초록
<P><B>Abstract</B></P> <P>In this study, chitin oligosaccharides have been successfully produced using chitinases from submerged fermentation of <I>Lecanicillium lecanii</I>. The highest Hex, Chit and Prot production was 0.14, 0.26 and 2.05U/mg of protein, respectively, which were attained varying pH from 5 to 8 after 96h. Culture conditions conducted at constant pH of 6 resulted in significantly lower enzyme production. The crude enzyme was partially purified by salting out with (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> followed by size exclusion chromatography to isolate the chitinase mixture for further chitin hydrolysis assays. In this regard, chitin substrates were pretreated with sonication and steam explosion <I>prior to</I> enzymatic reaction. Structural changes were observed with steam explosion with 11.28% reduction of the crystallinity index attained with the lowest chitin/water ratio (0.1g/mL). Pretreated chitins reached the highest production of reducing sugars (0.37mg/mL) and GlcNAc (0.59mg/mL) in 23.6% yield.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sonication and steam explosion are proposed for chitin pretreatment and their further use in enzymatic hydrolysis. </LI> <LI> Chitosans were also evaluated as substrates for chitinases. </LI> <LI> Steam explosion reduces crystallinity of chitin and enhanced enzymatic hydrolysis. </LI> </UL> </P>