase) and xylanase (EC 3.2.1.8) activities were assayed in rumen fluid and from microbes closely associated either with rumen particulate material or with feed particles incubated in nylon bags in the rumen of cattle. The cattle were fitted with a permanent rumen cannula and a simple 'T'-piece duodenal cannula and were given four diets in a 4 x 4 Latin Square experiment. The basal diet (diet C) consisted of grass silage, barley and rapeseed meal (700, 240 and 60 g/kg total dry matter (DM)) given at the rate of 5.3 kg/d or supplemented with 1.0 kg sucrose/d given twice daily (diet S), twice daily with 0.25 kg sodium bicarbonate/d (diet B) or as a continuous intrarumen infusion (diet I). Giving sucrose supplements decreased CMCase and xylanase activities extracted from microbes associated with rumen particulate material or feed particles incubated in nylon bags as compared with diet C. Supplementation of the sucrose diet with sodium bicarbonate resulted in higher CMCase and xylanase activities than other sucrose diets (S and I). Particle-associated CMCase and xylanase activities were found to be very sensitive in detecting differences in the rumen environment and were related to changes in cell wall digestion. The activities were highly correlated with disappearance of DM and neutral-detergent fibre from nylon bags incubated in the rumen, rumen and total digestion of cell-wall carbohydrates and rumen pool size of cell-wall carbohydrates. It was concluded that the attachment of fibrinolytic enzymes is involved in the depression of fibre digestion. Particle-associated CMCase and xylanase activities were much higher when measured from rumen particulate material than from feed particles incubated in nylon bags.