Isolation of Paenibacillus illinoisensis that produces cyclodextrin glucanotransferase resistant to organic solvents.

A bacterium that secreted cyclodextrin glucanotransferase (CGTase) in a medium overlaid with n-hexane was isolated and identified as Paenibacillus illinoisensis strain ST-12 K. The CGTase of the strain was purified from the culture supernatant. The molecular mass was 70 kDa. The enzyme was stable at pH 6 to 10 and active at pH 5.0 to 8.0. The optimum temperature at pH 7.0 was 65 degrees C in the presence of 5 mM CaCl2. The enzyme produced mainly beta-cyclodextrin. The total yield of alpha-, beta-, and gamma- cyclodextrins was increased 1.4-fold by the addition of ethanol. In particular, the yield of beta-cyclodextrins in the presence of 10% (vol/vol) ethanol was 1.6-fold that without ethanol. The CGTase was stable and active in the presence of large amounts of various organic solvents.