The psychrotrophic Sanguibacter antarcticus KOPRI 21702(T), isolated from Antarctic seawater, produced a cold-adapted chitinolytic enzyme that is a new 55 kDa family 18 chitinase (Chi21702). Chi21702 exhibited high activities toward pNP-(GlcNAc)(2) and pNP-(GlcNAc)(3) with no activity for pNP-GlcNAc, indicating that it prefers chitin chains longer than dimers, just as endochitinases do. A mixture of GlcNAc and GlcNAc(2) Was produced as a main product by Chi21702 activity from chitin oligosaccharides and swollen chitin, while less GlcNAc(3) was produced. These results show that Chi21702 has an endochitinase activity, randomly hydrolyzing chitin at internal sites. Chi21702 displayed chitinase activity at 0-40 degrees C (optimal temperature of 37 degrees C), maintained its activity at pH 4-11 (optimal pH of 7.6). Interestingly, Chi21702 exhibited relative activities of 40% and 60% at 0 and 10 degrees C, respectively, in comparison to 100% at 37 degrees C, which is higher than those of the previously characterized, cold-adapted, chitinases from bacterial strains. (c) 2009 Elsevier Inc. All rights reserved.