Abstract:

In the present study, a psychrophilic pullulanase-producing strain, Pseudoalteromonas sp. NX-1, was isolated
from Antarctic marine sediment samples with optimum growth temperature of 20 ℃. The enzymatic properties of
pullulanase from strain NX-1 were investigated. The medium composition and culture conditions for pullulanase production
by NX-1 were optimized by single factor and orthogonal array experiments. The results showed the optimum catalytic pH of
the pullulanase was 7.0, and the half-life was 120 min at optimal catalytic conditions. The pullulanase activity of this isolate
was influenced in decreasing order by the following medium components sugar, peptone, CaCl2 and Na2HPO4. The optimal
culture conditions were 20 ℃ and an inoculum size of 1% using a medium consisting of 15 g/L sugar, 15 g/L peptone,
0.5 g/L CaCl2 and 6 g/L Na2HPO4. The yield of pullulanase was improved by 25.1% when compared to that obtained before
optimization that before.

Key words: psychrophilic pullulanase, Pseudoalteromonas, fermentation, orthogonal experiments