Characterization of alpha-maltotetraohydrolase produced by Pseudomonas sp. MS300 isolated from the deepest site of the mariana trench.

We have isolated a Pseudomonas-like amylase producer, the strain MS300, which displayed a large halo on starch medium, from the deepest site of the Mariana Trench. The strain MS300 produced two major and two minor alpha-maltotetraohydrolases (G4-amylase). The two major G4-amylases share the same molecular weight of 55,000 but had different pI values, 5.0 and 4.7, respectively. The optimum temperature for activity of both major G4-amylases is 40 degrees C, and the optimum pH is 6.8 for one and 8.9 for the other. MS300 produced more amylase under high hydrostatic pressure than under atmospheric pressure. Strain MS300 may be active in the deep sea at a depth of 10,897 m.