Highly thermostable purified xylanase from Rhizomucor miehei NRRL 3169

Abstract

A thermostable xylanase was purified and characterized from the thermophilic fungus Rhizomucor miehei (Cooney & R.Emers.) Schipper. The enzyme was purified 29.1-fold to homogeneity by ammonium sulfate precipitation, sephadex G-100 gel filtration and diethylaminoethyl cellulose anion exchange chromatography. The enzyme was highly active with a range of pH from 5.0 to 6.5. The optimum temperature of the purified enzyme was 75°C. The enzyme showed high thermal stability at 70 and 75°C, and the half-life of the xylanase at 90°C was 30 min. Km and Vmax values at 50°C of the purified enzyme were 0.055 mg/ml and 113.5 μmol min −1 mg −1 , respectively. The enzyme was activated by Ca 2+ , Cu 2+ , K + and Na + .On the other hand, Ag 2+ , Hg 2+ , Ba 2+ , and Zn 2+ inhibited the enzyme. The molecular weight of the xylanase was estimated to be 27 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The present study is among the first work to examine and describe a secreted highly thermostable xylanase from the Rhizomucor miehei fungus. This enzyme displays a number of biochemical properties that make it a potentially strong candidate for industrial and commercial application in pulp bleaching.

Purification and characterization of endoxylanase Xln-1 from Aspergillus niger B03

“…Th ese enzymes are responsible for the hydrolysis of the main chain. Enzymes such as α-L-arabinofuranosidase (EC 3.2.1.55), α-Dglucuronidase (EC 3.2.1.139), acetyl xylan esterase (EC 3.1.1.72), and ferulic or p-coumaric acid esterase (EC 3.2.1.73) are needed for debranching (2,3).…”

Production of thermostable xylanase by thermophilic fungal strains isolated from maize silage

“…Similar pH range was reported for the xylanase produced by Rh. miehei (Fawzi, 2010), while different results were reported for other fungi. For example, xylanase purified from Arthrobacter sp.…”

“…pusillus SOC-4A presented maximum activity between 65 and 75°C, with optimum value at 70°C (Figure 5). Fawzi (2010) reported an optimal temperature of 75°C for xylanase produced by Rh. miehei.…”

Investigation on lignocellulosic saccharification and characterization of haloalkaline solvent tolerant endo-1,4 β-d-xylanase from Halomonas meridiana APCMST-KS4

“…Among these xylanase from fungi and bacteria are extensively studied. Few examples for xylanase producing fungal species are Aspergillus niger DFR-5 (Pal and Khanum, 2011), Penicillium sclerotiorum (Knob and Carmona, 2010), Rhizomucor miehei NRRL 3169 (Fawzi, 2010), Talaromyces thermophilus (Maalej et al, 2009), Paecilomyces themophila (Li et al, 2006), Aspergillus niveus RS2 (Sudan and Bajaj, 2007) etc.…”