Identification Of One With Xylanase Activity Of Actinomycetes And Their Enzymatic Properties

Lignocellulose is the major product of photosynthesis and the most abundant renewable resources of organic form in the world. On average, lignocellulose consists of 45% cellulose, and 30% hemicelluloses which mainly appear as xylan in grasses and hardwoods. Complete degradation of these complex carbohydrates is required for either natural recycles of agricultural residues or bioconversions of chemical industries. Although hundreds of species of fungi and bacteria are able to produce cellulases and hemicellulases, relatively few can grow on lignocellulosic substrates because the entire set of enzymes is required for complete digestion of cellulose and xylan. These enzymes include extracellular cellulases and xylanases able to degrade crystalline cellulose and xylan backbones, and intracellular glucosidase, xylosidase, arabinosidase, acetyl xylan esterase and a-glucuronidase. From a bottle of purchased inoculums of straw mushroom we isolated Streptomyces sp. pp2, which grew on the media with straws as sole carbon source.Cultural characteristics and 16S rRNA gene sequence indicated that strain pp2 was a member of genus Streptomyces, while it was not identical with any reported species. Study showed that this strain also produced α-L-arabinosidase and P-D-Xylosidase. The activity of xylanase was 30.3 U/mg, a-L-arabinosidase was 1.81 U/mg, and β-D-Xylosidase was 0.04 U/mg. This strain inhibited the growth of Staphalococcus aureus, weakly restrains Bacillus subtilis and does not effect the growth of Escherichia coli, Candida albicans and Aspergillus niger. These results showed that strain pp2 was a potential new species of Streptomyces, and was competitively involved in biomass recycle in the nature.