Chitin Degradation by the Resting Cells of Chitinolytic Microorganism

The chitinolytic microorganisms, isolates 18 and 19, were selected from soil samples around a region of frozen shrimp factory in Chonburi province. These isolates had high potential for using chitin as a carbon source from the chitin broth, which was composed of 1.0% chitin, 1.0% NH4NO3 and 3.0% yeast extract. The cultures were grown at 200 rpm, 30∞C and initial pH of 6.8-7.0 for 7 days. It was found that the intact cells of isolates 18 and 19 had the chitinolytic activity of 19.51% and 20.31%, respectively. This study, the microorganisms were induced to transform the intact cells into the resting cells by freezethaw and ultrasonic method. The results showed that the resting cells which differentiated from the isolate 18 could be prepared by either 7 times of freeze-thaw or by 50% and 80% of sonicated amplitude for 35s and 15s, respectively. Additionally, the resting cells from these three methods had the chitinolytic activity about 31.01%, 25.06% and 25.01%, respectively. The preparation of the resting cells of isolate 19 was achieved by means of either 8 times of freeze-thaw or by 50% and 80% of sonicated amplitude for 70s and 35s, and yielded 24.78, 25.31 and 24.61% of chitinolytic activity, respectively. Key word: chitinolytic microorganism, chitin degradation, resting cell, ultrasonic, freeze-thaw