A novel neutral and thermophilic endoxylanase from Streptomyces ipomoeae efficiently produced xylobiose from agricultural and forestry residues.

Endoxylanases capable of producing high ratios of xylobiose from agricultural and forestry residues in neutral and high temperature conditions are attractive for the prebiotic and alternative sweetener industries. In this study, a putative glycosyl hydrolase gene from Streptomyces ipomoeae was cloned and expressed in Escherichia coli. The recombinant enzyme, named as SipoEnXyn10A, hydrolyzed beechwood xylan in endo-action mode releasing xylobiose as its main end product. It was most active at pH 6.5 and 75-80 °C and showed remarkable stability at 65 °C. The xylobiose yield from 10 g corncob and moso bamboo reached 1.123 ±â€¯0.021 and 0.229 ±â€¯0.005 g, respectively, at pH 6.5 and 70 °C, whichwas higher than other reports using the same material. Moreover, high ratios of xylobiose in the xylose-based product of about 85% were obtained from corncob, moso bamboo sawdust, cassava stem and Chinese fir sawdust. These results demonstrated that SipoEnXyn10A has potential for industrial application.

Purification and Characterization of a Novel ß-Cypermethrin-Degrading Aminopeptidase from Pseudomonas aeruginosa GF31.

In this study, a novel ß-cypermethrin-degrading enzyme was isolated and purified by 32.8 fold from the extracellular cell-free filtrate of Pseudomonas aeruginosa GF31with the protein recovery of 26.6%. The molecular mass of the enzyme was determined to be 53 kDa. The optimum temperature for the activity was surprisingly 60 °C, and moreover, the purified enzyme showed a good pH stability, maintaining over 85% of its initial activity in the pH 5.0-9.0 range. Most of the common metal ions exhibited little influence on the activity except for Hg2+, Ag+, and Cu2+. After the complete gene sequence of the degrading enzyme was obtained by subcloning, sequence analyses as well as enzymatic properties demonstrated that the islolated enzyme should be an aminopeptidase. This is the first reported aminopeptidase for pyrethroid hydrolase, providing new potential enzyme resources for the degradation of this type of pesticide.

A novel non-hydrolytic protein from Pseudomonas oryzihabitans enhances the enzymatic hydrolysis of cellulose.

Several kinds of protein such as the expansin, expansin-like proteins and LPMOs (lytic polysaccharide monooxygenases) are known to exert enhancement effects on cellulase activity. In this study, a novel cellulase synergistic protein named POEP1 was purified from the culture filtrate of Pseudomonas oryzihabitans CGMCC 6169, and was homogeneous on SDS-PAGE with a molecular weight of 60kDa. Mass spectrometry analysis indicated that it was an unknown protein without sequence similarity to the expansin and expansin-like proteins. Evaluation of the enzymatic hydrolysis of filter paper revealed that POEP1 had no cellulase activity but displayed high synergistic activity of 364% at a cellulase concentration of 0.1FPU/g of filter paper. When a mixture containing 0.6FPU cellulase and 700µg POEP1 per g of cellulose was evaluated, the maximal sugar yield was achieved, which was 2.2-fold greater than that with the cellulase alone. POEP1 was found to have functional similarity to the expansin and expansin-like proteins, which could decrease both the hydrogen-bond intensity and crystallinity, and cause the filter paper disruption. This study provided evidence for the existence of novel bacterial proteins in nature serving the same function as expansin and expansin-like proteins.