Anna Wojtasz-Pająk1,
Ilona Kołodziejska2, Aleksandra
DĘBOGÓRSKA2 and MAŁGORZATa Malesa-CIEĆWIERZ1
1 Sea Fisheries Institute,
Kołłątaja 1, 81-332 Gdynia, Poland
2 Technical
University of Gdańsk, Gabriela Narutowicza 11/12, 80-952 Gdańsk, Poland
Key words: chitin, chitin deacetylase, enzymatic, physical and chemical modifications.
Abstract.
Crystalline chitin was modified by physical, chemical and enzymatic
methods in order to increase its susceptibility to enzymatic deacetylation.
Of the physical factors, the following were used: microwave and ionizing
radiation, ultrasonics and autoclaving. By alkaline treatment (50% NaOH
solution, at 60-85C, for 15-180 minutes) a range of polymers differing
in the deacetylation degree were obtained. For enzymatic modifications
the endochitinase EC 3.2.1.14 from Streptomyces griseus was used. The examined
physical factors did not change significantly the susceptibility of chitin
to deacetylation. Treatment of crystalline and colloidal chitin with chitinase
decreased the amount of acetic acid released from these materials by the
deacetylase extract. All products of alkaline treatment of chitin were
susceptible to the action of deacetylase. By treating chitin with a 50%
NaOH solution at 60C for 90 and 180 minutes, chitosans were produced of
a deacetylation degree of 68 and 76, respectively, almost completely soluble
in diluted acetic acid and in acid buffer solutions. These polymers can
be used for biotechnological production of chitosan of required content
of acetyl groups.