Production and Some Properties of Salt-Tolerant β-Xylosidases from a Shoyu Koji Mold, Aspergillus oryzae in Solid and Liquid Cultures

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β-Xylosidase production from a shoyu (soy sause) koji mold, Aspergillus oryzae HL15, cultured in solid and liquid media was examined and some properties of the enzymes were studied. Three β-xylosidases (Xyl1, Xyl2 and Xyl3) were easily extracted with 0.5% NaCl from a solid medium and purified homogeneously on SDS-PAGE by chromatography. On the other hand, in a liquid medium, A.oryzae HL15 produced mainly cell-wall-bound β-xylosidases which could not be extracted with 0.5% NaCl or any detergent. Cell-wall-bound β-xylosidases, Xyl1-CB and Xyl2-CB, were liberated by digestion of mycelia with Yatalase and purified to a homogeneous state on SDS-PAGE by HPLC column chromatography. Four β-xylosidases (Xyl1, Xyl2, Xyl1-CB and Xyl2-CB) exhibited not only high activity at high NaCl concentrations, but also similar properties; on the other hand, Xyl3 differed in terms of thermostability and halophilic properties. The salt tolerance of β-xylosidases in A.oryzae suggests that these enzymes are highly active and involved in releasing xylose in shoyu moromi mash.
社団法人日本生物工学会の論文
1999-11-25