A Halotolerant Endo-1,4-ß-Xylanase from Aspergillus clavatus with Potential Application for Agroindustrial Residues Saccharification.

The use of non-potable water (such as seawater) is an attractive alternative for water intensive processes such as biomass pretreatment and saccharification steps in the production of biochemicals and biofuels. Identification and application of halotolerant enzymes compatible with high-salt conditions may reduce the energy needed for non-potable water treatment and decrease waste treatment costs. Here we present the biochemical properties of a halotolerant endo-1,4-ß-xylanase produced by Aspergillus clavatus in submerged fermentation, using paper sludge (XPS) and sugarcane bagasse (XSCB), and its potential application in the hydrolysis of agroindustrial residues. The peptide mass fingerprint and amino acid sequencing of the XPS and XSCB enzymes showed primary structure similarities with an endo-1,4-ß-xylanase from Aspergillus clavatus (XYNA_ASPCL). Both enzyme preparations presented good thermal stability at 50 °C and were stable over a wide range of pH and Vmax up to 2450 U/mg for XPS. XPS and XSCB were almost fully stable even after 24 h of incubation in the presence of up to 3 M NaCl, and their activity were not affected by 500 mM NaCl. Both enzyme preparations were capable of hydrolyzing paper sludge and sugarcane bagasse to release reducing sugars. These characteristics make this xylanase attractive to be used in the hydrolysis of biomass, particularly with brackish water or seawater.

Effect of drying methods on the powder and compaction properties of microcrystalline cellulose derived from Gossypium herbaceum

The effect of drying method, a process variable, on the powder and compaction properties of microcrystalline cellulose (MCC) obtained from the partial acid hydrolysis of bleached alpha (α) cellulose content of matured linters of Gossypium herbaceum (GH) was investigated. A portion of the wet MCC obtained was fluid bed dried at 60 ± 1 ºC, inlet air of 30 m3 min-1 for 3 h (coded MCC-GossF). The second portion was lyophilized at - 45 ± 2 ºC for 6 h (coded MCC-GossL). The physicochemical, scanning electron micrographs, X ray diffraction patterns and micromeritic properties of the derived MCCs were determined using standard methods. The cohesiveness and compactibility of the powders were investigated using Kawakita model while the deformation and compressibility pattern were determined using Heckel model. Avicel® PH 102 (AV-102) was used as comparing standard. Ash values of < 2%, pH (6.54 ± 0.23 to 6.58 ± 0.08), degree of polymerization, DP (231.50) was obtained. MCC-GossF had higher moisture content, swellability, better flow indices, and lesser porosity than MCC-GossL. Kawakita model demonstrated good consolidation and compactibility for both powders. Compacts of MCC-GossL were significantly (p < 0.05) harder than those of MCC-GossF. Heckel analysis demonstrated good compressibility and deformation pattern that was comparable with AV-102. Compacts of MCC-GossL had better mechanical and tablet compression properties than MCC-GossF

Temperature effect in the production of multiple xylanases by Aspergillus fumigatus.

This work has evaluated the temperature effect in the production of multiple xylanases by a locally isolated strain of Aspergillus fumigatus Fresenius. Three isoenzymes, identified as xylanases I, II, and III with apparent molecular weight of 45.7 KDa, 39.8 KDa and 18.2 KDa, respectively, were produced in cultures developed at 30 degrees C and at 42 degrees C. The pattern of distribution of xylanase activity among the three isoenzymes was greatly affected by the growth temperature: at 30 degrees C, the total xylanase activity was distributed homogeneously among the three enzymes, while at 42 degrees C, the total xylanase activity was mainly due to the fractions with the highest MW (I and II) and the xylanase III was a minor component.